tsserverProjectSystem.ts

namespace ts.projectSystem {
    import TI = server.typingsInstaller;
    import protocol = server.protocol;
    import CommandNames = server.CommandNames;

    export import TestServerHost = TestFSWithWatch.TestServerHost;
    export type File = TestFSWithWatch.File;
    export type SymLink = TestFSWithWatch.SymLink;
    export type Folder = TestFSWithWatch.Folder;
    export import createServerHost = TestFSWithWatch.createServerHost;
    export import checkArray = TestFSWithWatch.checkArray;
    export import libFile = TestFSWithWatch.libFile;
    export import checkWatchedFiles = TestFSWithWatch.checkWatchedFiles;
    export import checkWatchedFilesDetailed = TestFSWithWatch.checkWatchedFilesDetailed;
    export import checkWatchedDirectories = TestFSWithWatch.checkWatchedDirectories;
    export import checkWatchedDirectoriesDetailed = TestFSWithWatch.checkWatchedDirectoriesDetailed;
    import safeList = TestFSWithWatch.safeList;
    import Tsc_WatchDirectory = TestFSWithWatch.Tsc_WatchDirectory;

    export const customTypesMap = {
        path: <Path>"/typesMap.json",
        content: `{
            "typesMap": {
                "jquery": {
                    "match": "jquery(-(\\\\.?\\\\d+)+)?(\\\\.intellisense)?(\\\\.min)?\\\\.js$",
                    "types": ["jquery"]
                },
                "quack": {
                    "match": "/duckquack-(\\\\d+)\\\\.min\\\\.js",
                    "types": ["duck-types"]
                }
            },
            "simpleMap": {
                "Bacon": "baconjs",
                "bliss": "blissfuljs",
                "commander": "commander",
                "cordova": "cordova",
                "react": "react",
                "lodash": "lodash"
            }
        }`
    };

    export interface PostExecAction {
        readonly success: boolean;
        readonly callback: TI.RequestCompletedAction;
    }

    export const nullLogger: server.Logger = {
        close: noop,
        hasLevel: () => false,
        loggingEnabled: () => false,
        perftrc: noop,
        info: noop,
        msg: noop,
        startGroup: noop,
        endGroup: noop,
        getLogFileName: () => undefined,
    };

    function createHasErrorMessageLogger() {
        let hasErrorMsg = false;
        const { close, hasLevel, loggingEnabled, startGroup, endGroup, info, getLogFileName, perftrc } = nullLogger;
        const logger: server.Logger = {
            close, hasLevel, loggingEnabled, startGroup, endGroup, info, getLogFileName, perftrc,
            msg: () => {
                hasErrorMsg = true;
            }
        };
        return { logger, hasErrorMsg: () => hasErrorMsg };
    }

    export class TestTypingsInstaller extends TI.TypingsInstaller implements server.ITypingsInstaller {
        protected projectService: server.ProjectService;
        constructor(
            readonly globalTypingsCacheLocation: string,
            throttleLimit: number,
            installTypingHost: server.ServerHost,
            readonly typesRegistry = createMap<MapLike<string>>(),
            log?: TI.Log) {
            super(installTypingHost, globalTypingsCacheLocation, safeList.path, customTypesMap.path, throttleLimit, log);
        }

        protected postExecActions: PostExecAction[] = [];

        isKnownTypesPackageName = notImplemented;
        installPackage = notImplemented;

        executePendingCommands() {
            const actionsToRun = this.postExecActions;
            this.postExecActions = [];
            for (const action of actionsToRun) {
                action.callback(action.success);
            }
        }

        checkPendingCommands(expectedCount: number) {
            assert.equal(this.postExecActions.length, expectedCount, `Expected ${expectedCount} post install actions`);
        }

        onProjectClosed = noop;

        attach(projectService: server.ProjectService) {
            this.projectService = projectService;
        }

        getInstallTypingHost() {
            return this.installTypingHost;
        }

        installWorker(_requestId: number, _args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
            this.addPostExecAction("success", cb);
        }

        sendResponse(response: server.SetTypings | server.InvalidateCachedTypings) {
            this.projectService.updateTypingsForProject(response);
        }

        enqueueInstallTypingsRequest(project: server.Project, typeAcquisition: TypeAcquisition, unresolvedImports: server.SortedReadonlyArray<string>) {
            const request = server.createInstallTypingsRequest(project, typeAcquisition, unresolvedImports, this.globalTypingsCacheLocation);
            this.install(request);
        }

        addPostExecAction(stdout: string | string[], cb: TI.RequestCompletedAction) {
            const out = isString(stdout) ? stdout : createNpmPackageJsonString(stdout);
            const action: PostExecAction = {
                success: !!out,
                callback: cb
            };
            this.postExecActions.push(action);
        }
    }

    function createNpmPackageJsonString(installedTypings: string[]): string {
        const dependencies: MapLike<any> = {};
        for (const typing of installedTypings) {
            dependencies[typing] = "1.0.0";
        }
        return JSON.stringify({ dependencies });
    }

    export function createTypesRegistry(...list: string[]): Map<MapLike<string>> {
        const versionMap = {
            "latest": "1.3.0",
            "ts2.0": "1.0.0",
            "ts2.1": "1.0.0",
            "ts2.2": "1.2.0",
            "ts2.3": "1.3.0",
            "ts2.4": "1.3.0",
            "ts2.5": "1.3.0",
            "ts2.6": "1.3.0",
            "ts2.7": "1.3.0"
        };
        const map = createMap<MapLike<string>>();
        for (const l of list) {
            map.set(l, versionMap);
        }
        return map;
    }

    function createHostModuleResolutionTrace(host: TestServerHost & ModuleResolutionHost) {
        const resolutionTrace: string[] = [];
        host.trace = resolutionTrace.push.bind(resolutionTrace);
        return resolutionTrace;
    }

    export function toExternalFile(fileName: string): protocol.ExternalFile {
        return { fileName };
    }

    export function toExternalFiles(fileNames: string[]) {
        return map(fileNames, toExternalFile);
    }

    export function fileStats(nonZeroStats: Partial<server.FileStats>): server.FileStats {
        return { ts: 0, tsx: 0, dts: 0, js: 0, jsx: 0, deferred: 0, ...nonZeroStats };
    }

    export class TestServerEventManager {
        private events: server.ProjectServiceEvent[] = [];
        readonly session: TestSession;
        readonly service: server.ProjectService;
        readonly host: TestServerHost;
        constructor(files: File[], suppressDiagnosticEvents?: boolean) {
            this.host = createServerHost(files);
            this.session = createSession(this.host, {
                canUseEvents: true,
                eventHandler: event => this.events.push(event),
                suppressDiagnosticEvents,
            });
            this.service = this.session.getProjectService();
        }

        getEvents(): ReadonlyArray<server.ProjectServiceEvent> {
            const events = this.events;
            this.events = [];
            return events;
        }

        getEvent<T extends server.ProjectServiceEvent>(eventName: T["eventName"]): T["data"] {
            let eventData: T["data"] | undefined;
            filterMutate(this.events, e => {
                if (e.eventName === eventName) {
                    if (eventData !== undefined) {
                        assert(false, "more than one event found");
                    }
                    eventData = e.data;
                    return false;
                }
                return true;
            });
            return Debug.assertDefined(eventData);
        }

        hasZeroEvent<T extends server.ProjectServiceEvent>(eventName: T["eventName"]) {
            this.events.forEach(event => assert.notEqual(event.eventName, eventName));
        }

        checkSingleConfigFileDiagEvent(configFileName: string, triggerFile: string) {
            const eventData = this.getEvent<server.ConfigFileDiagEvent>(server.ConfigFileDiagEvent);
            assert.equal(eventData.configFileName, configFileName);
            assert.equal(eventData.triggerFile, triggerFile);
        }

        assertProjectInfoTelemetryEvent(partial: Partial<server.ProjectInfoTelemetryEventData>, configFile = "/tsconfig.json"): void {
            assert.deepEqual<server.ProjectInfoTelemetryEventData>(this.getEvent<server.ProjectInfoTelemetryEvent>(server.ProjectInfoTelemetryEvent), {
                projectId: sys.createSHA256Hash!(configFile),
                fileStats: fileStats({ ts: 1 }),
                compilerOptions: {},
                extends: false,
                files: false,
                include: false,
                exclude: false,
                compileOnSave: false,
                typeAcquisition: {
                    enable: false,
                    exclude: false,
                    include: false,
                },
                configFileName: "tsconfig.json",
                projectType: "configured",
                languageServiceEnabled: true,
                version,
                ...partial,
            });
        }

        assertOpenFileTelemetryEvent(info: server.OpenFileInfo): void {
            assert.deepEqual<server.OpenFileInfoTelemetryEventData>(this.getEvent<server.OpenFileInfoTelemetryEvent>(server.OpenFileInfoTelemetryEvent), { info });
        }
        assertNoOpenFilesTelemetryEvent(): void {
            this.hasZeroEvent<server.OpenFileInfoTelemetryEvent>(server.OpenFileInfoTelemetryEvent);
        }
    }

    class TestSession extends server.Session {
        private seq = 0;
        public events: protocol.Event[] = [];
        public host: TestServerHost;

        getProjectService() {
            return this.projectService;
        }

        public getSeq() {
            return this.seq;
        }

        public getNextSeq() {
            return this.seq + 1;
        }

        public executeCommandSeq<T extends server.protocol.Request>(request: Partial<T>) {
            this.seq++;
            request.seq = this.seq;
            request.type = "request";
            return this.executeCommand(<T>request);
        }

        public event<T extends object>(body: T, eventName: string) {
            this.events.push(server.toEvent(eventName, body));
            super.event(body, eventName);
        }

        public clearMessages() {
            clear(this.events);
            this.host.clearOutput();
        }
    }

    export function createSession(host: server.ServerHost, opts: Partial<server.SessionOptions> = {}) {
        if (opts.typingsInstaller === undefined) {
            opts.typingsInstaller = new TestTypingsInstaller("/a/data/", /*throttleLimit*/ 5, host);
        }

        if (opts.eventHandler !== undefined) {
            opts.canUseEvents = true;
        }

        const sessionOptions: server.SessionOptions = {
            host,
            cancellationToken: server.nullCancellationToken,
            useSingleInferredProject: false,
            useInferredProjectPerProjectRoot: false,
            typingsInstaller: undefined!, // TODO: GH#18217
            byteLength: Utils.byteLength,
            hrtime: process.hrtime,
            logger: opts.logger || nullLogger,
            canUseEvents: false
        };

        return new TestSession({ ...sessionOptions, ...opts });
    }

    interface CreateProjectServiceParameters {
        cancellationToken?: HostCancellationToken;
        logger?: server.Logger;
        useSingleInferredProject?: boolean;
        typingsInstaller?: server.ITypingsInstaller;
        eventHandler?: server.ProjectServiceEventHandler;
    }

    export class TestProjectService extends server.ProjectService {
        constructor(host: server.ServerHost, logger: server.Logger, cancellationToken: HostCancellationToken, useSingleInferredProject: boolean,
            typingsInstaller: server.ITypingsInstaller, eventHandler: server.ProjectServiceEventHandler, opts: Partial<server.ProjectServiceOptions> = {}) {
            super({
                host,
                logger,
                cancellationToken,
                useSingleInferredProject,
                useInferredProjectPerProjectRoot: false,
                typingsInstaller,
                typesMapLocation: customTypesMap.path,
                eventHandler,
                ...opts
            });
        }

        checkNumberOfProjects(count: { inferredProjects?: number, configuredProjects?: number, externalProjects?: number }) {
            checkNumberOfProjects(this, count);
        }
    }
    export function createProjectService(host: server.ServerHost, parameters: CreateProjectServiceParameters = {}, options?: Partial<server.ProjectServiceOptions>) {
        const cancellationToken = parameters.cancellationToken || server.nullCancellationToken;
        const logger = parameters.logger || nullLogger;
        const useSingleInferredProject = parameters.useSingleInferredProject !== undefined ? parameters.useSingleInferredProject : false;
        return new TestProjectService(host, logger, cancellationToken, useSingleInferredProject, parameters.typingsInstaller!, parameters.eventHandler!, options); // TODO: GH#18217
    }

    export function checkNumberOfConfiguredProjects(projectService: server.ProjectService, expected: number) {
        assert.equal(projectService.configuredProjects.size, expected, `expected ${expected} configured project(s)`);
    }

    function checkNumberOfExternalProjects(projectService: server.ProjectService, expected: number) {
        assert.equal(projectService.externalProjects.length, expected, `expected ${expected} external project(s)`);
    }

    function checkNumberOfInferredProjects(projectService: server.ProjectService, expected: number) {
        assert.equal(projectService.inferredProjects.length, expected, `expected ${expected} inferred project(s)`);
    }

    export function checkNumberOfProjects(projectService: server.ProjectService, count: { inferredProjects?: number, configuredProjects?: number, externalProjects?: number }) {
        checkNumberOfConfiguredProjects(projectService, count.configuredProjects || 0);
        checkNumberOfExternalProjects(projectService, count.externalProjects || 0);
        checkNumberOfInferredProjects(projectService, count.inferredProjects || 0);
    }

    export function configuredProjectAt(projectService: server.ProjectService, index: number) {
        const values = projectService.configuredProjects.values();
        while (index > 0) {
            values.next();
            index--;
        }
        return values.next().value;
    }

    export function checkProjectActualFiles(project: server.Project, expectedFiles: string[]) {
        checkArray(`${server.ProjectKind[project.projectKind]} project, actual files`, project.getFileNames(), expectedFiles);
    }

    function checkProjectRootFiles(project: server.Project, expectedFiles: string[]) {
        checkArray(`${server.ProjectKind[project.projectKind]} project, rootFileNames`, project.getRootFiles(), expectedFiles);
    }

    function mapCombinedPathsInAncestor(dir: string, path2: string, mapAncestor: (ancestor: string) => boolean) {
        dir = normalizePath(dir);
        const result: string[] = [];
        forEachAncestorDirectory(dir, ancestor => {
            if (mapAncestor(ancestor)) {
                result.push(combinePaths(ancestor, path2));
            }
        });
        return result;
    }

    function getRootsToWatchWithAncestorDirectory(dir: string, path2: string) {
        return mapCombinedPathsInAncestor(dir, path2, ancestor => ancestor.split(directorySeparator).length > 4);
    }

    const nodeModules = "node_modules";
    function getNodeModuleDirectories(dir: string) {
        return getRootsToWatchWithAncestorDirectory(dir, nodeModules);
    }

    export const nodeModulesAtTypes = "node_modules/@types";
    export function getTypeRootsFromLocation(currentDirectory: string) {
        return getRootsToWatchWithAncestorDirectory(currentDirectory, nodeModulesAtTypes);
    }

    function getNumberOfWatchesInvokedForRecursiveWatches(recursiveWatchedDirs: string[], file: string) {
        return countWhere(recursiveWatchedDirs, dir => file.length > dir.length && startsWith(file, dir) && file[dir.length] === directorySeparator);
    }

    function checkOpenFiles(projectService: server.ProjectService, expectedFiles: File[]) {
        checkArray("Open files", arrayFrom(projectService.openFiles.keys(), path => projectService.getScriptInfoForPath(path as Path)!.fileName), expectedFiles.map(file => file.path));
    }

    function protocolLocationFromSubstring(str: string, substring: string): protocol.Location {
        const start = str.indexOf(substring);
        Debug.assert(start !== -1);
        return protocolToLocation(str)(start);
    }
    function protocolToLocation(text: string): (pos: number) => protocol.Location {
        const lineStarts = computeLineStarts(text);
        return pos => {
            const x = computeLineAndCharacterOfPosition(lineStarts, pos);
            return { line: x.line + 1, offset: x.character + 1 };
        };
    }
    function protocolTextSpanFromSubstring(str: string, substring: string, options?: SpanFromSubstringOptions): protocol.TextSpan {
        const span = textSpanFromSubstring(str, substring, options);
        const toLocation = protocolToLocation(str);
        return { start: toLocation(span.start), end: toLocation(textSpanEnd(span)) };
    }
    function textSpanFromSubstring(str: string, substring: string, options?: SpanFromSubstringOptions): TextSpan {
        const start = nthIndexOf(str, substring, options ? options.index : 0);
        Debug.assert(start !== -1);
        return createTextSpan(start, substring.length);
    }
    function protocolFileLocationFromSubstring(file: File, substring: string): protocol.FileLocationRequestArgs {
        return { file: file.path, ...protocolLocationFromSubstring(file.content, substring) };
    }
    function protocolFileSpanFromSubstring(file: File, substring: string, options?: SpanFromSubstringOptions) {
        return { file: file.path, ...protocolTextSpanFromSubstring(file.content, substring, options) };
    }
    function documentSpanFromSubstring(file: File, substring: string, options?: SpanFromSubstringOptions): DocumentSpan {
        return { fileName: file.path, textSpan: textSpanFromSubstring(file.content, substring, options) };
    }
    interface SpanFromSubstringOptions {
        readonly index: number;
    }

    function nthIndexOf(str: string, substr: string, n: number): number {
        let index = -1;
        for (; n >= 0; n--) {
            index = str.indexOf(substr, index + 1);
            if (index === -1) return -1;
        }
        return index;
    }

    /**
     * Test server cancellation token used to mock host token cancellation requests.
     * The cancelAfterRequest constructor param specifies how many isCancellationRequested() calls
     * should be made before canceling the token. The id of the request to cancel should be set with
     * setRequestToCancel();
     */
    export class TestServerCancellationToken implements server.ServerCancellationToken {
        private currentId: number | undefined = -1;
        private requestToCancel = -1;
        private isCancellationRequestedCount = 0;

        constructor(private cancelAfterRequest = 0) {
        }

        setRequest(requestId: number) {
            this.currentId = requestId;
        }

        setRequestToCancel(requestId: number) {
            this.resetToken();
            this.requestToCancel = requestId;
        }

        resetRequest(requestId: number) {
            assert.equal(requestId, this.currentId, "unexpected request id in cancellation");
            this.currentId = undefined;
        }

        isCancellationRequested() {
            this.isCancellationRequestedCount++;
            // If the request id is the request to cancel and isCancellationRequestedCount
            // has been met then cancel the request. Ex: cancel the request if it is a
            // nav bar request & isCancellationRequested() has already been called three times.
            return this.requestToCancel === this.currentId && this.isCancellationRequestedCount >= this.cancelAfterRequest;
        }

        resetToken() {
            this.currentId = -1;
            this.isCancellationRequestedCount = 0;
            this.requestToCancel = -1;
        }
    }

    export function makeSessionRequest<T>(command: string, args: T): protocol.Request {
        return {
            seq: 0,
            type: "request",
            command,
            arguments: args
        };
    }

    export function executeSessionRequest<TRequest extends protocol.Request, TResponse extends protocol.Response>(session: server.Session, command: TRequest["command"], args: TRequest["arguments"]): TResponse["body"] {
        return session.executeCommand(makeSessionRequest(command, args)).response as TResponse["body"];
    }

    export function openFilesForSession(files: ReadonlyArray<File | { readonly file: File | string, readonly projectRootPath: string }>, session: server.Session): void {
        for (const file of files) {
            session.executeCommand(makeSessionRequest<protocol.OpenRequestArgs>(CommandNames.Open,
                "projectRootPath" in file ? { file: typeof file.file === "string" ? file.file : file.file.path, projectRootPath: file.projectRootPath } : { file: file.path }));
        }
    }

    export function closeFilesForSession(files: ReadonlyArray<File>, session: server.Session): void {
        for (const file of files) {
            session.executeCommand(makeSessionRequest<protocol.FileRequestArgs>(CommandNames.Close, { file: file.path }));
        }
    }

    interface ErrorInformation {
        diagnosticMessage: DiagnosticMessage;
        errorTextArguments?: string[];
    }

    function getProtocolDiagnosticMessage({ diagnosticMessage, errorTextArguments = [] }: ErrorInformation) {
        return formatStringFromArgs(diagnosticMessage.message, errorTextArguments);
    }

    function verifyDiagnostics(actual: server.protocol.Diagnostic[], expected: ErrorInformation[]) {
        const expectedErrors = expected.map(getProtocolDiagnosticMessage);
        assert.deepEqual(actual.map(diag => flattenDiagnosticMessageText(diag.text, "\n")), expectedErrors);
    }

    function verifyNoDiagnostics(actual: server.protocol.Diagnostic[]) {
        verifyDiagnostics(actual, []);
    }

    function checkErrorMessage(session: TestSession, eventName: protocol.DiagnosticEventKind, diagnostics: protocol.DiagnosticEventBody, isMostRecent = false): void {
        checkNthEvent(session, server.toEvent(eventName, diagnostics), 0, isMostRecent);
    }

    function createDiagnostic(start: protocol.Location, end: protocol.Location, message: DiagnosticMessage, args: ReadonlyArray<string> = [], category = diagnosticCategoryName(message), reportsUnnecessary?: {}, relatedInformation?: protocol.DiagnosticRelatedInformation[]): protocol.Diagnostic {
        return { start, end, text: formatStringFromArgs(message.message, args), code: message.code, category, reportsUnnecessary, relatedInformation, source: undefined };
    }

    function checkCompleteEvent(session: TestSession, numberOfCurrentEvents: number, expectedSequenceId: number, isMostRecent = true): void {
        checkNthEvent(session, server.toEvent("requestCompleted", { request_seq: expectedSequenceId }), numberOfCurrentEvents - 1, isMostRecent);
    }

    function checkProjectUpdatedInBackgroundEvent(session: TestSession, openFiles: string[]) {
        checkNthEvent(session, server.toEvent("projectsUpdatedInBackground", { openFiles }), 0, /*isMostRecent*/ true);
    }

    function checkNoDiagnosticEvents(session: TestSession) {
        for (const event of session.events) {
            assert.isFalse(event.event.endsWith("Diag"), JSON.stringify(event));
        }
    }

    function checkNthEvent(session: TestSession, expectedEvent: protocol.Event, index: number, isMostRecent: boolean) {
        const events = session.events;
        assert.deepEqual(events[index], expectedEvent, `Expected ${JSON.stringify(expectedEvent)} at ${index} in ${JSON.stringify(events)}`);

        const outputs = session.host.getOutput();
        assert.equal(outputs[index], server.formatMessage(expectedEvent, nullLogger, Utils.byteLength, session.host.newLine));

        if (isMostRecent) {
            assert.strictEqual(events.length, index + 1, JSON.stringify(events));
            assert.strictEqual(outputs.length, index + 1, JSON.stringify(outputs));
        }
    }

    describe("tsserverProjectSystem general functionality", () => {
        const commonFile1: File = {
            path: "/a/b/commonFile1.ts",
            content: "let x = 1"
        };
        const commonFile2: File = {
            path: "/a/b/commonFile2.ts",
            content: "let y = 1"
        };

        it("create inferred project", () => {
            const appFile: File = {
                path: "/a/b/c/app.ts",
                content: `
                import {f} from "./module"
                console.log(f)
                `
            };

            const moduleFile: File = {
                path: "/a/b/c/module.d.ts",
                content: `export let x: number`
            };
            const host = createServerHost([appFile, moduleFile, libFile]);
            const projectService = createProjectService(host);
            const { configFileName } = projectService.openClientFile(appFile.path);

            assert(!configFileName, `should not find config, got: '${configFileName}`);
            checkNumberOfConfiguredProjects(projectService, 0);
            checkNumberOfInferredProjects(projectService, 1);

            const project = projectService.inferredProjects[0];

            checkArray("inferred project", project.getFileNames(), [appFile.path, libFile.path, moduleFile.path]);
            const configFileLocations = ["/a/b/c/", "/a/b/", "/a/", "/"];
            const configFiles = flatMap(configFileLocations, location => [location + "tsconfig.json", location + "jsconfig.json"]);
            checkWatchedFiles(host, configFiles.concat(libFile.path, moduleFile.path));
            checkWatchedDirectories(host, [], /*recursive*/ false);
            checkWatchedDirectories(host, ["/a/b/c", combinePaths(getDirectoryPath(appFile.path), nodeModulesAtTypes)], /*recursive*/ true);
        });

        it("can handle tsconfig file name with difference casing", () => {
            const f1 = {
                path: "/a/b/app.ts",
                content: "let x = 1"
            };
            const config = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({
                    include: []
                })
            };

            const host = createServerHost([f1, config], { useCaseSensitiveFileNames: false });
            const service = createProjectService(host);
            const upperCaseConfigFilePath = combinePaths(getDirectoryPath(config.path).toUpperCase(), getBaseFileName(config.path));
            service.openExternalProject(<protocol.ExternalProject>{
                projectFileName: "/a/b/project.csproj",
                rootFiles: toExternalFiles([f1.path, upperCaseConfigFilePath]),
                options: {}
            });
            service.checkNumberOfProjects({ configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(service, 0), [upperCaseConfigFilePath]);

            service.openClientFile(f1.path);
            service.checkNumberOfProjects({ configuredProjects: 1, inferredProjects: 1 });

            checkProjectActualFiles(configuredProjectAt(service, 0), [upperCaseConfigFilePath]);
            checkProjectActualFiles(service.inferredProjects[0], [f1.path]);
        });

        it("create configured project without file list", () => {
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `
                {
                    "compilerOptions": {},
                    "exclude": [
                        "e"
                    ]
                }`
            };
            const file1: File = {
                path: "/a/b/c/f1.ts",
                content: "let x = 1"
            };
            const file2: File = {
                path: "/a/b/d/f2.ts",
                content: "let y = 1"
            };
            const file3: File = {
                path: "/a/b/e/f3.ts",
                content: "let z = 1"
            };

            const host = createServerHost([configFile, libFile, file1, file2, file3]);
            const projectService = createProjectService(host);
            const { configFileName, configFileErrors } = projectService.openClientFile(file1.path);

            assert(configFileName, "should find config file");
            assert.isTrue(!configFileErrors || configFileErrors.length === 0, `expect no errors in config file, got ${JSON.stringify(configFileErrors)}`);
            checkNumberOfInferredProjects(projectService, 0);
            checkNumberOfConfiguredProjects(projectService, 1);

            const project = configuredProjectAt(projectService, 0);
            checkProjectActualFiles(project, [file1.path, libFile.path, file2.path, configFile.path]);
            checkProjectRootFiles(project, [file1.path, file2.path]);
            // watching all files except one that was open
            checkWatchedFiles(host, [configFile.path, file2.path, libFile.path]);
            const configFileDirectory = getDirectoryPath(configFile.path);
            checkWatchedDirectories(host, [configFileDirectory, combinePaths(configFileDirectory, nodeModulesAtTypes)], /*recursive*/ true);
        });

        it("create configured project with the file list", () => {
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `
                {
                    "compilerOptions": {},
                    "include": ["*.ts"]
                }`
            };
            const file1: File = {
                path: "/a/b/f1.ts",
                content: "let x = 1"
            };
            const file2: File = {
                path: "/a/b/f2.ts",
                content: "let y = 1"
            };
            const file3: File = {
                path: "/a/b/c/f3.ts",
                content: "let z = 1"
            };

            const host = createServerHost([configFile, libFile, file1, file2, file3]);
            const projectService = createProjectService(host);
            const { configFileName, configFileErrors } = projectService.openClientFile(file1.path);

            assert(configFileName, "should find config file");
            assert.isTrue(!configFileErrors || configFileErrors.length === 0, `expect no errors in config file, got ${JSON.stringify(configFileErrors)}`);
            checkNumberOfInferredProjects(projectService, 0);
            checkNumberOfConfiguredProjects(projectService, 1);

            const project = configuredProjectAt(projectService, 0);
            checkProjectActualFiles(project, [file1.path, libFile.path, file2.path, configFile.path]);
            checkProjectRootFiles(project, [file1.path, file2.path]);
            // watching all files except one that was open
            checkWatchedFiles(host, [configFile.path, file2.path, libFile.path]);
            checkWatchedDirectories(host, [getDirectoryPath(configFile.path)], /*recursive*/ false);
        });

        it("add and then remove a config file in a folder with loose files", () => {
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "files": ["commonFile1.ts"]
                }`
            };
            const filesWithoutConfig = [libFile, commonFile1, commonFile2];
            const host = createServerHost(filesWithoutConfig);

            const filesWithConfig = [libFile, commonFile1, commonFile2, configFile];
            const projectService = createProjectService(host);
            projectService.openClientFile(commonFile1.path);
            projectService.openClientFile(commonFile2.path);

            projectService.checkNumberOfProjects({ inferredProjects: 2 });
            checkProjectActualFiles(projectService.inferredProjects[0], [commonFile1.path, libFile.path]);
            checkProjectActualFiles(projectService.inferredProjects[1], [commonFile2.path, libFile.path]);

            const configFileLocations = ["/", "/a/", "/a/b/"];
            const watchedFiles = flatMap(configFileLocations, location => [location + "tsconfig.json", location + "jsconfig.json"]).concat(libFile.path);
            checkWatchedFiles(host, watchedFiles);

            // Add a tsconfig file
            host.reloadFS(filesWithConfig);
            host.checkTimeoutQueueLengthAndRun(1);

            projectService.checkNumberOfProjects({ inferredProjects: 2, configuredProjects: 1 });
            assert.isTrue(projectService.inferredProjects[0].isOrphan());
            checkProjectActualFiles(projectService.inferredProjects[1], [commonFile2.path, libFile.path]);
            checkProjectActualFiles(projectService.configuredProjects.get(configFile.path)!, [libFile.path, commonFile1.path, configFile.path]);

            checkWatchedFiles(host, watchedFiles);

            // remove the tsconfig file
            host.reloadFS(filesWithoutConfig);

            projectService.checkNumberOfProjects({ inferredProjects: 2 });
            assert.isTrue(projectService.inferredProjects[0].isOrphan());
            checkProjectActualFiles(projectService.inferredProjects[1], [commonFile2.path, libFile.path]);

            host.checkTimeoutQueueLengthAndRun(1); // Refresh inferred projects

            projectService.checkNumberOfProjects({ inferredProjects: 2 });
            checkProjectActualFiles(projectService.inferredProjects[0], [commonFile1.path, libFile.path]);
            checkProjectActualFiles(projectService.inferredProjects[1], [commonFile2.path, libFile.path]);
            checkWatchedFiles(host, watchedFiles);
        });

        it("add new files to a configured project without file list", () => {
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `{}`
            };
            const host = createServerHost([commonFile1, libFile, configFile]);
            const projectService = createProjectService(host);
            projectService.openClientFile(commonFile1.path);
            const configFileDir = getDirectoryPath(configFile.path);
            checkWatchedDirectories(host, [configFileDir, combinePaths(configFileDir, nodeModulesAtTypes)], /*recursive*/ true);
            checkNumberOfConfiguredProjects(projectService, 1);

            const project = configuredProjectAt(projectService, 0);
            checkProjectRootFiles(project, [commonFile1.path]);

            // add a new ts file
            host.reloadFS([commonFile1, commonFile2, libFile, configFile]);
            host.checkTimeoutQueueLengthAndRun(2);
            // project service waits for 250ms to update the project structure, therefore the assertion needs to wait longer.
            checkProjectRootFiles(project, [commonFile1.path, commonFile2.path]);
        });

        it("should ignore non-existing files specified in the config file", () => {
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {},
                    "files": [
                        "commonFile1.ts",
                        "commonFile3.ts"
                    ]
                }`
            };
            const host = createServerHost([commonFile1, commonFile2, configFile]);
            const projectService = createProjectService(host);
            projectService.openClientFile(commonFile1.path);
            projectService.openClientFile(commonFile2.path);

            checkNumberOfConfiguredProjects(projectService, 1);
            const project = configuredProjectAt(projectService, 0);
            checkProjectRootFiles(project, [commonFile1.path]);
            checkNumberOfInferredProjects(projectService, 1);
        });

        it("remove not-listed external projects", () => {
            const f1 = {
                path: "/a/app.ts",
                content: "let x = 1"
            };
            const f2 = {
                path: "/b/app.ts",
                content: "let x = 1"
            };
            const f3 = {
                path: "/c/app.ts",
                content: "let x = 1"
            };
            const makeProject = (f: File) => ({ projectFileName: f.path + ".csproj", rootFiles: [toExternalFile(f.path)], options: {} });
            const p1 = makeProject(f1);
            const p2 = makeProject(f2);
            const p3 = makeProject(f3);

            const host = createServerHost([f1, f2, f3]);
            const session = createSession(host);

            session.executeCommand(<protocol.OpenExternalProjectsRequest>{
                seq: 1,
                type: "request",
                command: "openExternalProjects",
                arguments: { projects: [p1, p2] }
            });

            const projectService = session.getProjectService();
            checkNumberOfProjects(projectService, { externalProjects: 2 });
            assert.equal(projectService.externalProjects[0].getProjectName(), p1.projectFileName);
            assert.equal(projectService.externalProjects[1].getProjectName(), p2.projectFileName);

            session.executeCommand(<protocol.OpenExternalProjectsRequest>{
                seq: 2,
                type: "request",
                command: "openExternalProjects",
                arguments: { projects: [p1, p3] }
            });
            checkNumberOfProjects(projectService, { externalProjects: 2 });
            assert.equal(projectService.externalProjects[0].getProjectName(), p1.projectFileName);
            assert.equal(projectService.externalProjects[1].getProjectName(), p3.projectFileName);

            session.executeCommand(<protocol.OpenExternalProjectsRequest>{
                seq: 3,
                type: "request",
                command: "openExternalProjects",
                arguments: { projects: [] }
            });
            checkNumberOfProjects(projectService, { externalProjects: 0 });

            session.executeCommand(<protocol.OpenExternalProjectsRequest>{
                seq: 3,
                type: "request",
                command: "openExternalProjects",
                arguments: { projects: [p2] }
            });
            assert.equal(projectService.externalProjects[0].getProjectName(), p2.projectFileName);
        });

        it("handle recreated files correctly", () => {
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `{}`
            };
            const host = createServerHost([commonFile1, commonFile2, configFile]);
            const projectService = createProjectService(host);
            projectService.openClientFile(commonFile1.path);

            checkNumberOfConfiguredProjects(projectService, 1);
            const project = configuredProjectAt(projectService, 0);
            checkProjectRootFiles(project, [commonFile1.path, commonFile2.path]);

            // delete commonFile2
            host.reloadFS([commonFile1, configFile]);
            host.checkTimeoutQueueLengthAndRun(2);
            checkProjectRootFiles(project, [commonFile1.path]);

            // re-add commonFile2
            host.reloadFS([commonFile1, commonFile2, configFile]);
            host.checkTimeoutQueueLengthAndRun(2);
            checkProjectRootFiles(project, [commonFile1.path, commonFile2.path]);
        });

        it("handles the missing files - that were added to program because they were added with ///<ref", () => {
            const file1: File = {
                path: "/a/b/commonFile1.ts",
                content: `/// <reference path="commonFile2.ts"/>
                    let x = y`
            };
            const host = createServerHost([file1, libFile]);
            const session = createSession(host);
            openFilesForSession([file1], session);
            const projectService = session.getProjectService();

            checkNumberOfInferredProjects(projectService, 1);
            const project = projectService.inferredProjects[0];
            checkProjectRootFiles(project, [file1.path]);
            checkProjectActualFiles(project, [file1.path, libFile.path]);
            const getErrRequest = makeSessionRequest<server.protocol.SemanticDiagnosticsSyncRequestArgs>(
                server.CommandNames.SemanticDiagnosticsSync,
                { file: file1.path }
            );

            // Two errors: CommonFile2 not found and cannot find name y
            let diags = session.executeCommand(getErrRequest).response as server.protocol.Diagnostic[];
            verifyDiagnostics(diags, [
                { diagnosticMessage: Diagnostics.Cannot_find_name_0, errorTextArguments: ["y"] },
                { diagnosticMessage: Diagnostics.File_0_not_found, errorTextArguments: [commonFile2.path] }
            ]);

            host.reloadFS([file1, commonFile2, libFile]);
            host.runQueuedTimeoutCallbacks();
            checkNumberOfInferredProjects(projectService, 1);
            assert.strictEqual(projectService.inferredProjects[0], project, "Inferred project should be same");
            checkProjectRootFiles(project, [file1.path]);
            checkProjectActualFiles(project, [file1.path, libFile.path, commonFile2.path]);
            diags = session.executeCommand(getErrRequest).response as server.protocol.Diagnostic[];
            verifyNoDiagnostics(diags);
        });

        it("should create new inferred projects for files excluded from a configured project", () => {
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {},
                    "files": ["${commonFile1.path}", "${commonFile2.path}"]
                }`
            };
            const files = [commonFile1, commonFile2, configFile];
            const host = createServerHost(files);
            const projectService = createProjectService(host);
            projectService.openClientFile(commonFile1.path);

            const project = configuredProjectAt(projectService, 0);
            checkProjectRootFiles(project, [commonFile1.path, commonFile2.path]);
            configFile.content = `{
                "compilerOptions": {},
                "files": ["${commonFile1.path}"]
            }`;
            host.reloadFS(files);

            checkNumberOfConfiguredProjects(projectService, 1);
            checkProjectRootFiles(project, [commonFile1.path, commonFile2.path]);
            host.checkTimeoutQueueLengthAndRun(2); // Update the configured project + refresh inferred projects
            checkNumberOfConfiguredProjects(projectService, 1);
            checkProjectRootFiles(project, [commonFile1.path]);

            projectService.openClientFile(commonFile2.path);
            checkNumberOfInferredProjects(projectService, 1);
        });

        it("files explicitly excluded in config file", () => {
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {},
                    "exclude": ["/a/c"]
                }`
            };
            const excludedFile1: File = {
                path: "/a/c/excluedFile1.ts",
                content: `let t = 1;`
            };

            const host = createServerHost([commonFile1, commonFile2, excludedFile1, configFile]);
            const projectService = createProjectService(host);

            projectService.openClientFile(commonFile1.path);
            checkNumberOfConfiguredProjects(projectService, 1);
            const project = configuredProjectAt(projectService, 0);
            checkProjectRootFiles(project, [commonFile1.path, commonFile2.path]);
            projectService.openClientFile(excludedFile1.path);
            checkNumberOfInferredProjects(projectService, 1);
        });

        it("should properly handle module resolution changes in config file", () => {
            const file1: File = {
                path: "/a/b/file1.ts",
                content: `import { T } from "module1";`
            };
            const nodeModuleFile: File = {
                path: "/a/b/node_modules/module1.ts",
                content: `export interface T {}`
            };
            const classicModuleFile: File = {
                path: "/a/module1.ts",
                content: `export interface T {}`
            };
            const randomFile: File = {
                path: "/a/file1.ts",
                content: `export interface T {}`
            };
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {
                        "moduleResolution": "node"
                    },
                    "files": ["${file1.path}"]
                }`
            };
            const files = [file1, nodeModuleFile, classicModuleFile, configFile, randomFile];
            const host = createServerHost(files);
            const projectService = createProjectService(host);
            projectService.openClientFile(file1.path);
            projectService.openClientFile(nodeModuleFile.path);
            projectService.openClientFile(classicModuleFile.path);

            checkNumberOfProjects(projectService, { configuredProjects: 1, inferredProjects: 1 });
            const project = configuredProjectAt(projectService, 0);
            const inferredProject0 = projectService.inferredProjects[0];
            checkProjectActualFiles(project, [file1.path, nodeModuleFile.path, configFile.path]);
            checkProjectActualFiles(projectService.inferredProjects[0], [classicModuleFile.path]);

            configFile.content = `{
                "compilerOptions": {
                    "moduleResolution": "classic"
                },
                "files": ["${file1.path}"]
            }`;
            host.reloadFS(files);
            host.checkTimeoutQueueLengthAndRun(2);

            checkNumberOfProjects(projectService, { configuredProjects: 1, inferredProjects: 2 }); // will not remove project 1
            checkProjectActualFiles(project, [file1.path, classicModuleFile.path, configFile.path]);
            assert.strictEqual(projectService.inferredProjects[0], inferredProject0);
            assert.isTrue(projectService.inferredProjects[0].isOrphan());
            const inferredProject1 = projectService.inferredProjects[1];
            checkProjectActualFiles(projectService.inferredProjects[1], [nodeModuleFile.path]);

            // Open random file and it will reuse first inferred project
            projectService.openClientFile(randomFile.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1, inferredProjects: 2 });
            checkProjectActualFiles(project, [file1.path, classicModuleFile.path, configFile.path]);
            assert.strictEqual(projectService.inferredProjects[0], inferredProject0);
            checkProjectActualFiles(projectService.inferredProjects[0], [randomFile.path]); // Reuses first inferred project
            assert.strictEqual(projectService.inferredProjects[1], inferredProject1);
            checkProjectActualFiles(projectService.inferredProjects[1], [nodeModuleFile.path]);
        });

        it("should keep the configured project when the opened file is referenced by the project but not its root", () => {
            const file1: File = {
                path: "/a/b/main.ts",
                content: "import { objA } from './obj-a';"
            };
            const file2: File = {
                path: "/a/b/obj-a.ts",
                content: `export const objA = Object.assign({foo: "bar"}, {bar: "baz"});`
            };
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {
                        "target": "es6"
                    },
                    "files": [ "main.ts" ]
                }`
            };
            const host = createServerHost([file1, file2, configFile]);
            const projectService = createProjectService(host);
            projectService.openClientFile(file1.path);
            projectService.closeClientFile(file1.path);
            projectService.openClientFile(file2.path);
            checkNumberOfConfiguredProjects(projectService, 1);
            checkNumberOfInferredProjects(projectService, 0);
        });

        it("should keep the configured project when the opened file is referenced by the project but not its root", () => {
            const file1: File = {
                path: "/a/b/main.ts",
                content: "import { objA } from './obj-a';"
            };
            const file2: File = {
                path: "/a/b/obj-a.ts",
                content: `export const objA = Object.assign({foo: "bar"}, {bar: "baz"});`
            };
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {
                        "target": "es6"
                    },
                    "files": [ "main.ts" ]
                }`
            };
            const host = createServerHost([file1, file2, configFile]);
            const projectService = createProjectService(host);
            projectService.openClientFile(file1.path);
            projectService.closeClientFile(file1.path);
            projectService.openClientFile(file2.path);
            checkNumberOfConfiguredProjects(projectService, 1);
            checkNumberOfInferredProjects(projectService, 0);
        });
        it("should tolerate config file errors and still try to build a project", () => {
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {
                        "target": "es6",
                        "allowAnything": true
                    },
                    "someOtherProperty": {}
                }`
            };
            const host = createServerHost([commonFile1, commonFile2, libFile, configFile]);
            const projectService = createProjectService(host);
            projectService.openClientFile(commonFile1.path);
            checkNumberOfConfiguredProjects(projectService, 1);
            checkProjectRootFiles(configuredProjectAt(projectService, 0), [commonFile1.path, commonFile2.path]);
        });

        it("should disable features when the files are too large", () => {
            const file1 = {
                path: "/a/b/f1.js",
                content: "let x =1;",
                fileSize: 10 * 1024 * 1024
            };
            const file2 = {
                path: "/a/b/f2.js",
                content: "let y =1;",
                fileSize: 6 * 1024 * 1024
            };
            const file3 = {
                path: "/a/b/f3.js",
                content: "let y =1;",
                fileSize: 6 * 1024 * 1024
            };

            const proj1name = "proj1", proj2name = "proj2", proj3name = "proj3";

            const host = createServerHost([file1, file2, file3]);
            const projectService = createProjectService(host);

            projectService.openExternalProject({ rootFiles: toExternalFiles([file1.path]), options: {}, projectFileName: proj1name });
            const proj1 = projectService.findProject(proj1name)!;
            assert.isTrue(proj1.languageServiceEnabled);

            projectService.openExternalProject({ rootFiles: toExternalFiles([file2.path]), options: {}, projectFileName: proj2name });
            const proj2 = projectService.findProject(proj2name)!;
            assert.isTrue(proj2.languageServiceEnabled);

            projectService.openExternalProject({ rootFiles: toExternalFiles([file3.path]), options: {}, projectFileName: proj3name });
            const proj3 = projectService.findProject(proj3name)!;
            assert.isFalse(proj3.languageServiceEnabled);
        });

        it("should use only one inferred project if 'useOneInferredProject' is set", () => {
            const file1 = {
                path: "/a/b/main.ts",
                content: "let x =1;"
            };
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {
                        "target": "es6"
                    },
                    "files": [ "main.ts" ]
                }`
            };
            const file2 = {
                path: "/a/c/main.ts",
                content: "let x =1;"
            };

            const file3 = {
                path: "/a/d/main.ts",
                content: "let x =1;"
            };

            const host = createServerHost([file1, file2, file3, libFile]);
            const projectService = createProjectService(host, { useSingleInferredProject: true });
            projectService.openClientFile(file1.path);
            projectService.openClientFile(file2.path);
            projectService.openClientFile(file3.path);

            checkNumberOfConfiguredProjects(projectService, 0);
            checkNumberOfInferredProjects(projectService, 1);
            checkProjectActualFiles(projectService.inferredProjects[0], [file1.path, file2.path, file3.path, libFile.path]);


            host.reloadFS([file1, configFile, file2, file3, libFile]);
            host.checkTimeoutQueueLengthAndRun(1);
            checkNumberOfConfiguredProjects(projectService, 1);
            checkNumberOfInferredProjects(projectService, 1);
            checkProjectActualFiles(projectService.inferredProjects[0], [file2.path, file3.path, libFile.path]);
        });

        it("should reuse same project if file is opened from the configured project that has no open files", () => {
            const file1 = {
                path: "/a/b/main.ts",
                content: "let x =1;"
            };
            const file2 = {
                path: "/a/b/main2.ts",
                content: "let y =1;"
            };
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {
                        "target": "es6"
                    },
                    "files": [ "main.ts", "main2.ts" ]
                }`
            };
            const host = createServerHost([file1, file2, configFile, libFile]);
            const projectService = createProjectService(host, { useSingleInferredProject: true });
            projectService.openClientFile(file1.path);
            checkNumberOfConfiguredProjects(projectService, 1);
            const project = projectService.configuredProjects.get(configFile.path)!;
            assert.isTrue(project.hasOpenRef()); // file1

            projectService.closeClientFile(file1.path);
            checkNumberOfConfiguredProjects(projectService, 1);
            assert.strictEqual(projectService.configuredProjects.get(configFile.path), project);
            assert.isFalse(project.hasOpenRef()); // No open files
            assert.isFalse(project.isClosed());

            projectService.openClientFile(file2.path);
            checkNumberOfConfiguredProjects(projectService, 1);
            assert.strictEqual(projectService.configuredProjects.get(configFile.path), project);
            assert.isTrue(project.hasOpenRef()); // file2
            assert.isFalse(project.isClosed());
        });

        it("should not close configured project after closing last open file, but should be closed on next file open if its not the file from same project", () => {
            const file1 = {
                path: "/a/b/main.ts",
                content: "let x =1;"
            };
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {
                        "target": "es6"
                    },
                    "files": [ "main.ts" ]
                }`
            };
            const host = createServerHost([file1, configFile, libFile]);
            const projectService = createProjectService(host, { useSingleInferredProject: true });
            projectService.openClientFile(file1.path);
            checkNumberOfConfiguredProjects(projectService, 1);
            const project = projectService.configuredProjects.get(configFile.path)!;
            assert.isTrue(project.hasOpenRef()); // file1

            projectService.closeClientFile(file1.path);
            checkNumberOfConfiguredProjects(projectService, 1);
            assert.strictEqual(projectService.configuredProjects.get(configFile.path), project);
            assert.isFalse(project.hasOpenRef()); // No files
            assert.isFalse(project.isClosed());

            projectService.openClientFile(libFile.path);
            checkNumberOfConfiguredProjects(projectService, 0);
            assert.isFalse(project.hasOpenRef()); // No files + project closed
            assert.isTrue(project.isClosed());
        });

        it("should not close external project with no open files", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: "let x =1;"
            };
            const file2 = {
                path: "/a/b/f2.ts",
                content: "let y =1;"
            };
            const externalProjectName = "externalproject";
            const host = createServerHost([file1, file2]);
            const projectService = createProjectService(host);
            projectService.openExternalProject({
                rootFiles: toExternalFiles([file1.path, file2.path]),
                options: {},
                projectFileName: externalProjectName
            });

            checkNumberOfExternalProjects(projectService, 1);
            checkNumberOfInferredProjects(projectService, 0);

            // open client file - should not lead to creation of inferred project
            projectService.openClientFile(file1.path, file1.content);
            checkNumberOfExternalProjects(projectService, 1);
            checkNumberOfInferredProjects(projectService, 0);

            // close client file - external project should still exists
            projectService.closeClientFile(file1.path);
            checkNumberOfExternalProjects(projectService, 1);
            checkNumberOfInferredProjects(projectService, 0);

            projectService.closeExternalProject(externalProjectName);
            checkNumberOfExternalProjects(projectService, 0);
            checkNumberOfInferredProjects(projectService, 0);
        });

        it("external project for dynamic file", () => {
            const externalProjectName = "^ScriptDocument1 file1.ts";
            const externalFiles = toExternalFiles(["^ScriptDocument1 file1.ts"]);
            const host = createServerHost([]);
            const projectService = createProjectService(host);
            projectService.openExternalProject({
                rootFiles: externalFiles,
                options: {},
                projectFileName: externalProjectName
            });

            checkNumberOfExternalProjects(projectService, 1);
            checkNumberOfInferredProjects(projectService, 0);

            externalFiles[0].content = "let x =1;";
            projectService.applyChangesInOpenFiles(externalFiles, [], []);
        });

        it("external project that included config files", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: "let x =1;"
            };
            const config1 = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify(
                    {
                        compilerOptions: {},
                        files: ["f1.ts"]
                    }
                )
            };
            const file2 = {
                path: "/a/c/f2.ts",
                content: "let y =1;"
            };
            const config2 = {
                path: "/a/c/tsconfig.json",
                content: JSON.stringify(
                    {
                        compilerOptions: {},
                        files: ["f2.ts"]
                    }
                )
            };
            const file3 = {
                path: "/a/d/f3.ts",
                content: "let z =1;"
            };
            const externalProjectName = "externalproject";
            const host = createServerHost([file1, file2, file3, config1, config2]);
            const projectService = createProjectService(host);
            projectService.openExternalProject({
                rootFiles: toExternalFiles([config1.path, config2.path, file3.path]),
                options: {},
                projectFileName: externalProjectName
            });

            checkNumberOfProjects(projectService, { configuredProjects: 2 });
            const proj1 = projectService.configuredProjects.get(config1.path);
            const proj2 = projectService.configuredProjects.get(config2.path);
            assert.isDefined(proj1);
            assert.isDefined(proj2);

            // open client file - should not lead to creation of inferred project
            projectService.openClientFile(file1.path, file1.content);
            checkNumberOfProjects(projectService, { configuredProjects: 2 });
            assert.strictEqual(projectService.configuredProjects.get(config1.path), proj1);
            assert.strictEqual(projectService.configuredProjects.get(config2.path), proj2);

            projectService.openClientFile(file3.path, file3.content);
            checkNumberOfProjects(projectService, { configuredProjects: 2, inferredProjects: 1 });
            assert.strictEqual(projectService.configuredProjects.get(config1.path), proj1);
            assert.strictEqual(projectService.configuredProjects.get(config2.path), proj2);

            projectService.closeExternalProject(externalProjectName);
            // open file 'file1' from configured project keeps project alive
            checkNumberOfProjects(projectService, { configuredProjects: 1, inferredProjects: 1 });
            assert.strictEqual(projectService.configuredProjects.get(config1.path), proj1);
            assert.isUndefined(projectService.configuredProjects.get(config2.path));

            projectService.closeClientFile(file3.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1, inferredProjects: 1 });
            assert.strictEqual(projectService.configuredProjects.get(config1.path), proj1);
            assert.isUndefined(projectService.configuredProjects.get(config2.path));
            assert.isTrue(projectService.inferredProjects[0].isOrphan());

            projectService.closeClientFile(file1.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1, inferredProjects: 1 });
            assert.strictEqual(projectService.configuredProjects.get(config1.path), proj1);
            assert.isUndefined(projectService.configuredProjects.get(config2.path));
            assert.isTrue(projectService.inferredProjects[0].isOrphan());

            projectService.openClientFile(file2.path, file2.content);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            assert.isUndefined(projectService.configuredProjects.get(config1.path));
            assert.isDefined(projectService.configuredProjects.get(config2.path));
        });

        describe("ignoreConfigFiles", () => {
            it("external project including config file", () => {
                const file1 = {
                    path: "/a/b/f1.ts",
                    content: "let x =1;"
                };
                const config1 = {
                    path: "/a/b/tsconfig.json",
                    content: JSON.stringify(
                        {
                            compilerOptions: {},
                            files: ["f1.ts"]
                        }
                    )
                };

                const externalProjectName = "externalproject";
                const host = createServerHost([file1, config1]);
                const projectService = createProjectService(host, { useSingleInferredProject: true }, { syntaxOnly: true });
                projectService.openExternalProject({
                    rootFiles: toExternalFiles([file1.path, config1.path]),
                    options: {},
                    projectFileName: externalProjectName
                });

                checkNumberOfProjects(projectService, { externalProjects: 1 });
                const proj = projectService.externalProjects[0];
                assert.isDefined(proj);

                assert.isTrue(proj.fileExists(file1.path));
            });

            it("loose file included in config file (openClientFile)", () => {
                const file1 = {
                    path: "/a/b/f1.ts",
                    content: "let x =1;"
                };
                const config1 = {
                    path: "/a/b/tsconfig.json",
                    content: JSON.stringify(
                        {
                            compilerOptions: {},
                            files: ["f1.ts"]
                        }
                    )
                };

                const host = createServerHost([file1, config1]);
                const projectService = createProjectService(host, { useSingleInferredProject: true }, { syntaxOnly: true });
                projectService.openClientFile(file1.path, file1.content);

                checkNumberOfProjects(projectService, { inferredProjects: 1 });
                const proj = projectService.inferredProjects[0];
                assert.isDefined(proj);

                assert.isTrue(proj.fileExists(file1.path));
            });

            it("loose file included in config file (applyCodeChanges)", () => {
                const file1 = {
                    path: "/a/b/f1.ts",
                    content: "let x =1;"
                };
                const config1 = {
                    path: "/a/b/tsconfig.json",
                    content: JSON.stringify(
                        {
                            compilerOptions: {},
                            files: ["f1.ts"]
                        }
                    )
                };

                const host = createServerHost([file1, config1]);
                const projectService = createProjectService(host, { useSingleInferredProject: true }, { syntaxOnly: true });
                projectService.applyChangesInOpenFiles([{ fileName: file1.path, content: file1.content }], [], []);

                checkNumberOfProjects(projectService, { inferredProjects: 1 });
                const proj = projectService.inferredProjects[0];
                assert.isDefined(proj);

                assert.isTrue(proj.fileExists(file1.path));
            });
        });

        it("disable inferred project", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: "let x =1;"
            };

            const host = createServerHost([file1]);
            const projectService = createProjectService(host, { useSingleInferredProject: true }, { syntaxOnly: true });

            projectService.openClientFile(file1.path, file1.content);

            checkNumberOfProjects(projectService, { inferredProjects: 1 });
            const proj = projectService.inferredProjects[0];
            assert.isDefined(proj);

            assert.isFalse(proj.languageServiceEnabled);
        });

        it("reload regular file after closing", () => {
            const f1 = {
                path: "/a/b/app.ts",
                content: "x."
            };
            const f2 = {
                path: "/a/b/lib.ts",
                content: "let x: number;"
            };

            const host = createServerHost([f1, f2, libFile]);
            const service = createProjectService(host);
            service.openExternalProject({ projectFileName: "/a/b/project", rootFiles: toExternalFiles([f1.path, f2.path]), options: {} });

            service.openClientFile(f1.path);
            service.openClientFile(f2.path, "let x: string");

            service.checkNumberOfProjects({ externalProjects: 1 });
            checkProjectActualFiles(service.externalProjects[0], [f1.path, f2.path, libFile.path]);

            const completions1 = service.externalProjects[0].getLanguageService().getCompletionsAtPosition(f1.path, 2, emptyOptions)!;
            // should contain completions for string
            assert.isTrue(completions1.entries.some(e => e.name === "charAt"), "should contain 'charAt'");
            assert.isFalse(completions1.entries.some(e => e.name === "toExponential"), "should not contain 'toExponential'");

            service.closeClientFile(f2.path);
            const completions2 = service.externalProjects[0].getLanguageService().getCompletionsAtPosition(f1.path, 2, emptyOptions)!;
            // should contain completions for string
            assert.isFalse(completions2.entries.some(e => e.name === "charAt"), "should not contain 'charAt'");
            assert.isTrue(completions2.entries.some(e => e.name === "toExponential"), "should contain 'toExponential'");
        });

        it("clear mixed content file after closing", () => {
            const f1 = {
                path: "/a/b/app.ts",
                content: " "
            };
            const f2 = {
                path: "/a/b/lib.html",
                content: "<html/>"
            };

            const host = createServerHost([f1, f2, libFile]);
            const service = createProjectService(host);
            service.openExternalProject({ projectFileName: "/a/b/project", rootFiles: [{ fileName: f1.path }, { fileName: f2.path, hasMixedContent: true }], options: {} });

            service.openClientFile(f1.path);
            service.openClientFile(f2.path, "let somelongname: string");

            service.checkNumberOfProjects({ externalProjects: 1 });
            checkProjectActualFiles(service.externalProjects[0], [f1.path, f2.path, libFile.path]);

            const completions1 = service.externalProjects[0].getLanguageService().getCompletionsAtPosition(f1.path, 0, emptyOptions)!;
            assert.isTrue(completions1.entries.some(e => e.name === "somelongname"), "should contain 'somelongname'");

            service.closeClientFile(f2.path);
            const completions2 = service.externalProjects[0].getLanguageService().getCompletionsAtPosition(f1.path, 0, emptyOptions)!;
            assert.isFalse(completions2.entries.some(e => e.name === "somelongname"), "should not contain 'somelongname'");
            const sf2 = service.externalProjects[0].getLanguageService().getProgram()!.getSourceFile(f2.path)!;
            assert.equal(sf2.text, "");
        });


        it("external project with included config file opened after configured project", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: "let x = 1"
            };
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ compilerOptions: {} })
            };
            const externalProjectName = "externalproject";
            const host = createServerHost([file1, configFile]);
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });

            projectService.openExternalProject({
                rootFiles: toExternalFiles([configFile.path]),
                options: {},
                projectFileName: externalProjectName
            });

            checkNumberOfProjects(projectService, { configuredProjects: 1 });

            projectService.closeClientFile(file1.path);
            // configured project is alive since it is opened as part of external project
            checkNumberOfProjects(projectService, { configuredProjects: 1 });

            projectService.closeExternalProject(externalProjectName);
            checkNumberOfProjects(projectService, { configuredProjects: 0 });
        });

        it("external project with included config file opened after configured project and then closed", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: "let x = 1"
            };
            const file2 = {
                path: "/a/f2.ts",
                content: "let x = 1"
            };
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ compilerOptions: {} })
            };
            const externalProjectName = "externalproject";
            const host = createServerHost([file1, file2, libFile, configFile]);
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            const project = projectService.configuredProjects.get(configFile.path);

            projectService.openExternalProject({
                rootFiles: toExternalFiles([configFile.path]),
                options: {},
                projectFileName: externalProjectName
            });

            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            assert.strictEqual(projectService.configuredProjects.get(configFile.path), project);

            projectService.closeExternalProject(externalProjectName);
            // configured project is alive since file is still open
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            assert.strictEqual(projectService.configuredProjects.get(configFile.path), project);

            projectService.closeClientFile(file1.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            assert.strictEqual(projectService.configuredProjects.get(configFile.path), project);

            projectService.openClientFile(file2.path);
            checkNumberOfProjects(projectService, { inferredProjects: 1 });
            assert.isUndefined(projectService.configuredProjects.get(configFile.path));
        });

        it("changes in closed files are reflected in project structure", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: `export * from "./f2"`
            };
            const file2 = {
                path: "/a/b/f2.ts",
                content: `export let x = 1`
            };
            const file3 = {
                path: "/a/c/f3.ts",
                content: `export let y = 1;`
            };
            const host = createServerHost([file1, file2, file3]);
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);
            checkNumberOfProjects(projectService, { inferredProjects: 1 });
            const inferredProject0 = projectService.inferredProjects[0];
            checkProjectActualFiles(projectService.inferredProjects[0], [file1.path, file2.path]);

            projectService.openClientFile(file3.path);
            checkNumberOfProjects(projectService, { inferredProjects: 2 });
            assert.strictEqual(projectService.inferredProjects[0], inferredProject0);
            checkProjectActualFiles(projectService.inferredProjects[0], [file1.path, file2.path]);
            const inferredProject1 = projectService.inferredProjects[1];
            checkProjectActualFiles(projectService.inferredProjects[1], [file3.path]);

            const modifiedFile2 = {
                path: file2.path,
                content: `export * from "../c/f3"` // now inferred project should inclule file3
            };

            host.reloadFS([file1, modifiedFile2, file3]);
            host.checkTimeoutQueueLengthAndRun(2);
            checkNumberOfProjects(projectService, { inferredProjects: 2 });
            assert.strictEqual(projectService.inferredProjects[0], inferredProject0);
            checkProjectActualFiles(projectService.inferredProjects[0], [file1.path, modifiedFile2.path, file3.path]);
            assert.strictEqual(projectService.inferredProjects[1], inferredProject1);
            assert.isTrue(inferredProject1.isOrphan());
        });

        it("deleted files affect project structure", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: `export * from "./f2"`
            };
            const file2 = {
                path: "/a/b/f2.ts",
                content: `export * from "../c/f3"`
            };
            const file3 = {
                path: "/a/c/f3.ts",
                content: `export let y = 1;`
            };
            const host = createServerHost([file1, file2, file3]);
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);

            checkNumberOfProjects(projectService, { inferredProjects: 1 });

            checkProjectActualFiles(projectService.inferredProjects[0], [file1.path, file2.path, file3.path]);

            projectService.openClientFile(file3.path);
            checkNumberOfProjects(projectService, { inferredProjects: 1 });

            host.reloadFS([file1, file3]);
            host.checkTimeoutQueueLengthAndRun(2);

            checkNumberOfProjects(projectService, { inferredProjects: 2 });

            checkProjectActualFiles(projectService.inferredProjects[0], [file1.path]);
            checkProjectActualFiles(projectService.inferredProjects[1], [file3.path]);
        });

        it("ignores files excluded by a custom safe type list", () => {
            const file1 = {
                path: "/a/b/f1.js",
                content: "export let x = 5"
            };
            const office = {
                path: "/lib/duckquack-3.min.js",
                content: "whoa do @@ not parse me ok thanks!!!"
            };
            const host = createServerHost([file1, office, customTypesMap]);
            const projectService = createProjectService(host);
            try {
                projectService.openExternalProject({ projectFileName: "project", options: {}, rootFiles: toExternalFiles([file1.path, office.path]) });
                const proj = projectService.externalProjects[0];
                assert.deepEqual(proj.getFileNames(/*excludeFilesFromExternalLibraries*/ true), [file1.path]);
                assert.deepEqual(proj.getTypeAcquisition().include, ["duck-types"]);
            } finally {
                projectService.resetSafeList();
            }
        });

        it("ignores files excluded by the default type list", () => {
            const file1 = {
                path: "/a/b/f1.js",
                content: "export let x = 5"
            };
            const minFile = {
                path: "/c/moment.min.js",
                content: "unspecified"
            };
            const kendoFile1 = {
                path: "/q/lib/kendo/kendo.all.min.js",
                content: "unspecified"
            };
            const kendoFile2 = {
                path: "/q/lib/kendo/kendo.ui.min.js",
                content: "unspecified"
            };
            const kendoFile3 = {
                path: "/q/lib/kendo-ui/kendo.all.js",
                content: "unspecified"
            };
            const officeFile1 = {
                path: "/scripts/Office/1/excel-15.debug.js",
                content: "unspecified"
            };
            const officeFile2 = {
                path: "/scripts/Office/1/powerpoint.js",
                content: "unspecified"
            };
            const files = [file1, minFile, kendoFile1, kendoFile2, kendoFile3, officeFile1, officeFile2];
            const host = createServerHost(files);
            const projectService = createProjectService(host);
            try {
                projectService.openExternalProject({ projectFileName: "project", options: {}, rootFiles: toExternalFiles(files.map(f => f.path)) });
                const proj = projectService.externalProjects[0];
                assert.deepEqual(proj.getFileNames(/*excludeFilesFromExternalLibraries*/ true), [file1.path]);
                assert.deepEqual(proj.getTypeAcquisition().include, ["kendo-ui", "office"]);
            } finally {
                projectService.resetSafeList();
            }
        });

        it("removes version numbers correctly", () => {
            const testData: [string, string][] = [
                ["jquery-max", "jquery-max"],
                ["jquery.min", "jquery"],
                ["jquery-min.4.2.3", "jquery"],
                ["jquery.min.4.2.1", "jquery"],
                ["minimum", "minimum"],
                ["min", "min"],
                ["min.3.2", "min"],
                ["jquery", "jquery"]
            ];
            for (const t of testData) {
                assert.equal(removeMinAndVersionNumbers(t[0]), t[1], t[0]);
            }
        });

        it("ignores files excluded by a legacy safe type list", () => {
            const file1 = {
                path: "/a/b/bliss.js",
                content: "let x = 5"
            };
            const file2 = {
                path: "/a/b/foo.js",
                content: ""
            };
            const file3 = {
                path: "/a/b/Bacon.js",
                content: "let y = 5"
            };
            const host = createServerHost([file1, file2, file3, customTypesMap]);
            const projectService = createProjectService(host);
            try {
                projectService.openExternalProject({ projectFileName: "project", options: {}, rootFiles: toExternalFiles([file1.path, file2.path]), typeAcquisition: { enable: true } });
                const proj = projectService.externalProjects[0];
                assert.deepEqual(proj.getFileNames(), [file2.path]);
            } finally {
                projectService.resetSafeList();
            }
        });

        it("open file become a part of configured project if it is referenced from root file", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: "export let x = 5"
            };
            const file2 = {
                path: "/a/c/f2.ts",
                content: `import {x} from "../b/f1"`
            };
            const file3 = {
                path: "/a/c/f3.ts",
                content: "export let y = 1"
            };
            const configFile = {
                path: "/a/c/tsconfig.json",
                content: JSON.stringify({ compilerOptions: {}, files: ["f2.ts", "f3.ts"] })
            };

            const host = createServerHost([file1, file2, file3]);
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);
            checkNumberOfProjects(projectService, { inferredProjects: 1 });
            checkProjectActualFiles(projectService.inferredProjects[0], [file1.path]);

            projectService.openClientFile(file3.path);
            checkNumberOfProjects(projectService, { inferredProjects: 2 });
            checkProjectActualFiles(projectService.inferredProjects[0], [file1.path]);
            checkProjectActualFiles(projectService.inferredProjects[1], [file3.path]);

            host.reloadFS([file1, file2, file3, configFile]);
            host.checkTimeoutQueueLengthAndRun(1);
            checkNumberOfProjects(projectService, { configuredProjects: 1, inferredProjects: 2 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [file1.path, file2.path, file3.path, configFile.path]);
            assert.isTrue(projectService.inferredProjects[0].isOrphan());
            assert.isTrue(projectService.inferredProjects[1].isOrphan());
        });

        it("correctly migrate files between projects", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: `
                export * from "../c/f2";
                export * from "../d/f3";`
            };
            const file2 = {
                path: "/a/c/f2.ts",
                content: "export let x = 1;"
            };
            const file3 = {
                path: "/a/d/f3.ts",
                content: "export let y = 1;"
            };
            const host = createServerHost([file1, file2, file3]);
            const projectService = createProjectService(host);

            projectService.openClientFile(file2.path);
            checkNumberOfProjects(projectService, { inferredProjects: 1 });
            checkProjectActualFiles(projectService.inferredProjects[0], [file2.path]);
            let inferredProjects = projectService.inferredProjects.slice();

            projectService.openClientFile(file3.path);
            checkNumberOfProjects(projectService, { inferredProjects: 2 });
            assert.strictEqual(projectService.inferredProjects[0], inferredProjects[0]);
            checkProjectActualFiles(projectService.inferredProjects[0], [file2.path]);
            checkProjectActualFiles(projectService.inferredProjects[1], [file3.path]);
            inferredProjects = projectService.inferredProjects.slice();

            projectService.openClientFile(file1.path);
            checkNumberOfProjects(projectService, { inferredProjects: 1 });
            assert.notStrictEqual(projectService.inferredProjects[0], inferredProjects[0]);
            assert.notStrictEqual(projectService.inferredProjects[0], inferredProjects[1]);
            checkProjectRootFiles(projectService.inferredProjects[0], [file1.path]);
            checkProjectActualFiles(projectService.inferredProjects[0], [file1.path, file2.path, file3.path]);
            inferredProjects = projectService.inferredProjects.slice();

            projectService.closeClientFile(file1.path);
            checkNumberOfProjects(projectService, { inferredProjects: 3 });
            assert.strictEqual(projectService.inferredProjects[0], inferredProjects[0]);
            assert.isTrue(projectService.inferredProjects[0].isOrphan());
            checkProjectActualFiles(projectService.inferredProjects[1], [file2.path]);
            checkProjectActualFiles(projectService.inferredProjects[2], [file3.path]);
            inferredProjects = projectService.inferredProjects.slice();

            projectService.closeClientFile(file3.path);
            checkNumberOfProjects(projectService, { inferredProjects: 3 });
            assert.strictEqual(projectService.inferredProjects[0], inferredProjects[0]);
            assert.strictEqual(projectService.inferredProjects[1], inferredProjects[1]);
            assert.strictEqual(projectService.inferredProjects[2], inferredProjects[2]);
            assert.isTrue(projectService.inferredProjects[0].isOrphan());
            checkProjectActualFiles(projectService.inferredProjects[1], [file2.path]);
            assert.isTrue(projectService.inferredProjects[2].isOrphan());

            projectService.openClientFile(file3.path);
            checkNumberOfProjects(projectService, { inferredProjects: 2 });
            assert.strictEqual(projectService.inferredProjects[0], inferredProjects[2]);
            assert.strictEqual(projectService.inferredProjects[1], inferredProjects[1]);
            checkProjectActualFiles(projectService.inferredProjects[0], [file3.path]);
            checkProjectActualFiles(projectService.inferredProjects[1], [file2.path]);
        });

        it("can correctly update configured project when set of root files has changed (new file on disk)", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: "let x = 1"
            };
            const file2 = {
                path: "/a/b/f2.ts",
                content: "let y = 1"
            };
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ compilerOptions: {} })
            };

            const host = createServerHost([file1, configFile]);
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [file1.path, configFile.path]);

            host.reloadFS([file1, file2, configFile]);

            host.checkTimeoutQueueLengthAndRun(2);

            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            checkProjectRootFiles(configuredProjectAt(projectService, 0), [file1.path, file2.path]);
        });

        it("can correctly update configured project when set of root files has changed (new file in list of files)", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: "let x = 1"
            };
            const file2 = {
                path: "/a/b/f2.ts",
                content: "let y = 1"
            };
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ compilerOptions: {}, files: ["f1.ts"] })
            };

            const host = createServerHost([file1, file2, configFile]);
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [file1.path, configFile.path]);

            const modifiedConfigFile = {
                path: configFile.path,
                content: JSON.stringify({ compilerOptions: {}, files: ["f1.ts", "f2.ts"] })
            };

            host.reloadFS([file1, file2, modifiedConfigFile]);

            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            host.checkTimeoutQueueLengthAndRun(2);
            checkProjectRootFiles(configuredProjectAt(projectService, 0), [file1.path, file2.path]);
        });

        it("can update configured project when set of root files was not changed", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: "let x = 1"
            };
            const file2 = {
                path: "/a/b/f2.ts",
                content: "let y = 1"
            };
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ compilerOptions: {}, files: ["f1.ts", "f2.ts"] })
            };

            const host = createServerHost([file1, file2, configFile]);
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [file1.path, file2.path, configFile.path]);

            const modifiedConfigFile = {
                path: configFile.path,
                content: JSON.stringify({ compilerOptions: { outFile: "out.js" }, files: ["f1.ts", "f2.ts"] })
            };

            host.reloadFS([file1, file2, modifiedConfigFile]);

            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            checkProjectRootFiles(configuredProjectAt(projectService, 0), [file1.path, file2.path]);
        });

        it("can correctly update external project when set of root files has changed", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: "let x = 1"
            };
            const file2 = {
                path: "/a/b/f2.ts",
                content: "let y = 1"
            };
            const host = createServerHost([file1, file2]);
            const projectService = createProjectService(host);

            projectService.openExternalProject({ projectFileName: "project", options: {}, rootFiles: toExternalFiles([file1.path]) });
            checkNumberOfProjects(projectService, { externalProjects: 1 });
            checkProjectActualFiles(projectService.externalProjects[0], [file1.path]);

            projectService.openExternalProject({ projectFileName: "project", options: {}, rootFiles: toExternalFiles([file1.path, file2.path]) });
            checkNumberOfProjects(projectService, { externalProjects: 1 });
            checkProjectRootFiles(projectService.externalProjects[0], [file1.path, file2.path]);
        });

        it("can update external project when set of root files was not changed", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: `export * from "m"`
            };
            const file2 = {
                path: "/a/b/f2.ts",
                content: "export let y = 1"
            };
            const file3 = {
                path: "/a/m.ts",
                content: "export let y = 1"
            };

            const host = createServerHost([file1, file2, file3]);
            const projectService = createProjectService(host);

            projectService.openExternalProject({ projectFileName: "project", options: { moduleResolution: ModuleResolutionKind.NodeJs }, rootFiles: toExternalFiles([file1.path, file2.path]) });
            checkNumberOfProjects(projectService, { externalProjects: 1 });
            checkProjectRootFiles(projectService.externalProjects[0], [file1.path, file2.path]);
            checkProjectActualFiles(projectService.externalProjects[0], [file1.path, file2.path]);

            projectService.openExternalProject({ projectFileName: "project", options: { moduleResolution: ModuleResolutionKind.Classic }, rootFiles: toExternalFiles([file1.path, file2.path]) });
            checkNumberOfProjects(projectService, { externalProjects: 1 });
            checkProjectRootFiles(projectService.externalProjects[0], [file1.path, file2.path]);
            checkProjectActualFiles(projectService.externalProjects[0], [file1.path, file2.path, file3.path]);
        });

        it("regression test for crash in acquireOrUpdateDocument", () => {
            const tsFile = {
                fileName: "/a/b/file1.ts",
                path: "/a/b/file1.ts",
                content: ""
            };
            const jsFile = {
                path: "/a/b/file1.js",
                content: "var x = 10;",
                fileName: "/a/b/file1.js",
                scriptKind: "JS" as "JS"
            };

            const host = createServerHost([]);
            const projectService = createProjectService(host);
            projectService.applyChangesInOpenFiles([tsFile], [], []);
            const projs = projectService.synchronizeProjectList([]);
            projectService.findProject(projs[0].info!.projectName)!.getLanguageService().getNavigationBarItems(tsFile.fileName);
            projectService.synchronizeProjectList([projs[0].info!]);
            projectService.applyChangesInOpenFiles([jsFile], [], []);
        });

        it("config file is deleted", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: "let x = 1;"
            };
            const file2 = {
                path: "/a/b/f2.ts",
                content: "let y = 2;"
            };
            const config = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ compilerOptions: {} })
            };
            const host = createServerHost([file1, file2, config]);
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [file1.path, file2.path, config.path]);

            projectService.openClientFile(file2.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [file1.path, file2.path, config.path]);

            host.reloadFS([file1, file2]);
            host.checkTimeoutQueueLengthAndRun(1);
            checkNumberOfProjects(projectService, { inferredProjects: 2 });
            checkProjectActualFiles(projectService.inferredProjects[0], [file1.path]);
            checkProjectActualFiles(projectService.inferredProjects[1], [file2.path]);
        });

        it("loading files with correct priority", () => {
            const f1 = {
                path: "/a/main.ts",
                content: "let x = 1"
            };
            const f2 = {
                path: "/a/main.js",
                content: "var y = 1"
            };
            const config = {
                path: "/a/tsconfig.json",
                content: JSON.stringify({
                    compilerOptions: { allowJs: true }
                })
            };
            const host = createServerHost([f1, f2, config]);
            const projectService = createProjectService(host);
            projectService.setHostConfiguration({
                extraFileExtensions: [
                    { extension: ".js", isMixedContent: false },
                    { extension: ".html", isMixedContent: true }
                ]
            });
            projectService.openClientFile(f1.path);
            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [f1.path, config.path]);

            // Should close configured project with next file open
            projectService.closeClientFile(f1.path);

            projectService.openClientFile(f2.path);
            projectService.checkNumberOfProjects({ inferredProjects: 1 });
            assert.isUndefined(projectService.configuredProjects.get(config.path));
            checkProjectActualFiles(projectService.inferredProjects[0], [f2.path]);
        });

        it("tsconfig script block support", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: ` `
            };
            const file2 = {
                path: "/a/b/f2.html",
                content: `var hello = "hello";`
            };
            const config = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ compilerOptions: { allowJs: true } })
            };
            const host = createServerHost([file1, file2, config]);
            const session = createSession(host);
            openFilesForSession([file1], session);
            const projectService = session.getProjectService();

            // HTML file will not be included in any projects yet
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            const configuredProj = configuredProjectAt(projectService, 0);
            checkProjectActualFiles(configuredProj, [file1.path, config.path]);

            // Specify .html extension as mixed content
            const extraFileExtensions = [{ extension: ".html", scriptKind: ScriptKind.JS, isMixedContent: true }];
            const configureHostRequest = makeSessionRequest<protocol.ConfigureRequestArguments>(CommandNames.Configure, { extraFileExtensions });
            session.executeCommand(configureHostRequest);

            // The configured project should now be updated to include html file
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            assert.strictEqual(configuredProjectAt(projectService, 0), configuredProj, "Same configured project should be updated");
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [file1.path, file2.path, config.path]);

            // Open HTML file
            projectService.applyChangesInOpenFiles(
                /*openFiles*/[{ fileName: file2.path, hasMixedContent: true, scriptKind: ScriptKind.JS, content: `var hello = "hello";` }],
                /*changedFiles*/ undefined,
                /*closedFiles*/ undefined);

            // Now HTML file is included in the project
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [file1.path, file2.path, config.path]);

            // Check identifiers defined in HTML content are available in .ts file
            const project = configuredProjectAt(projectService, 0);
            let completions = project.getLanguageService().getCompletionsAtPosition(file1.path, 1, emptyOptions);
            assert(completions && completions.entries[0].name === "hello", `expected entry hello to be in completion list`);

            // Close HTML file
            projectService.applyChangesInOpenFiles(
                /*openFiles*/ undefined,
                /*changedFiles*/ undefined,
                /*closedFiles*/[file2.path]);

            // HTML file is still included in project
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [file1.path, file2.path, config.path]);

            // Check identifiers defined in HTML content are not available in .ts file
            completions = project.getLanguageService().getCompletionsAtPosition(file1.path, 5, emptyOptions);
            assert(completions && completions.entries[0].name !== "hello", `unexpected hello entry in completion list`);
        });

        it("no tsconfig script block diagnostic errors", () => {

            //  #1. Ensure no diagnostic errors when allowJs is true
            const file1 = {
                path: "/a/b/f1.ts",
                content: ` `
            };
            const file2 = {
                path: "/a/b/f2.html",
                content: `var hello = "hello";`
            };
            const config1 = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ compilerOptions: { allowJs: true } })
            };

            let host = createServerHost([file1, file2, config1, libFile], { executingFilePath: combinePaths(getDirectoryPath(libFile.path), "tsc.js") });
            let session = createSession(host);

            // Specify .html extension as mixed content in a configure host request
            const extraFileExtensions = [{ extension: ".html", scriptKind: ScriptKind.JS, isMixedContent: true }];
            const configureHostRequest = makeSessionRequest<protocol.ConfigureRequestArguments>(CommandNames.Configure, { extraFileExtensions });
            session.executeCommand(configureHostRequest);

            openFilesForSession([file1], session);
            let projectService = session.getProjectService();

            checkNumberOfProjects(projectService, { configuredProjects: 1 });

            let diagnostics = configuredProjectAt(projectService, 0).getLanguageService().getCompilerOptionsDiagnostics();
            assert.deepEqual(diagnostics, []);

            //  #2. Ensure no errors when allowJs is false
            const config2 = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ compilerOptions: { allowJs: false } })
            };

            host = createServerHost([file1, file2, config2, libFile], { executingFilePath: combinePaths(getDirectoryPath(libFile.path), "tsc.js") });
            session = createSession(host);

            session.executeCommand(configureHostRequest);

            openFilesForSession([file1], session);
            projectService = session.getProjectService();

            checkNumberOfProjects(projectService, { configuredProjects: 1 });

            diagnostics = configuredProjectAt(projectService, 0).getLanguageService().getCompilerOptionsDiagnostics();
            assert.deepEqual(diagnostics, []);

            //  #3. Ensure no errors when compiler options aren't specified
            const config3 = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({})
            };

            host = createServerHost([file1, file2, config3, libFile], { executingFilePath: combinePaths(getDirectoryPath(libFile.path), "tsc.js") });
            session = createSession(host);

            session.executeCommand(configureHostRequest);

            openFilesForSession([file1], session);
            projectService = session.getProjectService();

            checkNumberOfProjects(projectService, { configuredProjects: 1 });

            diagnostics = configuredProjectAt(projectService, 0).getLanguageService().getCompilerOptionsDiagnostics();
            assert.deepEqual(diagnostics, []);

            //  #4. Ensure no errors when files are explicitly specified in tsconfig
            const config4 = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ compilerOptions: { allowJs: true }, files: [file1.path, file2.path] })
            };

            host = createServerHost([file1, file2, config4, libFile], { executingFilePath: combinePaths(getDirectoryPath(libFile.path), "tsc.js") });
            session = createSession(host);

            session.executeCommand(configureHostRequest);

            openFilesForSession([file1], session);
            projectService = session.getProjectService();

            checkNumberOfProjects(projectService, { configuredProjects: 1 });

            diagnostics = configuredProjectAt(projectService, 0).getLanguageService().getCompilerOptionsDiagnostics();
            assert.deepEqual(diagnostics, []);

            //  #4. Ensure no errors when files are explicitly excluded in tsconfig
            const config5 = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ compilerOptions: { allowJs: true }, exclude: [file2.path] })
            };

            host = createServerHost([file1, file2, config5, libFile], { executingFilePath: combinePaths(getDirectoryPath(libFile.path), "tsc.js") });
            session = createSession(host);

            session.executeCommand(configureHostRequest);

            openFilesForSession([file1], session);
            projectService = session.getProjectService();

            checkNumberOfProjects(projectService, { configuredProjects: 1 });

            diagnostics = configuredProjectAt(projectService, 0).getLanguageService().getCompilerOptionsDiagnostics();
            assert.deepEqual(diagnostics, []);
        });

        it("project structure update is deferred if files are not added\removed", () => {
            const file1 = {
                path: "/a/b/f1.ts",
                content: `import {x} from "./f2"`
            };
            const file2 = {
                path: "/a/b/f2.ts",
                content: "export let x = 1"
            };
            const host = createServerHost([file1, file2]);
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);
            projectService.openClientFile(file2.path);

            checkNumberOfProjects(projectService, { inferredProjects: 1 });
            projectService.applyChangesInOpenFiles(
                /*openFiles*/ undefined,
                /*changedFiles*/[{ fileName: file1.path, changes: [{ span: createTextSpan(0, file1.path.length), newText: "let y = 1" }] }],
                /*closedFiles*/ undefined);

            checkNumberOfProjects(projectService, { inferredProjects: 1 });
            projectService.ensureInferredProjectsUpToDate_TestOnly();
            checkNumberOfProjects(projectService, { inferredProjects: 2 });
        });

        it("files with mixed content are handled correctly", () => {
            const file1 = {
                path: "/a/b/f1.html",
                content: `<html><script language="javascript">var x = 1;</></html>`
            };
            const host = createServerHost([file1]);
            const projectService = createProjectService(host);
            const projectFileName = "projectFileName";
            projectService.openExternalProject({ projectFileName, options: {}, rootFiles: [{ fileName: file1.path, scriptKind: ScriptKind.JS, hasMixedContent: true }] });

            checkNumberOfProjects(projectService, { externalProjects: 1 });
            checkWatchedFiles(host, [libFile.path]); // watching the "missing" lib file

            const project = projectService.externalProjects[0];

            const scriptInfo = project.getScriptInfo(file1.path)!;
            const snap = scriptInfo.getSnapshot();
            const actualText = getSnapshotText(snap);
            assert.equal(actualText, "", `expected content to be empty string, got "${actualText}"`);

            projectService.openClientFile(file1.path, `var x = 1;`);
            project.updateGraph();

            const quickInfo = project.getLanguageService().getQuickInfoAtPosition(file1.path, 4)!;
            assert.equal(quickInfo.kind, ScriptElementKind.variableElement);

            projectService.closeClientFile(file1.path);

            const scriptInfo2 = project.getScriptInfo(file1.path)!;
            const actualText2 = getSnapshotText(scriptInfo2.getSnapshot());
            assert.equal(actualText2, "", `expected content to be empty string, got "${actualText2}"`);
        });

        it("project settings for inferred projects", () => {
            const file1 = {
                path: "/a/b/app.ts",
                content: `import {x} from "mod"`
            };
            const modFile = {
                path: "/a/mod.ts",
                content: "export let x: number"
            };
            const host = createServerHost([file1, modFile]);
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);
            projectService.openClientFile(modFile.path);

            checkNumberOfProjects(projectService, { inferredProjects: 2 });
            const inferredProjects = projectService.inferredProjects.slice();
            checkProjectActualFiles(inferredProjects[0], [file1.path]);
            checkProjectActualFiles(inferredProjects[1], [modFile.path]);

            projectService.setCompilerOptionsForInferredProjects({ moduleResolution: ModuleResolutionKind.Classic });
            host.checkTimeoutQueueLengthAndRun(3);
            checkNumberOfProjects(projectService, { inferredProjects: 2 });
            assert.strictEqual(projectService.inferredProjects[0], inferredProjects[0]);
            assert.strictEqual(projectService.inferredProjects[1], inferredProjects[1]);
            checkProjectActualFiles(inferredProjects[0], [file1.path, modFile.path]);
            assert.isTrue(inferredProjects[1].isOrphan());
        });

        it("syntax tree cache handles changes in project settings", () => {
            const file1 = {
                path: "/a/b/app.ts",
                content: "{x: 1}"
            };
            const host = createServerHost([file1]);
            const projectService = createProjectService(host, { useSingleInferredProject: true });
            projectService.setCompilerOptionsForInferredProjects({ target: ScriptTarget.ES5, allowJs: false });
            projectService.openClientFile(file1.path);
            projectService.inferredProjects[0].getLanguageService(/*ensureSynchronized*/ false).getOutliningSpans(file1.path);
            projectService.setCompilerOptionsForInferredProjects({ target: ScriptTarget.ES5, allowJs: true });
            projectService.getScriptInfo(file1.path)!.editContent(0, 0, " ");
            projectService.inferredProjects[0].getLanguageService(/*ensureSynchronized*/ false).getOutliningSpans(file1.path);
            projectService.closeClientFile(file1.path);
        });

        it("File in multiple projects at opened and closed correctly", () => {
            const file1 = {
                path: "/a/b/app.ts",
                content: "let x = 1;"
            };
            const file2 = {
                path: "/a/c/f.ts",
                content: `/// <reference path="../b/app.ts"/>`
            };
            const tsconfig1 = {
                path: "/a/c/tsconfig.json",
                content: "{}"
            };
            const tsconfig2 = {
                path: "/a/b/tsconfig.json",
                content: "{}"
            };
            const host = createServerHost([file1, file2, tsconfig1, tsconfig2]);
            const projectService = createProjectService(host);

            projectService.openClientFile(file2.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            const project1 = projectService.configuredProjects.get(tsconfig1.path)!;
            assert.isTrue(project1.hasOpenRef(), "Has open ref count in project1 - 1"); // file2
            assert.equal(project1.getScriptInfo(file2.path)!.containingProjects.length, 1, "containing projects count");
            assert.isFalse(project1.isClosed());

            projectService.openClientFile(file1.path);
            checkNumberOfProjects(projectService, { configuredProjects: 2 });
            assert.isTrue(project1.hasOpenRef(), "Has open ref count in project1 - 2"); // file2
            assert.strictEqual(projectService.configuredProjects.get(tsconfig1.path), project1);
            assert.isFalse(project1.isClosed());

            const project2 = projectService.configuredProjects.get(tsconfig2.path)!;
            assert.isTrue(project2.hasOpenRef(), "Has open ref count in project2 - 2"); // file1
            assert.isFalse(project2.isClosed());

            assert.equal(project1.getScriptInfo(file1.path)!.containingProjects.length, 2, `${file1.path} containing projects count`);
            assert.equal(project1.getScriptInfo(file2.path)!.containingProjects.length, 1, `${file2.path} containing projects count`);

            projectService.closeClientFile(file2.path);
            checkNumberOfProjects(projectService, { configuredProjects: 2 });
            assert.isFalse(project1.hasOpenRef(), "Has open ref count in project1 - 3"); // No files
            assert.isTrue(project2.hasOpenRef(), "Has open ref count in project2 - 3"); // file1
            assert.strictEqual(projectService.configuredProjects.get(tsconfig1.path), project1);
            assert.strictEqual(projectService.configuredProjects.get(tsconfig2.path), project2);
            assert.isFalse(project1.isClosed());
            assert.isFalse(project2.isClosed());

            projectService.closeClientFile(file1.path);
            checkNumberOfProjects(projectService, { configuredProjects: 2 });
            assert.isFalse(project1.hasOpenRef(), "Has open ref count in project1 - 4"); // No files
            assert.isFalse(project2.hasOpenRef(), "Has open ref count in project2 - 4"); // No files
            assert.strictEqual(projectService.configuredProjects.get(tsconfig1.path), project1);
            assert.strictEqual(projectService.configuredProjects.get(tsconfig2.path), project2);
            assert.isFalse(project1.isClosed());
            assert.isFalse(project2.isClosed());

            projectService.openClientFile(file2.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            assert.strictEqual(projectService.configuredProjects.get(tsconfig1.path), project1);
            assert.isUndefined(projectService.configuredProjects.get(tsconfig2.path));
            assert.isTrue(project1.hasOpenRef(), "Has open ref count in project1 - 5"); // file2
            assert.isFalse(project1.isClosed());
            assert.isTrue(project2.isClosed());
        });

        it("Open ref of configured project when open file gets added to the project as part of configured file update", () => {
            const file1: File = {
                path: "/a/b/src/file1.ts",
                content: "let x = 1;"
            };
            const file2: File = {
                path: "/a/b/src/file2.ts",
                content: "let y = 1;"
            };
            const file3: File = {
                path: "/a/b/file3.ts",
                content: "let z = 1;"
            };
            const file4: File = {
                path: "/a/file4.ts",
                content: "let z = 1;"
            };
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ files: ["src/file1.ts", "file3.ts"] })
            };

            const files = [file1, file2, file3, file4];
            const host = createServerHost(files.concat(configFile));
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);
            projectService.openClientFile(file2.path);
            projectService.openClientFile(file3.path);
            projectService.openClientFile(file4.path);

            const infos = files.map(file => projectService.getScriptInfoForPath(file.path as Path)!);
            checkOpenFiles(projectService, files);
            checkNumberOfProjects(projectService, { configuredProjects: 1, inferredProjects: 2 });
            const configProject1 = projectService.configuredProjects.get(configFile.path)!;
            assert.isTrue(configProject1.hasOpenRef()); // file1 and file3
            checkProjectActualFiles(configProject1, [file1.path, file3.path, configFile.path]);
            const inferredProject1 = projectService.inferredProjects[0];
            checkProjectActualFiles(inferredProject1, [file2.path]);
            const inferredProject2 = projectService.inferredProjects[1];
            checkProjectActualFiles(inferredProject2, [file4.path]);

            configFile.content = "{}";
            host.reloadFS(files.concat(configFile));
            host.runQueuedTimeoutCallbacks();

            verifyScriptInfos();
            checkOpenFiles(projectService, files);
            verifyConfiguredProjectStateAfterUpdate(/*hasOpenRef*/ true, 2); // file1, file2, file3
            assert.isTrue(projectService.inferredProjects[0].isOrphan());
            const inferredProject3 = projectService.inferredProjects[1];
            checkProjectActualFiles(inferredProject3, [file4.path]);
            assert.strictEqual(inferredProject3, inferredProject2);

            projectService.closeClientFile(file1.path);
            projectService.closeClientFile(file2.path);
            projectService.closeClientFile(file4.path);

            verifyScriptInfos();
            checkOpenFiles(projectService, [file3]);
            verifyConfiguredProjectStateAfterUpdate(/*hasOpenRef*/ true, 2); // file3
            assert.isTrue(projectService.inferredProjects[0].isOrphan());
            assert.isTrue(projectService.inferredProjects[1].isOrphan());

            projectService.openClientFile(file4.path);
            verifyScriptInfos();
            checkOpenFiles(projectService, [file3, file4]);
            verifyConfiguredProjectStateAfterUpdate(/*hasOpenRef*/ true, 1); // file3
            const inferredProject4 = projectService.inferredProjects[0];
            checkProjectActualFiles(inferredProject4, [file4.path]);

            projectService.closeClientFile(file3.path);
            verifyScriptInfos();
            checkOpenFiles(projectService, [file4]);
            verifyConfiguredProjectStateAfterUpdate(/*hasOpenRef*/ false, 1); // No open files
            const inferredProject5 = projectService.inferredProjects[0];
            checkProjectActualFiles(inferredProject4, [file4.path]);
            assert.strictEqual(inferredProject5, inferredProject4);

            const file5: File = {
                path: "/file5.ts",
                content: "let zz = 1;"
            };
            host.reloadFS(files.concat(configFile, file5));
            projectService.openClientFile(file5.path);
            verifyScriptInfosAreUndefined([file1, file2, file3]);
            assert.strictEqual(projectService.getScriptInfoForPath(file4.path as Path), find(infos, info => info.path === file4.path));
            assert.isDefined(projectService.getScriptInfoForPath(file5.path as Path));
            checkOpenFiles(projectService, [file4, file5]);
            checkNumberOfProjects(projectService, { inferredProjects: 2 });
            checkProjectActualFiles(projectService.inferredProjects[0], [file4.path]);
            checkProjectActualFiles(projectService.inferredProjects[1], [file5.path]);

            function verifyScriptInfos() {
                infos.forEach(info => assert.strictEqual(projectService.getScriptInfoForPath(info.path), info));
            }

            function verifyScriptInfosAreUndefined(files: File[]) {
                for (const file of files) {
                    assert.isUndefined(projectService.getScriptInfoForPath(file.path as Path));
                }
            }

            function verifyConfiguredProjectStateAfterUpdate(hasOpenRef: boolean, inferredProjects: number) {
                checkNumberOfProjects(projectService, { configuredProjects: 1, inferredProjects });
                const configProject2 = projectService.configuredProjects.get(configFile.path)!;
                assert.strictEqual(configProject2, configProject1);
                checkProjectActualFiles(configProject2, [file1.path, file2.path, file3.path, configFile.path]);
                assert.equal(configProject2.hasOpenRef(), hasOpenRef);
            }
        });

        it("Open ref of configured project when open file gets added to the project as part of configured file update buts its open file references are all closed when the update happens", () => {
            const file1: File = {
                path: "/a/b/src/file1.ts",
                content: "let x = 1;"
            };
            const file2: File = {
                path: "/a/b/src/file2.ts",
                content: "let y = 1;"
            };
            const file3: File = {
                path: "/a/b/file3.ts",
                content: "let z = 1;"
            };
            const file4: File = {
                path: "/a/file4.ts",
                content: "let z = 1;"
            };
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ files: ["src/file1.ts", "file3.ts"] })
            };

            const files = [file1, file2, file3];
            const hostFiles = files.concat(file4, configFile);
            const host = createServerHost(hostFiles);
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);
            projectService.openClientFile(file2.path);
            projectService.openClientFile(file3.path);

            checkNumberOfProjects(projectService, { configuredProjects: 1, inferredProjects: 1 });
            const configuredProject = projectService.configuredProjects.get(configFile.path)!;
            assert.isTrue(configuredProject.hasOpenRef()); // file1 and file3
            checkProjectActualFiles(configuredProject, [file1.path, file3.path, configFile.path]);
            const inferredProject1 = projectService.inferredProjects[0];
            checkProjectActualFiles(inferredProject1, [file2.path]);

            projectService.closeClientFile(file1.path);
            projectService.closeClientFile(file3.path);
            assert.isFalse(configuredProject.hasOpenRef()); // No files

            configFile.content = "{}";
            host.reloadFS(files.concat(configFile));
            // Time out is not yet run so there is project update pending
            assert.isTrue(configuredProject.hasOpenRef()); // Pending update and file2 might get into the project

            projectService.openClientFile(file4.path);

            checkNumberOfProjects(projectService, { configuredProjects: 1, inferredProjects: 2 });
            assert.strictEqual(projectService.configuredProjects.get(configFile.path), configuredProject);
            assert.isTrue(configuredProject.hasOpenRef()); // Pending update and F2 might get into the project
            assert.strictEqual(projectService.inferredProjects[0], inferredProject1);
            const inferredProject2 = projectService.inferredProjects[1];
            checkProjectActualFiles(inferredProject2, [file4.path]);

            host.runQueuedTimeoutCallbacks();
            checkNumberOfProjects(projectService, { configuredProjects: 1, inferredProjects: 2 });
            assert.strictEqual(projectService.configuredProjects.get(configFile.path), configuredProject);
            assert.isTrue(configuredProject.hasOpenRef()); // file2
            checkProjectActualFiles(configuredProject, [file1.path, file2.path, file3.path, configFile.path]);
            assert.strictEqual(projectService.inferredProjects[0], inferredProject1);
            assert.isTrue(inferredProject1.isOrphan());
            assert.strictEqual(projectService.inferredProjects[1], inferredProject2);
            checkProjectActualFiles(inferredProject2, [file4.path]);
        });

        it("language service disabled state is updated in external projects", () => {
            const f1 = {
                path: "/a/app.js",
                content: "var x = 1"
            };
            const f2 = {
                path: "/a/largefile.js",
                content: ""
            };
            const host = createServerHost([f1, f2]);
            const originalGetFileSize = host.getFileSize;
            host.getFileSize = (filePath: string) =>
                filePath === f2.path ? server.maxProgramSizeForNonTsFiles + 1 : originalGetFileSize.call(host, filePath);

            const service = createProjectService(host);
            const projectFileName = "/a/proj.csproj";

            service.openExternalProject({
                projectFileName,
                rootFiles: toExternalFiles([f1.path, f2.path]),
                options: {}
            });
            service.checkNumberOfProjects({ externalProjects: 1 });
            assert.isFalse(service.externalProjects[0].languageServiceEnabled, "language service should be disabled - 1");

            service.openExternalProject({
                projectFileName,
                rootFiles: toExternalFiles([f1.path]),
                options: {}
            });
            service.checkNumberOfProjects({ externalProjects: 1 });
            assert.isTrue(service.externalProjects[0].languageServiceEnabled, "language service should be enabled");

            service.openExternalProject({
                projectFileName,
                rootFiles: toExternalFiles([f1.path, f2.path]),
                options: {}
            });
            service.checkNumberOfProjects({ externalProjects: 1 });
            assert.isFalse(service.externalProjects[0].languageServiceEnabled, "language service should be disabled - 2");
        });

        it("files are properly detached when language service is disabled", () => {
            const f1 = {
                path: "/a/app.js",
                content: "var x = 1"
            };
            const f2 = {
                path: "/a/largefile.js",
                content: ""
            };
            const f3 = {
                path: "/a/lib.js",
                content: "var x = 1"
            };
            const config = {
                path: "/a/tsconfig.json",
                content: JSON.stringify({ compilerOptions: { allowJs: true } })
            };
            const host = createServerHost([f1, f2, f3, config]);
            const originalGetFileSize = host.getFileSize;
            host.getFileSize = (filePath: string) =>
                filePath === f2.path ? server.maxProgramSizeForNonTsFiles + 1 : originalGetFileSize.call(host, filePath);

            const projectService = createProjectService(host);
            projectService.openClientFile(f1.path);
            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            const project = projectService.configuredProjects.get(config.path)!;
            assert.isTrue(project.hasOpenRef()); // f1
            assert.isFalse(project.isClosed());

            projectService.closeClientFile(f1.path);
            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            assert.strictEqual(projectService.configuredProjects.get(config.path), project);
            assert.isFalse(project.hasOpenRef()); // No files
            assert.isFalse(project.isClosed());

            for (const f of [f1, f2, f3]) {
                // All the script infos should be present and contain the project since it is still alive.
                const scriptInfo = projectService.getScriptInfoForNormalizedPath(server.toNormalizedPath(f.path))!;
                assert.equal(scriptInfo.containingProjects.length, 1, `expect 1 containing projects for '${f.path}'`);
                assert.equal(scriptInfo.containingProjects[0], project, `expect configured project to be the only containing project for '${f.path}'`);
            }

            const f4 = {
                path: "/aa.js",
                content: "var x = 1"
            };
            host.reloadFS([f1, f2, f3, config, f4]);
            projectService.openClientFile(f4.path);
            projectService.checkNumberOfProjects({ inferredProjects: 1 });
            assert.isFalse(project.hasOpenRef()); // No files
            assert.isTrue(project.isClosed());

            for (const f of [f1, f2, f3]) {
                // All the script infos should not be present since the project is closed and orphan script infos are collected
                assert.isUndefined(projectService.getScriptInfoForNormalizedPath(server.toNormalizedPath(f.path)));
            }
        });

        it("language service disabled events are triggered", () => {
            const f1 = {
                path: "/a/app.js",
                content: "let x = 1;"
            };
            const f2 = {
                path: "/a/largefile.js",
                content: ""
            };
            const config = {
                path: "/a/jsconfig.json",
                content: "{}"
            };
            const configWithExclude = {
                path: config.path,
                content: JSON.stringify({ exclude: ["largefile.js"] })
            };
            const host = createServerHost([f1, f2, config]);
            const originalGetFileSize = host.getFileSize;
            host.getFileSize = (filePath: string) =>
                filePath === f2.path ? server.maxProgramSizeForNonTsFiles + 1 : originalGetFileSize.call(host, filePath);

            let lastEvent!: server.ProjectLanguageServiceStateEvent;
            const session = createSession(host, {
                canUseEvents: true,
                eventHandler: e => {
                    if (e.eventName === server.ConfigFileDiagEvent || e.eventName === server.ProjectsUpdatedInBackgroundEvent || e.eventName === server.ProjectInfoTelemetryEvent || e.eventName === server.OpenFileInfoTelemetryEvent) {
                        return;
                    }
                    assert.equal(e.eventName, server.ProjectLanguageServiceStateEvent);
                    assert.equal(e.data.project.getProjectName(), config.path, "project name");
                    lastEvent = e;
                }
            });
            session.executeCommand(<protocol.OpenRequest>{
                seq: 0,
                type: "request",
                command: "open",
                arguments: { file: f1.path }
            });
            const projectService = session.getProjectService();
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            const project = configuredProjectAt(projectService, 0);
            assert.isFalse(project.languageServiceEnabled, "Language service enabled");
            assert.isTrue(!!lastEvent, "should receive event");
            assert.equal(lastEvent.data.project, project, "project name");
            assert.equal(lastEvent.data.project.getProjectName(), config.path, "config path");
            assert.isFalse(lastEvent.data.languageServiceEnabled, "Language service state");

            host.reloadFS([f1, f2, configWithExclude]);
            host.checkTimeoutQueueLengthAndRun(2);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            assert.isTrue(project.languageServiceEnabled, "Language service enabled");
            assert.equal(lastEvent.data.project, project, "project");
            assert.isTrue(lastEvent.data.languageServiceEnabled, "Language service state");
        });

        it("syntactic features work even if language service is disabled", () => {
            const f1 = {
                path: "/a/app.js",
                content: "let x =   1;"
            };
            const f2 = {
                path: "/a/largefile.js",
                content: ""
            };
            const config = {
                path: "/a/jsconfig.json",
                content: "{}"
            };
            const host = createServerHost([f1, f2, config]);
            const originalGetFileSize = host.getFileSize;
            host.getFileSize = (filePath: string) =>
                filePath === f2.path ? server.maxProgramSizeForNonTsFiles + 1 : originalGetFileSize.call(host, filePath);
            let lastEvent!: server.ProjectLanguageServiceStateEvent;
            const session = createSession(host, {
                canUseEvents: true,
                eventHandler: e => {
                    if (e.eventName === server.ConfigFileDiagEvent || e.eventName === server.ProjectInfoTelemetryEvent || e.eventName === server.OpenFileInfoTelemetryEvent) {
                        return;
                    }
                    assert.equal(e.eventName, server.ProjectLanguageServiceStateEvent);
                    lastEvent = <server.ProjectLanguageServiceStateEvent>e;
                }
            });
            session.executeCommand(<protocol.OpenRequest>{
                seq: 0,
                type: "request",
                command: "open",
                arguments: { file: f1.path }
            });

            const projectService = session.getProjectService();
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            const project = configuredProjectAt(projectService, 0);
            assert.isFalse(project.languageServiceEnabled, "Language service enabled");
            assert.isTrue(!!lastEvent, "should receive event");
            assert.equal(lastEvent.data.project, project, "project name");
            assert.isFalse(lastEvent.data.languageServiceEnabled, "Language service state");

            const options = projectService.getFormatCodeOptions(f1.path as server.NormalizedPath);
            const edits = project.getLanguageService().getFormattingEditsForDocument(f1.path, options);
            assert.deepEqual(edits, [{ span: createTextSpan(/*start*/ 7, /*length*/ 3), newText: " " }]);
        });

        it("snapshot from different caches are incompatible", () => {
            const f1 = {
                path: "/a/b/app.ts",
                content: "let x = 1;"
            };
            const host = createServerHost([f1]);
            const projectFileName = "/a/b/proj.csproj";
            const projectService = createProjectService(host);
            projectService.openExternalProject({
                projectFileName,
                rootFiles: [toExternalFile(f1.path)],
                options: {}
            });
            projectService.openClientFile(f1.path, "let x = 1;\nlet y = 2;");

            projectService.checkNumberOfProjects({ externalProjects: 1 });
            projectService.externalProjects[0].getLanguageService(/*ensureSynchronized*/ false).getNavigationBarItems(f1.path);
            projectService.closeClientFile(f1.path);

            projectService.openClientFile(f1.path);
            projectService.checkNumberOfProjects({ externalProjects: 1 });
            const navbar = projectService.externalProjects[0].getLanguageService(/*ensureSynchronized*/ false).getNavigationBarItems(f1.path);
            assert.equal(navbar[0].spans[0].length, f1.content.length);
        });

        it("deleting config file opened from the external project works", () => {
            const site = {
                path: "/user/someuser/project/js/site.js",
                content: ""
            };
            const configFile = {
                path: "/user/someuser/project/tsconfig.json",
                content: "{}"
            };
            const projectFileName = "/user/someuser/project/WebApplication6.csproj";
            const host = createServerHost([libFile, site, configFile]);
            const projectService = createProjectService(host);

            const externalProject: protocol.ExternalProject = {
                projectFileName,
                rootFiles: [toExternalFile(site.path), toExternalFile(configFile.path)],
                options: { allowJs: false },
                typeAcquisition: { include: [] }
            };

            projectService.openExternalProjects([externalProject]);

            let knownProjects = projectService.synchronizeProjectList([]);
            checkNumberOfProjects(projectService, { configuredProjects: 1, externalProjects: 0, inferredProjects: 0 });

            const configProject = configuredProjectAt(projectService, 0);
            checkProjectActualFiles(configProject, [libFile.path, configFile.path]);

            const diagnostics = configProject.getAllProjectErrors();
            assert.equal(diagnostics[0].code, Diagnostics.No_inputs_were_found_in_config_file_0_Specified_include_paths_were_1_and_exclude_paths_were_2.code);

            host.reloadFS([libFile, site]);
            host.checkTimeoutQueueLengthAndRun(1);

            knownProjects = projectService.synchronizeProjectList(map(knownProjects, proj => proj.info!)); // TODO: GH#18217 GH#20039
            checkNumberOfProjects(projectService, { configuredProjects: 0, externalProjects: 0, inferredProjects: 0 });

            externalProject.rootFiles.length = 1;
            projectService.openExternalProjects([externalProject]);

            checkNumberOfProjects(projectService, { configuredProjects: 0, externalProjects: 1, inferredProjects: 0 });
            checkProjectActualFiles(projectService.externalProjects[0], [site.path, libFile.path]);
        });

        it("Getting errors from closed script info does not throw exception (because of getting project from orphan script info)", () => {
            const { logger, hasErrorMsg } = createHasErrorMessageLogger();
            const f1 = {
                path: "/a/b/app.ts",
                content: "let x = 1;"
            };
            const config = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ compilerOptions: {} })
            };
            const host = createServerHost([f1, libFile, config]);
            const session = createSession(host, { logger });
            session.executeCommandSeq(<protocol.OpenRequest>{
                command: server.CommandNames.Open,
                arguments: {
                    file: f1.path
                }
            });
            session.executeCommandSeq(<protocol.CloseRequest>{
                command: server.CommandNames.Close,
                arguments: {
                    file: f1.path
                }
            });
            session.executeCommandSeq(<protocol.GeterrRequest>{
                command: server.CommandNames.Geterr,
                arguments: {
                    delay: 0,
                    files: [f1.path]
                }
            });
            assert.isFalse(hasErrorMsg());
        });

        it("Changed module resolution reflected when specifying files list", () => {
            const file1: File = {
                path: "/a/b/file1.ts",
                content: 'import classc from "file2"'
            };
            const file2a: File = {
                path: "/a/file2.ts",
                content: "export classc { method2a() { return 10; } }"
            };
            const file2: File = {
                path: "/a/b/file2.ts",
                content: "export classc { method2() { return 10; } }"
            };
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ files: [file1.path], compilerOptions: { module: "amd" } })
            };
            const files = [file1, file2a, configFile, libFile];
            const host = createServerHost(files);
            const projectService = createProjectService(host);
            projectService.openClientFile(file1.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            const project = projectService.configuredProjects.get(configFile.path)!;
            assert.isDefined(project);
            checkProjectActualFiles(project, map(files, file => file.path));
            checkWatchedFiles(host, mapDefined(files, file => file === file1 ? undefined : file.path));
            checkWatchedDirectories(host, [], /*recursive*/ false);
            const watchedRecursiveDirectories = ["/a/b/node_modules/@types"];
            watchedRecursiveDirectories.push("/a/b");
            checkWatchedDirectories(host, watchedRecursiveDirectories, /*recursive*/ true);

            files.push(file2);
            host.reloadFS(files);
            host.runQueuedTimeoutCallbacks();
            watchedRecursiveDirectories.pop();
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            assert.strictEqual(projectService.configuredProjects.get(configFile.path), project);
            checkProjectActualFiles(project, mapDefined(files, file => file === file2a ? undefined : file.path));
            checkWatchedFiles(host, mapDefined(files, file => file === file1 ? undefined : file.path));
            checkWatchedDirectories(host, [], /*recursive*/ false);
            checkWatchedDirectories(host, watchedRecursiveDirectories, /*recursive*/ true);

            // On next file open the files file2a should be closed and not watched any more
            projectService.openClientFile(file2.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            assert.strictEqual(projectService.configuredProjects.get(configFile.path), project);
            checkProjectActualFiles(project, mapDefined(files, file => file === file2a ? undefined : file.path));
            checkWatchedFiles(host, [libFile.path, configFile.path]);
            checkWatchedDirectories(host, [], /*recursive*/ false);
            checkWatchedDirectories(host, watchedRecursiveDirectories, /*recursive*/ true);

        });

        it("Failed lookup locations uses parent most node_modules directory", () => {
            const root = "/user/username/rootfolder";
            const file1: File = {
                path: "/a/b/src/file1.ts",
                content: 'import { classc } from "module1"'
            };
            const module1: File = {
                path: "/a/b/node_modules/module1/index.d.ts",
                content: `import { class2 } from "module2";
                          export classc { method2a(): class2; }`
            };
            const module2: File = {
                path: "/a/b/node_modules/module2/index.d.ts",
                content: "export class2 { method2() { return 10; } }"
            };
            const module3: File = {
                path: "/a/b/node_modules/module/node_modules/module3/index.d.ts",
                content: "export class3 { method2() { return 10; } }"
            };
            const configFile: File = {
                path: "/a/b/src/tsconfig.json",
                content: JSON.stringify({ files: ["file1.ts"] })
            };
            const nonLibFiles = [file1, module1, module2, module3, configFile];
            nonLibFiles.forEach(f => f.path = root + f.path);
            const files = nonLibFiles.concat(libFile);
            const host = createServerHost(files);
            const projectService = createProjectService(host);
            projectService.openClientFile(file1.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            const project = projectService.configuredProjects.get(configFile.path)!;
            assert.isDefined(project);
            checkProjectActualFiles(project, [file1.path, libFile.path, module1.path, module2.path, configFile.path]);
            checkWatchedFiles(host, [libFile.path, module1.path, module2.path, configFile.path]);
            checkWatchedDirectories(host, [], /*recursive*/ false);
            const watchedRecursiveDirectories = getTypeRootsFromLocation(root + "/a/b/src");
            watchedRecursiveDirectories.push(`${root}/a/b/src`, `${root}/a/b/node_modules`);
            checkWatchedDirectories(host, watchedRecursiveDirectories, /*recursive*/ true);
        });

        it("Properly handle Windows-style outDir", () => {
            const configFile: File = {
                path: "C:\\a\\tsconfig.json",
                content: JSON.stringify({
                    compilerOptions: {
                        outDir: `C:\\a\\b`
                    },
                    include: ["*.ts"]
                })
            };
            const file1: File = {
                path: "C:\\a\\f1.ts",
                content: "let x = 1;"
            };

            const host = createServerHost([file1, configFile], { useWindowsStylePaths: true });
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            const project = configuredProjectAt(projectService, 0);
            checkProjectActualFiles(project, [normalizePath(file1.path), normalizePath(configFile.path)]);
            const options = project.getCompilerOptions();
            assert.equal(options.outDir, "C:/a/b", "");
        });

        it("dynamic file without external project", () => {
            const file: File = {
                path: "^walkThroughSnippet:/Users/UserName/projects/someProject/out/someFile#1.js",
                content: "var x = 10;"
            };
            const host = createServerHost([libFile], { useCaseSensitiveFileNames: true });
            const projectService = createProjectService(host);
            projectService.setCompilerOptionsForInferredProjects({
                module: ModuleKind.CommonJS,
                allowJs: true,
                allowSyntheticDefaultImports: true,
                allowNonTsExtensions: true
            });
            projectService.openClientFile(file.path, "var x = 10;");

            projectService.checkNumberOfProjects({ inferredProjects: 1 });
            const project = projectService.inferredProjects[0];
            checkProjectRootFiles(project, [file.path]);
            checkProjectActualFiles(project, [file.path, libFile.path]);

            assert.strictEqual(projectService.ensureDefaultProjectForFile(server.toNormalizedPath(file.path)), project);
            const indexOfX = file.content.indexOf("x");
            assert.deepEqual(project.getLanguageService(/*ensureSynchronized*/ true).getQuickInfoAtPosition(file.path, indexOfX), {
                kind: ScriptElementKind.variableElement,
                kindModifiers: "",
                textSpan: { start: indexOfX, length: 1 },
                displayParts: [
                    { text: "var", kind: "keyword" },
                    { text: " ", kind: "space" },
                    { text: "x", kind: "localName" },
                    { text: ":", kind: "punctuation" },
                    { text: " ", kind: "space" },
                    { text: "number", kind: "keyword" }
                ],
                documentation: [],
                tags: []
            });
        });

        it("files opened, closed affecting multiple projects", () => {
            const file: File = {
                path: "/a/b/projects/config/file.ts",
                content: `import {a} from "../files/file1"; export let b = a;`
            };
            const config: File = {
                path: "/a/b/projects/config/tsconfig.json",
                content: ""
            };
            const filesFile1: File = {
                path: "/a/b/projects/files/file1.ts",
                content: "export let a = 10;"
            };
            const filesFile2: File = {
                path: "/a/b/projects/files/file2.ts",
                content: "export let aa = 10;"
            };

            const files = [config, file, filesFile1, filesFile2, libFile];
            const host = createServerHost(files);
            const session = createSession(host);
            // Create configured project
            session.executeCommandSeq<protocol.OpenRequest>({
                command: protocol.CommandTypes.Open,
                arguments: {
                    file: file.path
                }
            });

            const projectService = session.getProjectService();
            const configuredProject = projectService.configuredProjects.get(config.path)!;
            verifyConfiguredProject();

            // open files/file1 = should not create another project
            session.executeCommandSeq<protocol.OpenRequest>({
                command: protocol.CommandTypes.Open,
                arguments: {
                    file: filesFile1.path
                }
            });
            verifyConfiguredProject();

            // Close the file = should still have project
            session.executeCommandSeq<protocol.CloseRequest>({
                command: protocol.CommandTypes.Close,
                arguments: {
                    file: file.path
                }
            });
            verifyConfiguredProject();

            // Open files/file2 - should create inferred project and close configured project
            session.executeCommandSeq<protocol.OpenRequest>({
                command: protocol.CommandTypes.Open,
                arguments: {
                    file: filesFile2.path
                }
            });
            checkNumberOfProjects(projectService, { inferredProjects: 1 });
            checkProjectActualFiles(projectService.inferredProjects[0], [libFile.path, filesFile2.path]);

            // Actions on file1 would result in assert
            session.executeCommandSeq<protocol.OccurrencesRequest>({
                command: protocol.CommandTypes.Occurrences,
                arguments: {
                    file: filesFile1.path,
                    line: 1,
                    offset: filesFile1.content.indexOf("a")
                }
            });

            function verifyConfiguredProject() {
                checkNumberOfProjects(projectService, { configuredProjects: 1 });
                checkProjectActualFiles(configuredProject, [file.path, filesFile1.path, libFile.path, config.path]);
            }
        });

        it("requests are done on file on pendingReload but has svc for previous version", () => {
            const projectLocation = "/user/username/projects/project";
            const file1: File = {
                path: `${projectLocation}/src/file1.ts`,
                content: `import { y } from "./file2"; let x = 10;`
            };
            const file2: File = {
                path: `${projectLocation}/src/file2.ts`,
                content: "export let y = 10;"
            };
            const config: File = {
                path: `${projectLocation}/tsconfig.json`,
                content: "{}"
            };
            const files = [file1, file2, libFile, config];
            const host = createServerHost(files);
            const session = createSession(host);
            session.executeCommandSeq<protocol.OpenRequest>({
                command: protocol.CommandTypes.Open,
                arguments: { file: file2.path, fileContent: file2.content }
            });
            session.executeCommandSeq<protocol.OpenRequest>({
                command: protocol.CommandTypes.Open,
                arguments: { file: file1.path }
            });
            session.executeCommandSeq<protocol.CloseRequest>({
                command: protocol.CommandTypes.Close,
                arguments: { file: file2.path }
            });

            file2.content += "export let z = 10;";
            host.reloadFS(files);
            // Do not let the timeout runs, before executing command
            const startOffset = file2.content.indexOf("y") + 1;
            session.executeCommandSeq<protocol.GetApplicableRefactorsRequest>({
                command: protocol.CommandTypes.GetApplicableRefactors,
                arguments: { file: file2.path, startLine: 1, startOffset, endLine: 1, endOffset: startOffset + 1 }
            });

        });

        it("includes deferred files in the project context", () => {
            const file1 = {
                path: "/a.deferred",
                content: "const a = 1;"
            };
            // Deferred extensions should not affect JS files.
            const file2 = {
                path: "/b.js",
                content: "const b = 1;"
            };
            const tsconfig = {
                path: "/tsconfig.json",
                content: ""
            };

            const host = createServerHost([file1, file2, tsconfig]);
            const session = createSession(host);
            const projectService = session.getProjectService();

            // Configure the deferred extension.
            const extraFileExtensions = [{ extension: ".deferred", scriptKind: ScriptKind.Deferred, isMixedContent: true }];
            const configureHostRequest = makeSessionRequest<protocol.ConfigureRequestArguments>(CommandNames.Configure, { extraFileExtensions });
            session.executeCommand(configureHostRequest);

            // Open external project
            const projectName = "/proj1";
            projectService.openExternalProject({
                projectFileName: projectName,
                rootFiles: toExternalFiles([file1.path, file2.path, tsconfig.path]),
                options: {}
            });

            // Assert
            checkNumberOfProjects(projectService, { configuredProjects: 1 });

            const configuredProject = configuredProjectAt(projectService, 0);
            checkProjectActualFiles(configuredProject, [file1.path, tsconfig.path]);

            // Allow allowNonTsExtensions will be set to true for deferred extensions.
            assert.isTrue(configuredProject.getCompilerOptions().allowNonTsExtensions);
        });

        it("Orphan source files are handled correctly on watch trigger", () => {
            const projectLocation = "/user/username/projects/project";
            const file1: File = {
                path: `${projectLocation}/src/file1.ts`,
                content: `export let x = 10;`
            };
            const file2: File = {
                path: `${projectLocation}/src/file2.ts`,
                content: "export let y = 10;"
            };
            const configContent1 = JSON.stringify({
                files: ["src/file1.ts", "src/file2.ts"]
            });
            const config: File = {
                path: `${projectLocation}/tsconfig.json`,
                content: configContent1
            };
            const files = [file1, file2, libFile, config];
            const host = createServerHost(files);
            const service = createProjectService(host);
            service.openClientFile(file1.path);
            checkProjectActualFiles(service.configuredProjects.get(config.path)!, [file1.path, file2.path, libFile.path, config.path]);

            const configContent2 = JSON.stringify({
                files: ["src/file1.ts"]
            });
            config.content = configContent2;
            host.reloadFS(files);
            host.runQueuedTimeoutCallbacks();

            checkProjectActualFiles(service.configuredProjects.get(config.path)!, [file1.path, libFile.path, config.path]);
            verifyFile2InfoIsOrphan();

            file2.content += "export let z = 10;";
            host.reloadFS(files);
            host.runQueuedTimeoutCallbacks();

            checkProjectActualFiles(service.configuredProjects.get(config.path)!, [file1.path, libFile.path, config.path]);
            verifyFile2InfoIsOrphan();

            function verifyFile2InfoIsOrphan() {
                const info = Debug.assertDefined(service.getScriptInfoForPath(file2.path as Path));
                assert.equal(info.containingProjects.length, 0);
            }
        });

        it("handles delayed directory watch invoke on file creation", () => {
            const projectRootPath = "/users/username/projects/project";
            const fileB: File = {
                path: `${projectRootPath}/b.ts`,
                content: "export const b = 10;"
            };
            const fileA: File = {
                path: `${projectRootPath}/a.ts`,
                content: "export const a = 10;"
            };
            const fileSubA: File = {
                path: `${projectRootPath}/sub/a.ts`,
                content: fileA.content
            };
            const config: File = {
                path: `${projectRootPath}/tsconfig.json`,
                content: "{}"
            };
            const files = [fileSubA, fileB, config, libFile];
            const host = createServerHost(files);
            const { logger, hasErrorMsg } = createHasErrorMessageLogger();
            const session = createSession(host, { canUseEvents: true, noGetErrOnBackgroundUpdate: true, logger });
            openFile(fileB);
            openFile(fileSubA);

            const services = session.getProjectService();
            checkNumberOfProjects(services, { configuredProjects: 1 });
            checkProjectActualFiles(services.configuredProjects.get(config.path)!, files.map(f => f.path));
            host.checkTimeoutQueueLengthAndRun(0);

            // This should schedule 2 timeouts for ensuring project structure and ensuring projects for open file
            const filesWithFileA = files.map(f => f === fileSubA ? fileA : f);
            host.reloadFS(files.map(f => f === fileSubA ? fileA : f));
            host.checkTimeoutQueueLength(2);

            closeFilesForSession([fileSubA], session);
            // This should cancel existing updates and schedule new ones
            host.checkTimeoutQueueLength(2);
            checkNumberOfProjects(services, { configuredProjects: 1 });
            checkProjectActualFiles(services.configuredProjects.get(config.path)!, files.map(f => f.path));

            // Open the fileA (as if rename)
            openFile(fileA);

            // config project is updated to check if fileA is present in it
            checkNumberOfProjects(services, { configuredProjects: 1 });
            checkProjectActualFiles(services.configuredProjects.get(config.path)!, filesWithFileA.map(f => f.path));

            // Run the timeout for updating configured project and ensuring projects for open file
            host.checkTimeoutQueueLengthAndRun(2);
            checkProjectActualFiles(services.configuredProjects.get(config.path)!, filesWithFileA.map(f => f.path));

            // file is deleted but watches are not yet invoked
            const originalFileExists = host.fileExists;
            host.fileExists = s => s === fileA.path ? false : originalFileExists.call(host, s);
            closeFilesForSession([fileA], session);
            host.checkTimeoutQueueLength(2); // Update configured project and projects for open file
            checkProjectActualFiles(services.configuredProjects.get(config.path)!, filesWithFileA.map(f => f.path));

           // host.fileExists = originalFileExists;
            openFile(fileSubA);
            // This should create inferred project since fileSubA not on the disk
            checkProjectActualFiles(services.configuredProjects.get(config.path)!, mapDefined(filesWithFileA, f => f === fileA ? undefined : f.path));
            checkProjectActualFiles(services.inferredProjects[0], [fileSubA.path, libFile.path]);

            host.checkTimeoutQueueLengthAndRun(2); // Update configured project and projects for open file
            host.fileExists = originalFileExists;

            // Actually trigger the file move
            host.reloadFS(files);
            host.checkTimeoutQueueLength(2);
            const fileBErrorTimeoutId = host.getNextTimeoutId();

            session.executeCommandSeq<protocol.GeterrRequest>({
                command: protocol.CommandTypes.Geterr,
                arguments: {
                    files: [fileB.path, fileSubA.path],
                    delay: 0
                }
            });
            const getErrSeqId = session.getSeq();
            host.checkTimeoutQueueLength(3);

            session.clearMessages();
            host.runQueuedTimeoutCallbacks(fileBErrorTimeoutId);
            checkErrorMessage(session, "syntaxDiag", { file: fileB.path, diagnostics: [] });

            session.clearMessages();
            host.runQueuedImmediateCallbacks();
            checkErrorMessage(session, "semanticDiag", { file: fileB.path, diagnostics: [] });

            session.clearMessages();
            const fileSubAErrorTimeoutId = host.getNextTimeoutId();
            host.runQueuedImmediateCallbacks();
            checkErrorMessage(session, "suggestionDiag", { file: fileB.path, diagnostics: [] });

            session.clearMessages();
            host.checkTimeoutQueueLength(3);
            host.runQueuedTimeoutCallbacks(fileSubAErrorTimeoutId);
            checkCompleteEvent(session, 1, getErrSeqId);
            assert.isFalse(hasErrorMsg());

            function openFile(file: File) {
                openFilesForSession([{ file, projectRootPath }], session);
            }
        });
    });

    describe("tsserverProjectSystem Proper errors", () => {
        function createErrorLogger() {
            let hasError = false;
            const errorLogger: server.Logger = {
                close: noop,
                hasLevel: () => true,
                loggingEnabled: () => true,
                perftrc: noop,
                info: noop,
                msg: (_s, type) => {
                    if (type === server.Msg.Err) {
                        hasError = true;
                    }
                },
                startGroup: noop,
                endGroup: noop,
                getLogFileName: () => undefined
            };
            return {
                errorLogger,
                hasError: () => hasError
            };
        }

        it("document is not contained in project", () => {
            const file1 = {
                path: "/a/b/app.ts",
                content: ""
            };
            const corruptedConfig = {
                path: "/a/b/tsconfig.json",
                content: "{"
            };
            const host = createServerHost([file1, corruptedConfig]);
            const projectService = createProjectService(host);

            projectService.openClientFile(file1.path);
            projectService.checkNumberOfProjects({ configuredProjects: 1 });

            const project = projectService.findProject(corruptedConfig.path)!;
            checkProjectRootFiles(project, [file1.path]);
        });

        describe("when opening new file that doesnt exist on disk yet", () => {
            function verifyNonExistentFile(useProjectRoot: boolean) {
                const host = createServerHost([libFile]);
                const { hasError, errorLogger } = createErrorLogger();
                const session = createSession(host, { canUseEvents: true, logger: errorLogger, useInferredProjectPerProjectRoot: true });

                const folderPath = "/user/someuser/projects/someFolder";
                const projectService = session.getProjectService();
                const untitledFile = "untitled:Untitled-1";
                session.executeCommandSeq<protocol.OpenRequest>({
                    command: server.CommandNames.Open,
                    arguments: {
                        file: untitledFile,
                        fileContent: "",
                        scriptKindName: "JS",
                        projectRootPath: useProjectRoot ? folderPath : undefined
                    }
                });
                checkNumberOfProjects(projectService, { inferredProjects: 1 });
                const infoForUntitledAtProjectRoot = projectService.getScriptInfoForPath(`${folderPath.toLowerCase()}/${untitledFile.toLowerCase()}` as Path);
                const infoForUnitiledAtRoot = projectService.getScriptInfoForPath(`/${untitledFile.toLowerCase()}` as Path);
                if (useProjectRoot) {
                    assert.isDefined(infoForUntitledAtProjectRoot);
                    assert.isUndefined(infoForUnitiledAtRoot);
                }
                else {
                    assert.isDefined(infoForUnitiledAtRoot);
                    assert.isUndefined(infoForUntitledAtProjectRoot);
                }
                host.checkTimeoutQueueLength(2);

                const newTimeoutId = host.getNextTimeoutId();
                const expectedSequenceId = session.getNextSeq();
                session.executeCommandSeq<protocol.GeterrRequest>({
                    command: server.CommandNames.Geterr,
                    arguments: {
                        delay: 0,
                        files: [untitledFile]
                    }
                });
                host.checkTimeoutQueueLength(3);

                // Run the last one = get error request
                host.runQueuedTimeoutCallbacks(newTimeoutId);

                assert.isFalse(hasError());
                host.checkTimeoutQueueLength(2);
                checkErrorMessage(session, "syntaxDiag", { file: untitledFile, diagnostics: [] });
                session.clearMessages();

                host.runQueuedImmediateCallbacks();
                assert.isFalse(hasError());
                checkErrorMessage(session, "semanticDiag", { file: untitledFile, diagnostics: [] });
                session.clearMessages();

                host.runQueuedImmediateCallbacks(1);
                assert.isFalse(hasError());
                checkErrorMessage(session, "suggestionDiag", { file: untitledFile, diagnostics: [] });
                checkCompleteEvent(session, 2, expectedSequenceId);
                session.clearMessages();
            }

            it("has projectRoot", () => {
                verifyNonExistentFile(/*useProjectRoot*/ true);
            });

            it("does not have projectRoot", () => {
                verifyNonExistentFile(/*useProjectRoot*/ false);
            });
        });

        it("folder rename updates project structure and reports no errors", () => {
            const projectDir = "/a/b/projects/myproject";
            const app: File = {
                path: `${projectDir}/bar/app.ts`,
                content: "class Bar implements foo.Foo { getFoo() { return ''; } get2() { return 1; } }"
            };
            const foo: File = {
                path: `${projectDir}/foo/foo.ts`,
                content: "declare namespace foo { interface Foo { get2(): number; getFoo(): string; } }"
            };
            const configFile: File = {
                path: `${projectDir}/tsconfig.json`,
                content: JSON.stringify({ compilerOptions: { module: "none", targer: "es5" }, exclude: ["node_modules"] })
            };
            const host = createServerHost([app, foo, configFile]);
            const session = createSession(host, { canUseEvents: true, });
            const projectService = session.getProjectService();

            session.executeCommandSeq<protocol.OpenRequest>({
                command: server.CommandNames.Open,
                arguments: { file: app.path, }
            });
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            assert.isDefined(projectService.configuredProjects.get(configFile.path));
            verifyErrorsInApp();

            host.renameFolder(`${projectDir}/foo`, `${projectDir}/foo2`);
            host.runQueuedTimeoutCallbacks();
            host.runQueuedTimeoutCallbacks();
            verifyErrorsInApp();

            function verifyErrorsInApp() {
                session.clearMessages();
                const expectedSequenceId = session.getNextSeq();
                session.executeCommandSeq<protocol.GeterrRequest>({
                    command: server.CommandNames.Geterr,
                    arguments: {
                        delay: 0,
                        files: [app.path]
                    }
                });
                host.checkTimeoutQueueLengthAndRun(1);
                checkErrorMessage(session, "syntaxDiag", { file: app.path, diagnostics: [] });
                session.clearMessages();

                host.runQueuedImmediateCallbacks();
                checkErrorMessage(session, "semanticDiag", { file: app.path, diagnostics: [] });
                session.clearMessages();

                host.runQueuedImmediateCallbacks(1);
                checkErrorMessage(session, "suggestionDiag", { file: app.path, diagnostics: [] });
                checkCompleteEvent(session, 2, expectedSequenceId);
                session.clearMessages();
            }
        });

        it("Getting errors before opening file", () => {
            const file: File = {
                path: "/a/b/project/file.ts",
                content: "let x: number = false;"
            };
            const host = createServerHost([file, libFile]);
            const { hasError, errorLogger } = createErrorLogger();
            const session = createSession(host, { canUseEvents: true, logger: errorLogger });

            session.clearMessages();
            const expectedSequenceId = session.getNextSeq();
            session.executeCommandSeq<protocol.GeterrRequest>({
                command: server.CommandNames.Geterr,
                arguments: {
                    delay: 0,
                    files: [file.path]
                }
            });

            host.runQueuedImmediateCallbacks();
            assert.isFalse(hasError());
            checkCompleteEvent(session, 1, expectedSequenceId);
            session.clearMessages();
        });

        it("Reports errors correctly when file referenced by inferred project root, is opened right after closing the root file", () => {
            const projectRoot = "/user/username/projects/myproject";
            const app: File = {
                path: `${projectRoot}/src/client/app.js`,
                content: ""
            };
            const serverUtilities: File = {
                path: `${projectRoot}/src/server/utilities.js`,
                content: `function getHostName() { return "hello"; } export { getHostName };`
            };
            const backendTest: File = {
                path: `${projectRoot}/test/backend/index.js`,
                content: `import { getHostName } from '../../src/server/utilities';export default getHostName;`
            };
            const files = [libFile, app, serverUtilities, backendTest];
            const host = createServerHost(files);
            const session = createSession(host, { useInferredProjectPerProjectRoot: true, canUseEvents: true });
            openFilesForSession([{ file: app, projectRootPath: projectRoot }], session);
            const service = session.getProjectService();
            checkNumberOfProjects(service, { inferredProjects: 1 });
            const project = service.inferredProjects[0];
            checkProjectActualFiles(project, [libFile.path, app.path]);
            openFilesForSession([{ file: backendTest, projectRootPath: projectRoot }], session);
            checkNumberOfProjects(service, { inferredProjects: 1 });
            checkProjectActualFiles(project, files.map(f => f.path));
            checkErrors([backendTest.path, app.path]);
            closeFilesForSession([backendTest], session);
            openFilesForSession([{ file: serverUtilities.path, projectRootPath: projectRoot }], session);
            checkErrors([serverUtilities.path, app.path]);

            function checkErrors(openFiles: [string, string]) {
                const expectedSequenceId = session.getNextSeq();
                session.executeCommandSeq<protocol.GeterrRequest>({
                    command: protocol.CommandTypes.Geterr,
                    arguments: {
                        delay: 0,
                        files: openFiles
                    }
                });

                for (const openFile of openFiles) {
                    session.clearMessages();
                    host.checkTimeoutQueueLength(3);
                    host.runQueuedTimeoutCallbacks(host.getNextTimeoutId() - 1);

                    checkErrorMessage(session, "syntaxDiag", { file: openFile, diagnostics: [] });
                    session.clearMessages();

                    host.runQueuedImmediateCallbacks();
                    checkErrorMessage(session, "semanticDiag", { file: openFile, diagnostics: [] });
                    session.clearMessages();

                    host.runQueuedImmediateCallbacks(1);
                    checkErrorMessage(session, "suggestionDiag", { file: openFile, diagnostics: [] });
                }
                checkCompleteEvent(session, 2, expectedSequenceId);
                session.clearMessages();
            }
        });
    });

    describe("tsserverProjectSystem autoDiscovery", () => {
        it("does not depend on extension", () => {
            const file1 = {
                path: "/a/b/app.html",
                content: ""
            };
            const file2 = {
                path: "/a/b/app.d.ts",
                content: ""
            };
            const host = createServerHost([file1, file2]);
            const projectService = createProjectService(host);
            projectService.openExternalProject({
                projectFileName: "/a/b/proj.csproj",
                rootFiles: [toExternalFile(file2.path), { fileName: file1.path, hasMixedContent: true, scriptKind: ScriptKind.JS }],
                options: {}
            });
            projectService.checkNumberOfProjects({ externalProjects: 1 });
            const typeAcquisition = projectService.externalProjects[0].getTypeAcquisition();
            assert.isTrue(typeAcquisition.enable, "Typine acquisition should be enabled");
        });
    });

    describe("tsserverProjectSystem extra resolution pass in lshost", () => {
        it("can load typings that are proper modules", () => {
            const file1 = {
                path: "/a/b/app.js",
                content: `var x = require("lib")`
            };
            const lib = {
                path: "/a/cache/node_modules/@types/lib/index.d.ts",
                content: "export let x = 1"
            };
            const host: TestServerHost & ModuleResolutionHost = createServerHost([file1, lib]);
            const resolutionTrace = createHostModuleResolutionTrace(host);
            const projectService = createProjectService(host, { typingsInstaller: new TestTypingsInstaller("/a/cache", /*throttleLimit*/5, host) });

            projectService.setCompilerOptionsForInferredProjects({ traceResolution: true, allowJs: true });
            projectService.openClientFile(file1.path);
            projectService.checkNumberOfProjects({ inferredProjects: 1 });
            const proj = projectService.inferredProjects[0];

            assert.deepEqual(resolutionTrace, [
                "======== Resolving module 'lib' from '/a/b/app.js'. ========",
                "Module resolution kind is not specified, using 'NodeJs'.",
                "Loading module 'lib' from 'node_modules' folder, target file type 'TypeScript'.",
                "Directory '/a/b/node_modules' does not exist, skipping all lookups in it.",
                "Directory '/a/node_modules' does not exist, skipping all lookups in it.",
                "Directory '/node_modules' does not exist, skipping all lookups in it.",
                "Loading module 'lib' from 'node_modules' folder, target file type 'JavaScript'.",
                "Directory '/a/b/node_modules' does not exist, skipping all lookups in it.",
                "Directory '/a/node_modules' does not exist, skipping all lookups in it.",
                "Directory '/node_modules' does not exist, skipping all lookups in it.",
                "======== Module name 'lib' was not resolved. ========",
                `Auto discovery for typings is enabled in project '${proj.getProjectName()}'. Running extra resolution pass for module 'lib' using cache location '/a/cache'.`,
                "File '/a/cache/node_modules/lib.d.ts' does not exist.",
                "File '/a/cache/node_modules/@types/lib/package.json' does not exist.",
                "File '/a/cache/node_modules/@types/lib.d.ts' does not exist.",
                "File '/a/cache/node_modules/@types/lib/index.d.ts' exist - use it as a name resolution result.",
            ]);
            checkProjectActualFiles(proj, [file1.path, lib.path]);
        });
    });

    describe("tsserverProjectSystem navigate-to for javascript project", () => {
        function containsNavToItem(items: protocol.NavtoItem[], itemName: string, itemKind: string) {
            return find(items, item => item.name === itemName && item.kind === itemKind) !== undefined;
        }

        it("should not include type symbols", () => {
            const file1: File = {
                path: "/a/b/file1.js",
                content: "function foo() {}"
            };
            const configFile: File = {
                path: "/a/b/jsconfig.json",
                content: "{}"
            };
            const host = createServerHost([file1, configFile, libFile]);
            const session = createSession(host);
            openFilesForSession([file1], session);

            // Try to find some interface type defined in lib.d.ts
            const libTypeNavToRequest = makeSessionRequest<protocol.NavtoRequestArgs>(CommandNames.Navto, { searchValue: "Document", file: file1.path, projectFileName: configFile.path });
            const items = session.executeCommand(libTypeNavToRequest).response as protocol.NavtoItem[];
            assert.isFalse(containsNavToItem(items, "Document", "interface"), `Found lib.d.ts symbol in JavaScript project nav to request result.`);

            const localFunctionNavToRequst = makeSessionRequest<protocol.NavtoRequestArgs>(CommandNames.Navto, { searchValue: "foo", file: file1.path, projectFileName: configFile.path });
            const items2 = session.executeCommand(localFunctionNavToRequst).response as protocol.NavtoItem[];
            assert.isTrue(containsNavToItem(items2, "foo", "function"), `Cannot find function symbol "foo".`);
        });
    });

    describe("tsserverProjectSystem external projects", () => {
        it("correctly handling add/remove tsconfig - 1", () => {
            const f1 = {
                path: "/a/b/app.ts",
                content: "let x = 1;"
            };
            const f2 = {
                path: "/a/b/lib.ts",
                content: ""
            };
            const tsconfig = {
                path: "/a/b/tsconfig.json",
                content: ""
            };
            const host = createServerHost([f1, f2]);
            const projectService = createProjectService(host);

            // open external project
            const projectName = "/a/b/proj1";
            projectService.openExternalProject({
                projectFileName: projectName,
                rootFiles: toExternalFiles([f1.path, f2.path]),
                options: {}
            });
            projectService.openClientFile(f1.path);
            projectService.checkNumberOfProjects({ externalProjects: 1 });
            checkProjectActualFiles(projectService.externalProjects[0], [f1.path, f2.path]);

            // rename lib.ts to tsconfig.json
            host.reloadFS([f1, tsconfig]);
            projectService.openExternalProject({
                projectFileName: projectName,
                rootFiles: toExternalFiles([f1.path, tsconfig.path]),
                options: {}
            });
            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [f1.path, tsconfig.path]);

            // rename tsconfig.json back to lib.ts
            host.reloadFS([f1, f2]);
            projectService.openExternalProject({
                projectFileName: projectName,
                rootFiles: toExternalFiles([f1.path, f2.path]),
                options: {}
            });

            projectService.checkNumberOfProjects({ externalProjects: 1 });
            checkProjectActualFiles(projectService.externalProjects[0], [f1.path, f2.path]);
        });


        it("correctly handling add/remove tsconfig - 2", () => {
            const f1 = {
                path: "/a/b/app.ts",
                content: "let x = 1;"
            };
            const cLib = {
                path: "/a/b/c/lib.ts",
                content: ""
            };
            const cTsconfig = {
                path: "/a/b/c/tsconfig.json",
                content: "{}"
            };
            const dLib = {
                path: "/a/b/d/lib.ts",
                content: ""
            };
            const dTsconfig = {
                path: "/a/b/d/tsconfig.json",
                content: "{}"
            };
            const host = createServerHost([f1, cLib, cTsconfig, dLib, dTsconfig]);
            const projectService = createProjectService(host);

            // open external project
            const projectName = "/a/b/proj1";
            projectService.openExternalProject({
                projectFileName: projectName,
                rootFiles: toExternalFiles([f1.path]),
                options: {}
            });

            projectService.checkNumberOfProjects({ externalProjects: 1 });
            checkProjectActualFiles(projectService.externalProjects[0], [f1.path]);

            // add two config file as root files
            projectService.openExternalProject({
                projectFileName: projectName,
                rootFiles: toExternalFiles([f1.path, cTsconfig.path, dTsconfig.path]),
                options: {}
            });
            projectService.checkNumberOfProjects({ configuredProjects: 2 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [cLib.path, cTsconfig.path]);
            checkProjectActualFiles(configuredProjectAt(projectService, 1), [dLib.path, dTsconfig.path]);

            // remove one config file
            projectService.openExternalProject({
                projectFileName: projectName,
                rootFiles: toExternalFiles([f1.path, dTsconfig.path]),
                options: {}
            });

            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [dLib.path, dTsconfig.path]);

            // remove second config file
            projectService.openExternalProject({
                projectFileName: projectName,
                rootFiles: toExternalFiles([f1.path]),
                options: {}
            });

            projectService.checkNumberOfProjects({ externalProjects: 1 });
            checkProjectActualFiles(projectService.externalProjects[0], [f1.path]);

            // open two config files
            // add two config file as root files
            projectService.openExternalProject({
                projectFileName: projectName,
                rootFiles: toExternalFiles([f1.path, cTsconfig.path, dTsconfig.path]),
                options: {}
            });
            projectService.checkNumberOfProjects({ configuredProjects: 2 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [cLib.path, cTsconfig.path]);
            checkProjectActualFiles(configuredProjectAt(projectService, 1), [dLib.path, dTsconfig.path]);

            // close all projects - no projects should be opened
            projectService.closeExternalProject(projectName);
            projectService.checkNumberOfProjects({});
        });

        it("correctly handles changes in lib section of config file", () => {
            const libES5 = {
                path: "/compiler/lib.es5.d.ts",
                content: "declare const eval: any"
            };
            const libES2015Promise = {
                path: "/compiler/lib.es2015.promise.d.ts",
                content: "declare class Promise<T> {}"
            };
            const app = {
                path: "/src/app.ts",
                content: "var x: Promise<string>;"
            };
            const config1 = {
                path: "/src/tsconfig.json",
                content: JSON.stringify(
                    {
                        compilerOptions: {
                            module: "commonjs",
                            target: "es5",
                            noImplicitAny: true,
                            sourceMap: false,
                            lib: [
                                "es5"
                            ]
                        }
                    })
            };
            const config2 = {
                path: config1.path,
                content: JSON.stringify(
                    {
                        compilerOptions: {
                            module: "commonjs",
                            target: "es5",
                            noImplicitAny: true,
                            sourceMap: false,
                            lib: [
                                "es5",
                                "es2015.promise"
                            ]
                        }
                    })
            };
            const host = createServerHost([libES5, libES2015Promise, app, config1], { executingFilePath: "/compiler/tsc.js" });
            const projectService = createProjectService(host);
            projectService.openClientFile(app.path);

            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [libES5.path, app.path, config1.path]);

            host.reloadFS([libES5, libES2015Promise, app, config2]);
            host.checkTimeoutQueueLengthAndRun(2);

            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [libES5.path, libES2015Promise.path, app.path, config2.path]);
        });

        it("should handle non-existing directories in config file", () => {
            const f = {
                path: "/a/src/app.ts",
                content: "let x = 1;"
            };
            const config = {
                path: "/a/tsconfig.json",
                content: JSON.stringify({
                    compilerOptions: {},
                    include: [
                        "src/**/*",
                        "notexistingfolder/*"
                    ]
                })
            };
            const host = createServerHost([f, config]);
            const projectService = createProjectService(host);
            projectService.openClientFile(f.path);
            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            const project = projectService.configuredProjects.get(config.path)!;
            assert.isTrue(project.hasOpenRef()); // f

            projectService.closeClientFile(f.path);
            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            assert.strictEqual(projectService.configuredProjects.get(config.path), project);
            assert.isFalse(project.hasOpenRef()); // No files
            assert.isFalse(project.isClosed());

            projectService.openClientFile(f.path);
            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            assert.strictEqual(projectService.configuredProjects.get(config.path), project);
            assert.isTrue(project.hasOpenRef()); // f
            assert.isFalse(project.isClosed());
        });
    });

    describe("tsserverProjectSystem prefer typings to js", () => {
        it("during second resolution pass", () => {
            const typingsCacheLocation = "/a/typings";
            const f1 = {
                path: "/a/b/app.js",
                content: "var x = require('bar')"
            };
            const barjs = {
                path: "/a/b/node_modules/bar/index.js",
                content: "export let x = 1"
            };
            const barTypings = {
                path: `${typingsCacheLocation}/node_modules/@types/bar/index.d.ts`,
                content: "export let y: number"
            };
            const config = {
                path: "/a/b/jsconfig.json",
                content: JSON.stringify({ compilerOptions: { allowJs: true }, exclude: ["node_modules"] })
            };
            const host = createServerHost([f1, barjs, barTypings, config]);
            const projectService = createProjectService(host, { typingsInstaller: new TestTypingsInstaller(typingsCacheLocation, /*throttleLimit*/ 5, host) });

            projectService.openClientFile(f1.path);
            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [f1.path, barTypings.path, config.path]);
        });
    });

    describe("tsserverProjectSystem format settings", () => {
        it("can be set globally", () => {
            const f1 = {
                path: "/a/b/app.ts",
                content: "let x;"
            };
            const host = createServerHost([f1]);
            const projectService = createProjectService(host);
            projectService.openClientFile(f1.path);

            const defaultSettings = projectService.getFormatCodeOptions(f1.path as server.NormalizedPath);

            // set global settings
            const newGlobalSettings1 = clone(defaultSettings);
            newGlobalSettings1.placeOpenBraceOnNewLineForControlBlocks = !newGlobalSettings1.placeOpenBraceOnNewLineForControlBlocks;
            projectService.setHostConfiguration({ formatOptions: newGlobalSettings1 });

            // get format options for file - should be equal to new global settings
            const s1 = projectService.getFormatCodeOptions(server.toNormalizedPath(f1.path));
            assert.deepEqual(s1, newGlobalSettings1, "file settings should be the same with global settings");

            // set per file format options
            const newPerFileSettings = clone(defaultSettings);
            newPerFileSettings.insertSpaceAfterCommaDelimiter = !newPerFileSettings.insertSpaceAfterCommaDelimiter;
            projectService.setHostConfiguration({ formatOptions: newPerFileSettings, file: f1.path });

            // get format options for file - should be equal to new per-file settings
            const s2 = projectService.getFormatCodeOptions(server.toNormalizedPath(f1.path));
            assert.deepEqual(s2, newPerFileSettings, "file settings should be the same with per-file settings");

            // set new global settings - they should not affect ones that were set per-file
            const newGlobalSettings2 = clone(defaultSettings);
            newGlobalSettings2.insertSpaceAfterSemicolonInForStatements = !newGlobalSettings2.insertSpaceAfterSemicolonInForStatements;
            projectService.setHostConfiguration({ formatOptions: newGlobalSettings2 });

            // get format options for file - should be equal to new per-file settings
            const s3 = projectService.getFormatCodeOptions(server.toNormalizedPath(f1.path));
            assert.deepEqual(s3, newPerFileSettings, "file settings should still be the same with per-file settings");
        });
    });

    describe("tsserverProjectSystem watching @types", () => {
        it("works correctly when typings are added or removed", () => {
            const f1 = {
                path: "/a/b/app.ts",
                content: "let x = 1;"
            };
            const t1 = {
                path: "/a/b/node_modules/@types/lib1/index.d.ts",
                content: "export let a: number"
            };
            const t2 = {
                path: "/a/b/node_modules/@types/lib2/index.d.ts",
                content: "export let b: number"
            };
            const tsconfig = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({
                    compilerOptions: {},
                    exclude: ["node_modules"]
                })
            };
            const host = createServerHost([f1, t1, tsconfig]);
            const projectService = createProjectService(host);

            projectService.openClientFile(f1.path);
            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [f1.path, t1.path, tsconfig.path]);

            // delete t1
            host.reloadFS([f1, tsconfig]);
            // run throttled operation
            host.runQueuedTimeoutCallbacks();

            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [f1.path, tsconfig.path]);

            // create t2
            host.reloadFS([f1, tsconfig, t2]);
            // run throttled operation
            host.runQueuedTimeoutCallbacks();

            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [f1.path, t2.path, tsconfig.path]);
        });
    });

    describe("tsserverProjectSystem Open-file", () => {
        it("can be reloaded with empty content", () => {
            const f = {
                path: "/a/b/app.ts",
                content: "let x = 1"
            };
            const projectFileName = "externalProject";
            const host = createServerHost([f]);
            const projectService = createProjectService(host);
            // create a project
            projectService.openExternalProject({ projectFileName, rootFiles: [toExternalFile(f.path)], options: {} });
            projectService.checkNumberOfProjects({ externalProjects: 1 });

            const p = projectService.externalProjects[0];
            // force to load the content of the file
            p.updateGraph();

            const scriptInfo = p.getScriptInfo(f.path)!;
            checkSnapLength(scriptInfo.getSnapshot(), f.content.length);

            // open project and replace its content with empty string
            projectService.openClientFile(f.path, "");
            checkSnapLength(scriptInfo.getSnapshot(), 0);
        });
        function checkSnapLength(snap: IScriptSnapshot, expectedLength: number) {
            assert.equal(snap.getLength(), expectedLength, "Incorrect snapshot size");
        }

        function verifyOpenFileWorks(useCaseSensitiveFileNames: boolean) {
            const file1: File = {
                path: "/a/b/src/app.ts",
                content: "let x = 10;"
            };
            const file2: File = {
                path: "/a/B/lib/module2.ts",
                content: "let z = 10;"
            };
            const configFile: File = {
                path: "/a/b/tsconfig.json",
                content: ""
            };
            const configFile2: File = {
                path: "/a/tsconfig.json",
                content: ""
            };
            const host = createServerHost([file1, file2, configFile, configFile2], {
                useCaseSensitiveFileNames
            });
            const service = createProjectService(host);

            // Open file1 -> configFile
            verifyConfigFileName(file1, "/a", configFile);
            verifyConfigFileName(file1, "/a/b", configFile);
            verifyConfigFileName(file1, "/a/B", configFile);

            // Open file2 use root "/a/b"
            verifyConfigFileName(file2, "/a", useCaseSensitiveFileNames ? configFile2 : configFile);
            verifyConfigFileName(file2, "/a/b", useCaseSensitiveFileNames ? configFile2 : configFile);
            verifyConfigFileName(file2, "/a/B", useCaseSensitiveFileNames ? undefined : configFile);

            function verifyConfigFileName(file: File, projectRoot: string, expectedConfigFile: File | undefined) {
                const { configFileName } = service.openClientFile(file.path, /*fileContent*/ undefined, /*scriptKind*/ undefined, projectRoot);
                assert.equal(configFileName, expectedConfigFile && expectedConfigFile.path);
                service.closeClientFile(file.path);
            }
        }
        it("works when project root is used with case-sensitive system", () => {
            verifyOpenFileWorks(/*useCaseSensitiveFileNames*/ true);
        });

        it("works when project root is used with case-insensitive system", () => {
            verifyOpenFileWorks(/*useCaseSensitiveFileNames*/ false);
        });

        it("uses existing project even if project refresh is pending", () => {
            const projectFolder = "/user/someuser/projects/myproject";
            const aFile: File = {
                path: `${projectFolder}/src/a.ts`,
                content: "export const x = 0;"
            };
            const configFile: File = {
                path: `${projectFolder}/tsconfig.json`,
                content: "{}"
            };
            const files = [aFile, configFile, libFile];
            const host = createServerHost(files);
            const service = createProjectService(host);
            service.openClientFile(aFile.path, /*fileContent*/ undefined, ScriptKind.TS, projectFolder);
            verifyProject();

            const bFile: File = {
                path: `${projectFolder}/src/b.ts`,
                content: `export {}; declare module "./a" {  export const y: number; }`
            };
            files.push(bFile);
            host.reloadFS(files);
            service.openClientFile(bFile.path, /*fileContent*/ undefined, ScriptKind.TS, projectFolder);
            verifyProject();

            function verifyProject() {
                assert.isDefined(service.configuredProjects.get(configFile.path));
                const project = service.configuredProjects.get(configFile.path)!;
                checkProjectActualFiles(project, files.map(f => f.path));
            }
        });
    });

    describe("tsserverProjectSystem Language service", () => {
        it("should work correctly on case-sensitive file systems", () => {
            const lib = {
                path: "/a/Lib/lib.d.ts",
                content: "let x: number"
            };
            const f = {
                path: "/a/b/app.ts",
                content: "let x = 1;"
            };
            const host = createServerHost([lib, f], { executingFilePath: "/a/Lib/tsc.js", useCaseSensitiveFileNames: true });
            const projectService = createProjectService(host);
            projectService.openClientFile(f.path);
            projectService.checkNumberOfProjects({ inferredProjects: 1 });
            projectService.inferredProjects[0].getLanguageService().getProgram();
        });
    });

    describe("tsserverProjectSystem rename a module file and rename back", () => {
        it("should restore the states for inferred projects", () => {
            const moduleFile = {
                path: "/a/b/moduleFile.ts",
                content: "export function bar() { };"
            };
            const file1 = {
                path: "/a/b/file1.ts",
                content: "import * as T from './moduleFile'; T.bar();"
            };
            const host = createServerHost([moduleFile, file1]);
            const session = createSession(host);

            openFilesForSession([file1], session);
            const getErrRequest = makeSessionRequest<server.protocol.SemanticDiagnosticsSyncRequestArgs>(
                server.CommandNames.SemanticDiagnosticsSync,
                { file: file1.path }
            );
            let diags = session.executeCommand(getErrRequest).response as server.protocol.Diagnostic[];
            verifyNoDiagnostics(diags);

            const moduleFileOldPath = moduleFile.path;
            const moduleFileNewPath = "/a/b/moduleFile1.ts";
            moduleFile.path = moduleFileNewPath;
            host.reloadFS([moduleFile, file1]);
            host.runQueuedTimeoutCallbacks();
            diags = session.executeCommand(getErrRequest).response as server.protocol.Diagnostic[];
            verifyDiagnostics(diags, [
                { diagnosticMessage: Diagnostics.Cannot_find_module_0, errorTextArguments: ["./moduleFile"] }
            ]);
            assert.equal(diags.length, 1);

            moduleFile.path = moduleFileOldPath;
            host.reloadFS([moduleFile, file1]);
            host.runQueuedTimeoutCallbacks();

            // Make a change to trigger the program rebuild
            const changeRequest = makeSessionRequest<server.protocol.ChangeRequestArgs>(
                server.CommandNames.Change,
                { file: file1.path, line: 1, offset: 44, endLine: 1, endOffset: 44, insertString: "\n" }
            );
            session.executeCommand(changeRequest);
            host.runQueuedTimeoutCallbacks();

            diags = session.executeCommand(getErrRequest).response as server.protocol.Diagnostic[];
            verifyNoDiagnostics(diags);
        });

        it("should restore the states for configured projects", () => {
            const moduleFile = {
                path: "/a/b/moduleFile.ts",
                content: "export function bar() { };"
            };
            const file1 = {
                path: "/a/b/file1.ts",
                content: "import * as T from './moduleFile'; T.bar();"
            };
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: `{}`
            };
            const host = createServerHost([moduleFile, file1, configFile]);
            const session = createSession(host);

            openFilesForSession([file1], session);
            const getErrRequest = makeSessionRequest<server.protocol.SemanticDiagnosticsSyncRequestArgs>(
                server.CommandNames.SemanticDiagnosticsSync,
                { file: file1.path }
            );
            let diags = session.executeCommand(getErrRequest).response as server.protocol.Diagnostic[];
            verifyNoDiagnostics(diags);

            const moduleFileOldPath = moduleFile.path;
            const moduleFileNewPath = "/a/b/moduleFile1.ts";
            moduleFile.path = moduleFileNewPath;
            host.reloadFS([moduleFile, file1, configFile]);
            host.runQueuedTimeoutCallbacks();
            diags = session.executeCommand(getErrRequest).response as server.protocol.Diagnostic[];
            verifyDiagnostics(diags, [
                { diagnosticMessage: Diagnostics.Cannot_find_module_0, errorTextArguments: ["./moduleFile"] }
            ]);

            moduleFile.path = moduleFileOldPath;
            host.reloadFS([moduleFile, file1, configFile]);
            host.runQueuedTimeoutCallbacks();
            diags = session.executeCommand(getErrRequest).response as server.protocol.Diagnostic[];
            verifyNoDiagnostics(diags);
        });

        it("should property handle missing config files", () => {
            const f1 = {
                path: "/a/b/app.ts",
                content: "let x = 1"
            };
            const config = {
                path: "/a/b/tsconfig.json",
                content: "{}"
            };
            const projectName = "project1";
            const host = createServerHost([f1]);
            const projectService = createProjectService(host);
            projectService.openExternalProject({ rootFiles: toExternalFiles([f1.path, config.path]), options: {}, projectFileName: projectName });

            // should have one external project since config file is missing
            projectService.checkNumberOfProjects({ externalProjects: 1 });

            host.reloadFS([f1, config]);
            projectService.openExternalProject({ rootFiles: toExternalFiles([f1.path, config.path]), options: {}, projectFileName: projectName });
            projectService.checkNumberOfProjects({ configuredProjects: 1 });
        });

        it("types should load from config file path if config exists", () => {
            const f1 = {
                path: "/a/b/app.ts",
                content: "let x = 1"
            };
            const config = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({ compilerOptions: { types: ["node"], typeRoots: [] } })
            };
            const node = {
                path: "/a/b/node_modules/@types/node/index.d.ts",
                content: "declare var process: any"
            };
            const cwd = {
                path: "/a/c"
            };
            const host = createServerHost([f1, config, node, cwd], { currentDirectory: cwd.path });
            const projectService = createProjectService(host);
            projectService.openClientFile(f1.path);
            projectService.checkNumberOfProjects({ configuredProjects: 1 });
            checkProjectActualFiles(configuredProjectAt(projectService, 0), [f1.path, node.path, config.path]);
        });
    });

    describe("tsserverProjectSystem add the missing module file for inferred project", () => {
        it("should remove the `module not found` error", () => {
            const moduleFile = {
                path: "/a/b/moduleFile.ts",
                content: "export function bar() { };"
            };
            const file1 = {
                path: "/a/b/file1.ts",
                content: "import * as T from './moduleFile'; T.bar();"
            };
            const host = createServerHost([file1]);
            const session = createSession(host);
            openFilesForSession([file1], session);
            const getErrRequest = makeSessionRequest<server.protocol.SemanticDiagnosticsSyncRequestArgs>(
                server.CommandNames.SemanticDiagnosticsSync,
                { file: file1.path }
            );
            let diags = session.executeCommand(getErrRequest).response as server.protocol.Diagnostic[];
            verifyDiagnostics(diags, [
                { diagnosticMessage: Diagnostics.Cannot_find_module_0, errorTextArguments: ["./moduleFile"] }
            ]);

            host.reloadFS([file1, moduleFile]);
            host.runQueuedTimeoutCallbacks();

            // Make a change to trigger the program rebuild
            const changeRequest = makeSessionRequest<server.protocol.ChangeRequestArgs>(
                server.CommandNames.Change,
                { file: file1.path, line: 1, offset: 44, endLine: 1, endOffset: 44, insertString: "\n" }
            );
            session.executeCommand(changeRequest);

            // Recheck
            diags = session.executeCommand(getErrRequest).response as server.protocol.Diagnostic[];
            verifyNoDiagnostics(diags);
        });

        it("npm install @types works", () => {
            const folderPath = "/a/b/projects/temp";
            const file1: File = {
                path: `${folderPath}/a.ts`,
                content: 'import f = require("pad"); f;'
            };
            const files = [file1, libFile];
            const host = createServerHost(files);
            const session = createSession(host, { canUseEvents: true });
            const service = session.getProjectService();
            session.executeCommandSeq<protocol.OpenRequest>({
                command: server.CommandNames.Open,
                arguments: {
                    file: file1.path,
                    fileContent: file1.content,
                    scriptKindName: "TS",
                    projectRootPath: folderPath
                }
            });
            checkNumberOfProjects(service, { inferredProjects: 1 });
            session.clearMessages();
            const expectedSequenceId = session.getNextSeq();
            session.executeCommandSeq<protocol.GeterrRequest>({
                command: server.CommandNames.Geterr,
                arguments: {
                    delay: 0,
                    files: [file1.path]
                }
            });

            host.checkTimeoutQueueLengthAndRun(1);
            checkErrorMessage(session, "syntaxDiag", { file: file1.path, diagnostics: [] });
            session.clearMessages();

            host.runQueuedImmediateCallbacks();
            const startOffset = file1.content.indexOf('"') + 1;
            checkErrorMessage(session, "semanticDiag", {
                file: file1.path,
                diagnostics: [
                    createDiagnostic({ line: 1, offset: startOffset }, { line: 1, offset: startOffset + '"pad"'.length }, Diagnostics.Cannot_find_module_0, ["pad"])
                ],
            });
            session.clearMessages();

            host.runQueuedImmediateCallbacks(1);
            checkErrorMessage(session, "suggestionDiag", { file: file1.path, diagnostics: [] });
            checkCompleteEvent(session, 2, expectedSequenceId);
            session.clearMessages();

            const padIndex: File = {
                path: `${folderPath}/node_modules/@types/pad/index.d.ts`,
                content: "export = pad;declare function pad(length: number, text: string, char ?: string): string;"
            };
            files.push(padIndex);
            host.reloadFS(files, { ignoreWatchInvokedWithTriggerAsFileCreate: true });
            host.runQueuedTimeoutCallbacks();
            checkProjectUpdatedInBackgroundEvent(session, [file1.path]);
            session.clearMessages();

            host.runQueuedTimeoutCallbacks();
            checkErrorMessage(session, "syntaxDiag", { file: file1.path, diagnostics: [] });
            session.clearMessages();

            host.runQueuedImmediateCallbacks();
            checkErrorMessage(session, "semanticDiag", { file: file1.path, diagnostics: [] });
        });

        it("suggestion diagnostics", () => {
            const file: File = {
                path: "/a.js",
                content: "function f(p) {}",
            };

            const host = createServerHost([file]);
            const session = createSession(host, { canUseEvents: true });
            const service = session.getProjectService();

            session.executeCommandSeq<protocol.OpenRequest>({
                command: server.CommandNames.Open,
                arguments: { file: file.path, fileContent: file.content },
            });

            checkNumberOfProjects(service, { inferredProjects: 1 });
            session.clearMessages();
            const expectedSequenceId = session.getNextSeq();
            host.checkTimeoutQueueLengthAndRun(2);

            checkProjectUpdatedInBackgroundEvent(session, [file.path]);
            session.clearMessages();

            session.executeCommandSeq<protocol.GeterrRequest>({
                command: server.CommandNames.Geterr,
                arguments: {
                    delay: 0,
                    files: [file.path],
                }
            });

            host.checkTimeoutQueueLengthAndRun(1);

            checkErrorMessage(session, "syntaxDiag", { file: file.path, diagnostics: [] }, /*isMostRecent*/ true);
            session.clearMessages();

            host.runQueuedImmediateCallbacks(1);

            checkErrorMessage(session, "semanticDiag", { file: file.path, diagnostics: [] });
            session.clearMessages();

            host.runQueuedImmediateCallbacks(1);

            checkErrorMessage(session, "suggestionDiag", {
                file: file.path,
                diagnostics: [
                    createDiagnostic({ line: 1, offset: 12 }, { line: 1, offset: 13 }, Diagnostics._0_is_declared_but_its_value_is_never_read, ["p"], "suggestion", /*reportsUnnecssary*/ true)
                ],
            });
            checkCompleteEvent(session, 2, expectedSequenceId);
            session.clearMessages();
        });

        it("disable suggestion diagnostics", () => {
            const file: File = {
                path: "/a.js",
                content: 'require("b")',
            };

            const host = createServerHost([file]);
            const session = createSession(host, { canUseEvents: true });
            const service = session.getProjectService();

            session.executeCommandSeq<protocol.OpenRequest>({
                command: server.CommandNames.Open,
                arguments: { file: file.path, fileContent: file.content },
            });

            session.executeCommandSeq<protocol.ConfigureRequest>({
                command: server.CommandNames.Configure,
                arguments: {
                    preferences: { disableSuggestions: true }
                },
            });

            checkNumberOfProjects(service, { inferredProjects: 1 });
            session.clearMessages();
            const expectedSequenceId = session.getNextSeq();
            host.checkTimeoutQueueLengthAndRun(2);

            checkProjectUpdatedInBackgroundEvent(session, [file.path]);
            session.clearMessages();

            session.executeCommandSeq<protocol.GeterrRequest>({
                command: server.CommandNames.Geterr,
                arguments: {
                    delay: 0,
                    files: [file.path],
                }
            });

            host.checkTimeoutQueueLengthAndRun(1);

            checkErrorMessage(session, "syntaxDiag", { file: file.path, diagnostics: [] }, /*isMostRecent*/ true);
            session.clearMessages();

            host.runQueuedImmediateCallbacks(1);

            checkErrorMessage(session, "semanticDiag", { file: file.path, diagnostics: [] });
            // No suggestion event, we're done.
            checkCompleteEvent(session, 2, expectedSequenceId);
            session.clearMessages();
        });

        it("suppressed diagnostic events", () => {
            const file: File = {
                path: "/a.ts",
                content: "1 = 2;",
            };

            const host = createServerHost([file]);
            const session = createSession(host, { canUseEvents: true, suppressDiagnosticEvents: true });
            const service = session.getProjectService();

            session.executeCommandSeq<protocol.OpenRequest>({
                command: server.CommandNames.Open,
                arguments: { file: file.path, fileContent: file.content },
            });

            checkNumberOfProjects(service, { inferredProjects: 1 });

            host.checkTimeoutQueueLength(0);
            checkNoDiagnosticEvents(session);

            session.clearMessages();

            let expectedSequenceId = session.getNextSeq();

            session.executeCommandSeq<protocol.GeterrRequest>({
                command: server.CommandNames.Geterr,
                arguments: {
                    delay: 0,
                    files: [file.path],
                }
            });

            host.checkTimeoutQueueLength(0);
            checkNoDiagnosticEvents(session);

            checkCompleteEvent(session, 1, expectedSequenceId);

            session.clearMessages();

            expectedSequenceId = session.getNextSeq();

            session.executeCommandSeq<protocol.GeterrForProjectRequest>({
                command: server.CommandNames.Geterr,
                arguments: {
                    delay: 0,
                    file: file.path,
                }
            });

            host.checkTimeoutQueueLength(0);
            checkNoDiagnosticEvents(session);

            checkCompleteEvent(session, 1, expectedSequenceId);

            session.clearMessages();
        });
    });

    describe("tsserverProjectSystem Configure file diagnostics events", () => {

        it("are generated when the config file has errors", () => {
            const file = {
                path: "/a/b/app.ts",
                content: "let x = 10"
            };
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {
                        "foo": "bar",
                        "allowJS": true
                    }
                }`
            };
            const serverEventManager = new TestServerEventManager([file, configFile]);
            openFilesForSession([file], serverEventManager.session);
            serverEventManager.checkSingleConfigFileDiagEvent(configFile.path, file.path);
        });

        it("are generated when the config file doesn't have errors", () => {
            const file = {
                path: "/a/b/app.ts",
                content: "let x = 10"
            };
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {}
                }`
            };
            const serverEventManager = new TestServerEventManager([file, configFile]);
            openFilesForSession([file], serverEventManager.session);
            serverEventManager.checkSingleConfigFileDiagEvent(configFile.path, file.path);
        });

        it("are generated when the config file changes", () => {
            const file = {
                path: "/a/b/app.ts",
                content: "let x = 10"
            };
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {}
                }`
            };

            const serverEventManager = new TestServerEventManager([file, configFile]);
            openFilesForSession([file], serverEventManager.session);
            serverEventManager.checkSingleConfigFileDiagEvent(configFile.path, file.path);

            configFile.content = `{
                "compilerOptions": {
                    "haha": 123
                }
            }`;
            serverEventManager.host.reloadFS([file, configFile]);
            serverEventManager.host.runQueuedTimeoutCallbacks();
            serverEventManager.checkSingleConfigFileDiagEvent(configFile.path, configFile.path);

            configFile.content = `{
                "compilerOptions": {}
            }`;
            serverEventManager.host.reloadFS([file, configFile]);
            serverEventManager.host.runQueuedTimeoutCallbacks();
            serverEventManager.checkSingleConfigFileDiagEvent(configFile.path, configFile.path);
        });

        it("are not generated when the config file does not include file opened and config file has errors", () => {
            const file = {
                path: "/a/b/app.ts",
                content: "let x = 10"
            };
            const file2 = {
                path: "/a/b/test.ts",
                content: "let x = 10"
            };
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {
                        "foo": "bar",
                        "allowJS": true
                    },
                    "files": ["app.ts"]
                }`
            };
            const serverEventManager = new TestServerEventManager([file, file2, libFile, configFile]);
            openFilesForSession([file2], serverEventManager.session);
            serverEventManager.hasZeroEvent("configFileDiag");
        });

        it("are not generated when the config file has errors but suppressDiagnosticEvents is true", () => {
            const file = {
                path: "/a/b/app.ts",
                content: "let x = 10"
            };
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {
                        "foo": "bar",
                        "allowJS": true
                    }
                }`
            };
            const serverEventManager = new TestServerEventManager([file, configFile], /*suppressDiagnosticEvents*/ true);
            openFilesForSession([file], serverEventManager.session);
            serverEventManager.hasZeroEvent("configFileDiag");
        });

        it("are not generated when the config file does not include file opened and doesnt contain any errors", () => {
            const file = {
                path: "/a/b/app.ts",
                content: "let x = 10"
            };
            const file2 = {
                path: "/a/b/test.ts",
                content: "let x = 10"
            };
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "files": ["app.ts"]
                }`
            };

            const serverEventManager = new TestServerEventManager([file, file2, libFile, configFile]);
            openFilesForSession([file2], serverEventManager.session);
            serverEventManager.hasZeroEvent("configFileDiag");
        });
    });

    describe("tsserverProjectSystem skipLibCheck", () => {
        it("should be turned on for js-only inferred projects", () => {
            const file1 = {
                path: "/a/b/file1.js",
                content: `
                /// <reference path="file2.d.ts" />
                var x = 1;`
            };
            const file2 = {
                path: "/a/b/file2.d.ts",
                content: `
                interface T {
                    name: string;
                };
                interface T {
                    name: number;
                };`
            };
            const host = createServerHost([file1, file2]);
            const session = createSession(host);
            openFilesForSession([file1, file2], session);

            const file2GetErrRequest = makeSessionRequest<protocol.SemanticDiagnosticsSyncRequestArgs>(
                CommandNames.SemanticDiagnosticsSync,
                { file: file2.path }
            );
            let errorResult = <protocol.Diagnostic[]>session.executeCommand(file2GetErrRequest).response;
            assert.isTrue(errorResult.length === 0);

            const closeFileRequest = makeSessionRequest<protocol.FileRequestArgs>(CommandNames.Close, { file: file1.path });
            session.executeCommand(closeFileRequest);
            errorResult = <protocol.Diagnostic[]>session.executeCommand(file2GetErrRequest).response;
            assert.isTrue(errorResult.length !== 0);

            openFilesForSession([file1], session);
            errorResult = <protocol.Diagnostic[]>session.executeCommand(file2GetErrRequest).response;
            assert.isTrue(errorResult.length === 0);
        });

        it("should be turned on for js-only external projects", () => {
            const jsFile = {
                path: "/a/b/file1.js",
                content: "let x =1;"
            };
            const dTsFile = {
                path: "/a/b/file2.d.ts",
                content: `
                interface T {
                    name: string;
                };
                interface T {
                    name: number;
                };`
            };
            const host = createServerHost([jsFile, dTsFile]);
            const session = createSession(host);

            const openExternalProjectRequest = makeSessionRequest<protocol.OpenExternalProjectArgs>(
                CommandNames.OpenExternalProject,
                {
                    projectFileName: "project1",
                    rootFiles: toExternalFiles([jsFile.path, dTsFile.path]),
                    options: {}
                }
            );
            session.executeCommand(openExternalProjectRequest);

            const dTsFileGetErrRequest = makeSessionRequest<protocol.SemanticDiagnosticsSyncRequestArgs>(
                CommandNames.SemanticDiagnosticsSync,
                { file: dTsFile.path }
            );
            const errorResult = <protocol.Diagnostic[]>session.executeCommand(dTsFileGetErrRequest).response;
            assert.isTrue(errorResult.length === 0);
        });

        it("should be turned on for js-only external projects with skipLibCheck=false", () => {
            const jsFile = {
                path: "/a/b/file1.js",
                content: "let x =1;"
            };
            const dTsFile = {
                path: "/a/b/file2.d.ts",
                content: `
                interface T {
                    name: string;
                };
                interface T {
                    name: number;
                };`
            };
            const host = createServerHost([jsFile, dTsFile]);
            const session = createSession(host);

            const openExternalProjectRequest = makeSessionRequest<protocol.OpenExternalProjectArgs>(
                CommandNames.OpenExternalProject,
                {
                    projectFileName: "project1",
                    rootFiles: toExternalFiles([jsFile.path, dTsFile.path]),
                    options: { skipLibCheck: false }
                }
            );
            session.executeCommand(openExternalProjectRequest);

            const dTsFileGetErrRequest = makeSessionRequest<protocol.SemanticDiagnosticsSyncRequestArgs>(
                CommandNames.SemanticDiagnosticsSync,
                { file: dTsFile.path }
            );
            const errorResult = <protocol.Diagnostic[]>session.executeCommand(dTsFileGetErrRequest).response;
            assert.isTrue(errorResult.length === 0);
        });

        it("should not report bind errors for declaration files with skipLibCheck=true", () => {
            const jsconfigFile = {
                path: "/a/jsconfig.json",
                content: "{}"
            };
            const jsFile = {
                path: "/a/jsFile.js",
                content: "let x = 1;"
            };
            const dTsFile1 = {
                path: "/a/dTsFile1.d.ts",
                content: `
                declare var x: number;`
            };
            const dTsFile2 = {
                path: "/a/dTsFile2.d.ts",
                content: `
                declare var x: string;`
            };
            const host = createServerHost([jsconfigFile, jsFile, dTsFile1, dTsFile2]);
            const session = createSession(host);
            openFilesForSession([jsFile], session);

            const dTsFile1GetErrRequest = makeSessionRequest<protocol.SemanticDiagnosticsSyncRequestArgs>(
                CommandNames.SemanticDiagnosticsSync,
                { file: dTsFile1.path }
            );
            const error1Result = <protocol.Diagnostic[]>session.executeCommand(dTsFile1GetErrRequest).response;
            assert.isTrue(error1Result.length === 0);

            const dTsFile2GetErrRequest = makeSessionRequest<protocol.SemanticDiagnosticsSyncRequestArgs>(
                CommandNames.SemanticDiagnosticsSync,
                { file: dTsFile2.path }
            );
            const error2Result = <protocol.Diagnostic[]>session.executeCommand(dTsFile2GetErrRequest).response;
            assert.isTrue(error2Result.length === 0);
        });

        it("should report semantic errors for loose JS files with '// @ts-check' and skipLibCheck=true", () => {
            const jsFile = {
                path: "/a/jsFile.js",
                content: `
                // @ts-check
                let x = 1;
                x === "string";`
            };

            const host = createServerHost([jsFile]);
            const session = createSession(host);
            openFilesForSession([jsFile], session);

            const getErrRequest = makeSessionRequest<protocol.SemanticDiagnosticsSyncRequestArgs>(
                CommandNames.SemanticDiagnosticsSync,
                { file: jsFile.path }
            );
            const errorResult = <protocol.Diagnostic[]>session.executeCommand(getErrRequest).response;
            assert.isTrue(errorResult.length === 1);
            assert.equal(errorResult[0].code, Diagnostics.This_condition_will_always_return_0_since_the_types_1_and_2_have_no_overlap.code);
        });

        it("should report semantic errors for configured js project with '// @ts-check' and skipLibCheck=true", () => {
            const jsconfigFile = {
                path: "/a/jsconfig.json",
                content: "{}"
            };

            const jsFile = {
                path: "/a/jsFile.js",
                content: `
                // @ts-check
                let x = 1;
                x === "string";`
            };

            const host = createServerHost([jsconfigFile, jsFile]);
            const session = createSession(host);
            openFilesForSession([jsFile], session);

            const getErrRequest = makeSessionRequest<protocol.SemanticDiagnosticsSyncRequestArgs>(
                CommandNames.SemanticDiagnosticsSync,
                { file: jsFile.path }
            );
            const errorResult = <protocol.Diagnostic[]>session.executeCommand(getErrRequest).response;
            assert.isTrue(errorResult.length === 1);
            assert.equal(errorResult[0].code, Diagnostics.This_condition_will_always_return_0_since_the_types_1_and_2_have_no_overlap.code);
        });

        it("should report semantic errors for configured js project with checkJs=true and skipLibCheck=true", () => {
            const jsconfigFile = {
                path: "/a/jsconfig.json",
                content: JSON.stringify({
                    compilerOptions: {
                        checkJs: true,
                        skipLibCheck: true
                    },
                })
            };
            const jsFile = {
                path: "/a/jsFile.js",
                content: `let x = 1;
                x === "string";`
            };

            const host = createServerHost([jsconfigFile, jsFile]);
            const session = createSession(host);
            openFilesForSession([jsFile], session);

            const getErrRequest = makeSessionRequest<protocol.SemanticDiagnosticsSyncRequestArgs>(
                CommandNames.SemanticDiagnosticsSync,
                { file: jsFile.path }
            );
            const errorResult = <protocol.Diagnostic[]>session.executeCommand(getErrRequest).response;
            assert.isTrue(errorResult.length === 1);
            assert.equal(errorResult[0].code, Diagnostics.This_condition_will_always_return_0_since_the_types_1_and_2_have_no_overlap.code);
        });
    });

    describe("tsserverProjectSystem non-existing directories listed in config file input array", () => {
        it("should be tolerated without crashing the server", () => {
            const configFile = {
                path: "/a/b/tsconfig.json",
                content: `{
                    "compilerOptions": {},
                    "include": ["app/*", "test/**/*", "something"]
                }`
            };
            const file1 = {
                path: "/a/b/file1.ts",
                content: "let t = 10;"
            };

            const host = createServerHost([file1, configFile]);
            const projectService = createProjectService(host);
            projectService.openClientFile(file1.path);
            host.runQueuedTimeoutCallbacks();
            // Since there is no file open from configFile it would be closed
            checkNumberOfConfiguredProjects(projectService, 0);
            checkNumberOfInferredProjects(projectService, 1);

            const inferredProject = projectService.inferredProjects[0];
            assert.isTrue(inferredProject.containsFile(<server.NormalizedPath>file1.path));
        });

        it("should be able to handle @types if input file list is empty", () => {
            const f = {
                path: "/a/app.ts",
                content: "let x = 1"
            };
            const config = {
                path: "/a/tsconfig.json",
                content: JSON.stringify({
                    compiler: {},
                    files: []
                })
            };
            const t1 = {
                path: "/a/node_modules/@types/typings/index.d.ts",
                content: `export * from "./lib"`
            };
            const t2 = {
                path: "/a/node_modules/@types/typings/lib.d.ts",
                content: `export const x: number`
            };
            const host = createServerHost([f, config, t1, t2], { currentDirectory: getDirectoryPath(f.path) });
            const projectService = createProjectService(host);

            projectService.openClientFile(f.path);
            // Since no file from the configured project is open, it would be closed immediately
            projectService.checkNumberOfProjects({ configuredProjects: 0, inferredProjects: 1 });
        });

        it("should tolerate invalid include files that start in subDirectory", () => {
            const projectFolder = "/user/username/projects/myproject";
            const f = {
                path: `${projectFolder}/src/server/index.ts`,
                content: "let x = 1"
            };
            const config = {
                path: `${projectFolder}/src/server/tsconfig.json`,
                content: JSON.stringify({
                    compiler: {
                        module: "commonjs",
                        outDir: "../../build"
                    },
                    include: [
                        "../src/**/*.ts"
                    ]
                })
            };
            const host = createServerHost([f, config, libFile], { useCaseSensitiveFileNames: true });
            const projectService = createProjectService(host);

            projectService.openClientFile(f.path);
            // Since no file from the configured project is open, it would be closed immediately
            projectService.checkNumberOfProjects({ configuredProjects: 0, inferredProjects: 1 });
        });
    });

    describe("tsserverProjectSystem reload", () => {
        it("should work with temp file", () => {
            const f1 = {
                path: "/a/b/app.ts",
                content: "let x = 1"
            };
            const tmp = {
                path: "/a/b/app.tmp",
                content: "const y = 42"
            };
            const host = createServerHost([f1, tmp]);
            const session = createSession(host);

            // send open request
            session.executeCommand(<server.protocol.OpenRequest>{
                type: "request",
                command: "open",
                seq: 1,
                arguments: { file: f1.path }
            });

            // reload from tmp file
            session.executeCommand(<server.protocol.ReloadRequest>{
                type: "request",
                command: "reload",
                seq: 2,
                arguments: { file: f1.path, tmpfile: tmp.path }
            });

            // verify content
            const projectServiice = session.getProjectService();
            const snap1 = projectServiice.getScriptInfo(f1.path)!.getSnapshot();
            assert.equal(getSnapshotText(snap1), tmp.content, "content should be equal to the content of temp file");

            // reload from original file file
            session.executeCommand(<server.protocol.ReloadRequest>{
                type: "request",
                command: "reload",
                seq: 2,
                arguments: { file: f1.path }
            });

            // verify content
            const snap2 = projectServiice.getScriptInfo(f1.path)!.getSnapshot();
            assert.equal(getSnapshotText(snap2), f1.content, "content should be equal to the content of original file");

        });

        it("should work when script info doesnt have any project open", () => {
            const f1 = {
                path: "/a/b/app.ts",
                content: "let x = 1"
            };
            const tmp = {
                path: "/a/b/app.tmp",
                content: "const y = 42"
            };
            const host = createServerHost([f1, tmp, libFile]);
            const session = createSession(host);
            const openContent = "let z = 1";
            // send open request
            session.executeCommandSeq(<server.protocol.OpenRequest>{
                command: server.protocol.CommandTypes.Open,
                arguments: { file: f1.path, fileContent: openContent }
            });

            const projectService = session.getProjectService();
            checkNumberOfProjects(projectService, { inferredProjects: 1 });
            const info = projectService.getScriptInfo(f1.path)!;
            assert.isDefined(info);
            checkScriptInfoContents(openContent, "contents set during open request");

            // send close request
            session.executeCommandSeq(<server.protocol.CloseRequest>{
                command: server.protocol.CommandTypes.Close,
                arguments: { file: f1.path }
            });
            checkScriptInfoAndProjects(f1.content, "contents of closed file");
            checkInferredProjectIsOrphan();

            // Can reload contents of the file when its not open and has no project
            // reload from temp file
            session.executeCommandSeq(<server.protocol.ReloadRequest>{
                command: server.protocol.CommandTypes.Reload,
                arguments: { file: f1.path, tmpfile: tmp.path }
            });
            checkScriptInfoAndProjects(tmp.content, "contents of temp file");
            checkInferredProjectIsOrphan();

            // reload from own file
            session.executeCommandSeq(<server.protocol.ReloadRequest>{
                command: server.protocol.CommandTypes.Reload,
                arguments: { file: f1.path }
            });
            checkScriptInfoAndProjects(f1.content, "contents of closed file");
            checkInferredProjectIsOrphan();

            // Open file again without setting its content
            session.executeCommandSeq(<server.protocol.OpenRequest>{
                command: server.protocol.CommandTypes.Open,
                arguments: { file: f1.path }
            });
            checkScriptInfoAndProjects(f1.content, "contents of file when opened without specifying contents");
            const snap = info.getSnapshot();

            // send close request
            session.executeCommandSeq(<server.protocol.CloseRequest>{
                command: server.protocol.CommandTypes.Close,
                arguments: { file: f1.path }
            });
            checkScriptInfoAndProjects(f1.content, "contents of closed file");
            assert.strictEqual(info.getSnapshot(), snap);
            checkInferredProjectIsOrphan();

            // reload from temp file
            session.executeCommandSeq(<server.protocol.ReloadRequest>{
                command: server.protocol.CommandTypes.Reload,
                arguments: { file: f1.path, tmpfile: tmp.path }
            });
            checkScriptInfoAndProjects(tmp.content, "contents of temp file");
            assert.notStrictEqual(info.getSnapshot(), snap);
            checkInferredProjectIsOrphan();

            // reload from own file
            session.executeCommandSeq(<server.protocol.ReloadRequest>{
                command: server.protocol.CommandTypes.Reload,
                arguments: { file: f1.path }
            });
            checkScriptInfoAndProjects(f1.content, "contents of closed file");
            assert.notStrictEqual(info.getSnapshot(), snap);
            checkInferredProjectIsOrphan();

            function checkInferredProjectIsOrphan() {
                assert.isTrue(projectService.inferredProjects[0].isOrphan());
                assert.equal(info.containingProjects.length, 0);
            }

            function checkScriptInfoAndProjects(contentsOfInfo: string, captionForContents: string) {
                checkNumberOfProjects(projectService, { inferredProjects: 1 });
                assert.strictEqual(projectService.getScriptInfo(f1.path), info);
                checkScriptInfoContents(contentsOfInfo, captionForContents);
            }

            function checkScriptInfoContents(contentsOfInfo: string, captionForContents: string) {
                const snap = info.getSnapshot();
                assert.equal(getSnapshotText(snap), contentsOfInfo, "content should be equal to " + captionForContents);
            }
        });
    });

    describe("tsserverProjectSystem Inferred projects", () => {
        it("should support files without extensions", () => {
            const f = {
                path: "/a/compile",
                content: "let x = 1"
            };
            const host = createServerHost([f]);
            const session = createSession(host);
            session.executeCommand(<server.protocol.SetCompilerOptionsForInferredProjectsRequest>{
                seq: 1,
                type: "request",
                command: "compilerOptionsForInferredProjects",
                arguments: {
                    options: {
                        allowJs: true
                    }
                }
            });
            session.executeCommand(<server.protocol.OpenRequest>{
                seq: 2,
                type: "request",
                command: "open",
                arguments: {
                    file: f.path,
                    fileContent: f.content,
                    scriptKindName: "JS"
                }
            });
            const projectService = session.getProjectService();
            checkNumberOfProjects(projectService, { inferredProjects: 1 });
            checkProjectActualFiles(projectService.inferredProjects[0], [f.path]);
        });

        it("inferred projects per project root", () => {
            const file1 = { path: "/a/file1.ts", content: "let x = 1;", projectRootPath: "/a" };
            const file2 = { path: "/a/file2.ts", content: "let y = 2;", projectRootPath: "/a" };
            const file3 = { path: "/b/file2.ts", content: "let x = 3;", projectRootPath: "/b" };
            const file4 = { path: "/c/file3.ts", content: "let z = 4;" };
            const host = createServerHost([file1, file2, file3, file4]);
            const session = createSession(host, {
                useSingleInferredProject: true,
                useInferredProjectPerProjectRoot: true
            });
            session.executeCommand(<server.protocol.SetCompilerOptionsForInferredProjectsRequest>{
                seq: 1,
                type: "request",
                command: CommandNames.CompilerOptionsForInferredProjects,
                arguments: {
                    options: {
                        allowJs: true,
                        target: ScriptTarget.ESNext
                    }
                }
            });
            session.executeCommand(<server.protocol.SetCompilerOptionsForInferredProjectsRequest>{
                seq: 2,
                type: "request",
                command: CommandNames.CompilerOptionsForInferredProjects,
                arguments: {
                    options: {
                        allowJs: true,
                        target: ScriptTarget.ES2015
                    },
                    projectRootPath: "/b"
                }
            });
            session.executeCommand(<server.protocol.OpenRequest>{
                seq: 3,
                type: "request",
                command: CommandNames.Open,
                arguments: {
                    file: file1.path,
                    fileContent: file1.content,
                    scriptKindName: "JS",
                    projectRootPath: file1.projectRootPath
                }
            });
            session.executeCommand(<server.protocol.OpenRequest>{
                seq: 4,
                type: "request",
                command: CommandNames.Open,
                arguments: {
                    file: file2.path,
                    fileContent: file2.content,
                    scriptKindName: "JS",
                    projectRootPath: file2.projectRootPath
                }
            });
            session.executeCommand(<server.protocol.OpenRequest>{
                seq: 5,
                type: "request",
                command: CommandNames.Open,
                arguments: {
                    file: file3.path,
                    fileContent: file3.content,
                    scriptKindName: "JS",
                    projectRootPath: file3.projectRootPath
                }
            });
            session.executeCommand(<server.protocol.OpenRequest>{
                seq: 6,
                type: "request",
                command: CommandNames.Open,
                arguments: {
                    file: file4.path,
                    fileContent: file4.content,
                    scriptKindName: "JS"
                }
            });

            const projectService = session.getProjectService();
            checkNumberOfProjects(projectService, { inferredProjects: 3 });
            checkProjectActualFiles(projectService.inferredProjects[0], [file4.path]);
            checkProjectActualFiles(projectService.inferredProjects[1], [file1.path, file2.path]);
            checkProjectActualFiles(projectService.inferredProjects[2], [file3.path]);
            assert.equal(projectService.inferredProjects[0].getCompilationSettings().target, ScriptTarget.ESNext);
            assert.equal(projectService.inferredProjects[1].getCompilationSettings().target, ScriptTarget.ESNext);
            assert.equal(projectService.inferredProjects[2].getCompilationSettings().target, ScriptTarget.ES2015);
        });

        function checkInferredProject(inferredProject: server.InferredProject, actualFiles: File[], target: ScriptTarget) {
            checkProjectActualFiles(inferredProject, actualFiles.map(f => f.path));
            assert.equal(inferredProject.getCompilationSettings().target, target);
        }

        function verifyProjectRootWithCaseSensitivity(useCaseSensitiveFileNames: boolean) {
            const files: [File, File, File, File] = [
                { path: "/a/file1.ts", content: "let x = 1;" },
                { path: "/A/file2.ts", content: "let y = 2;" },
                { path: "/b/file2.ts", content: "let x = 3;" },
                { path: "/c/file3.ts", content: "let z = 4;" }
            ];
            const host = createServerHost(files, { useCaseSensitiveFileNames });
            const projectService = createProjectService(host, { useSingleInferredProject: true, }, { useInferredProjectPerProjectRoot: true });
            projectService.setCompilerOptionsForInferredProjects({
                allowJs: true,
                target: ScriptTarget.ESNext
            });
            projectService.setCompilerOptionsForInferredProjects({
                allowJs: true,
                target: ScriptTarget.ES2015
            }, "/a");

            openClientFiles(["/a", "/a", "/b", undefined]);
            verifyInferredProjectsState([
                [[files[3]], ScriptTarget.ESNext],
                [[files[0], files[1]], ScriptTarget.ES2015],
                [[files[2]], ScriptTarget.ESNext]
            ]);
            closeClientFiles();

            openClientFiles(["/a", "/A", "/b", undefined]);
            if (useCaseSensitiveFileNames) {
                verifyInferredProjectsState([
                    [[files[3]], ScriptTarget.ESNext],
                    [[files[0]], ScriptTarget.ES2015],
                    [[files[1]], ScriptTarget.ESNext],
                    [[files[2]], ScriptTarget.ESNext]
                ]);
            }
            else {
                verifyInferredProjectsState([
                    [[files[3]], ScriptTarget.ESNext],
                    [[files[0], files[1]], ScriptTarget.ES2015],
                    [[files[2]], ScriptTarget.ESNext]
                ]);
            }
            closeClientFiles();

            projectService.setCompilerOptionsForInferredProjects({
                allowJs: true,
                target: ScriptTarget.ES2017
            }, "/A");

            openClientFiles(["/a", "/a", "/b", undefined]);
            verifyInferredProjectsState([
                [[files[3]], ScriptTarget.ESNext],
                [[files[0], files[1]], useCaseSensitiveFileNames ? ScriptTarget.ES2015 : ScriptTarget.ES2017],
                [[files[2]], ScriptTarget.ESNext]
            ]);
            closeClientFiles();

            openClientFiles(["/a", "/A", "/b", undefined]);
            if (useCaseSensitiveFileNames) {
                verifyInferredProjectsState([
                    [[files[3]], ScriptTarget.ESNext],
                    [[files[0]], ScriptTarget.ES2015],
                    [[files[1]], ScriptTarget.ES2017],
                    [[files[2]], ScriptTarget.ESNext]
                ]);
            }
            else {
                verifyInferredProjectsState([
                    [[files[3]], ScriptTarget.ESNext],
                    [[files[0], files[1]], ScriptTarget.ES2017],
                    [[files[2]], ScriptTarget.ESNext]
                ]);
            }
            closeClientFiles();

            function openClientFiles(projectRoots: [string | undefined, string | undefined, string | undefined, string | undefined]) {
                files.forEach((file, index) => {
                    projectService.openClientFile(file.path, file.content, ScriptKind.JS, projectRoots[index]);
                });
            }

            function closeClientFiles() {
                files.forEach(file => projectService.closeClientFile(file.path));
            }

            function verifyInferredProjectsState(expected: [File[], ScriptTarget][]) {
                checkNumberOfProjects(projectService, { inferredProjects: expected.length });
                projectService.inferredProjects.forEach((p, index) => {
                    const [actualFiles, target] = expected[index];
                    checkInferredProject(p, actualFiles, target);
                });
            }
        }

        it("inferred projects per project root with case sensitive system", () => {
            verifyProjectRootWithCaseSensitivity(/*useCaseSensitiveFileNames*/ true);
        });

        it("inferred projects per project root with case insensitive system", () => {
            verifyProjectRootWithCaseSensitivity(/*useCaseSensitiveFileNames*/ false);
        });
    });

    describe("tsserverProjectSystem No overwrite emit error", () => {
        it("for inferred project", () => {
            const f1 = {
                path: "/a/b/f1.js",
                content: "function test1() { }"
            };
            const host = createServerHost([f1, libFile]);
            const session = createSession(host);
            openFilesForSession([f1], session);

            const projectService = session.getProjectService();
            checkNumberOfProjects(projectService, { inferredProjects: 1 });
            const projectName = projectService.inferredProjects[0].getProjectName();

            const diags = session.executeCommand(<server.protocol.CompilerOptionsDiagnosticsRequest>{
                type: "request",
                command: server.CommandNames.CompilerOptionsDiagnosticsFull,
                seq: 2,
                arguments: { projectFileName: projectName }
            }).response as ReadonlyArray<protocol.DiagnosticWithLinePosition>;
            assert.isTrue(diags.length === 0);

            session.executeCommand(<server.protocol.SetCompilerOptionsForInferredProjectsRequest>{
                type: "request",
                command: server.CommandNames.CompilerOptionsForInferredProjects,
                seq: 3,
                arguments: { options: { module: ModuleKind.CommonJS } }
            });
            const diagsAfterUpdate = session.executeCommand(<server.protocol.CompilerOptionsDiagnosticsRequest>{
                type: "request",
                command: server.CommandNames.CompilerOptionsDiagnosticsFull,
                seq: 4,
                arguments: { projectFileName: projectName }
            }).response as ReadonlyArray<protocol.DiagnosticWithLinePosition>;
            assert.isTrue(diagsAfterUpdate.length === 0);
        });

        it("for external project", () => {
            const f1 = {
                path: "/a/b/f1.js",
                content: "function test1() { }"
            };
            const host = createServerHost([f1, libFile]);
            const session = createSession(host);
            const projectService = session.getProjectService();
            const projectFileName = "/a/b/project.csproj";
            const externalFiles = toExternalFiles([f1.path]);
            projectService.openExternalProject(<protocol.ExternalProject>{
                projectFileName,
                rootFiles: externalFiles,
                options: {}
            });

            checkNumberOfProjects(projectService, { externalProjects: 1 });

            const diags = session.executeCommand(<server.protocol.CompilerOptionsDiagnosticsRequest>{
                type: "request",
                command: server.CommandNames.CompilerOptionsDiagnosticsFull,
                seq: 2,
                arguments: { projectFileName }
            }).response as ReadonlyArray<server.protocol.DiagnosticWithLinePosition>;
            assert.isTrue(diags.length === 0);

            session.executeCommand(<server.protocol.OpenExternalProjectRequest>{
                type: "request",
                command: server.CommandNames.OpenExternalProject,
                seq: 3,
                arguments: {
                    projectFileName,
                    rootFiles: externalFiles,
                    options: { module: ModuleKind.CommonJS }
                }
            });
            const diagsAfterUpdate = session.executeCommand(<server.protocol.CompilerOptionsDiagnosticsRequest>{
                type: "request",
                command: server.CommandNames.CompilerOptionsDiagnosticsFull,
                seq: 4,
                arguments: { projectFileName }
            }).response as ReadonlyArray<server.protocol.DiagnosticWithLinePosition>;
            assert.isTrue(diagsAfterUpdate.length === 0);
        });
    });

    describe("tsserverProjectSystem emit with outFile or out setting", () => {
        function test(opts: CompilerOptions, expectedUsesOutFile: boolean) {
            const f1 = {
                path: "/a/a.ts",
                content: "let x = 1"
            };
            const f2 = {
                path: "/a/b.ts",
                content: "let y = 1"
            };
            const config = {
                path: "/a/tsconfig.json",
                content: JSON.stringify({
                    compilerOptions: opts,
                    compileOnSave: true
                })
            };
            const host = createServerHost([f1, f2, config]);
            const session = createSession(host);
            session.executeCommand(<protocol.OpenRequest>{
                seq: 1,
                type: "request",
                command: "open",
                arguments: { file: f1.path }
            });
            checkNumberOfProjects(session.getProjectService(), { configuredProjects: 1 });
            const { response } = session.executeCommand(<protocol.CompileOnSaveAffectedFileListRequest>{
                seq: 2,
                type: "request",
                command: "compileOnSaveAffectedFileList",
                arguments: { file: f1.path }
            });
            assert.equal((<protocol.CompileOnSaveAffectedFileListSingleProject[]>response).length, 1, "expected output for 1 project");
            assert.equal((<protocol.CompileOnSaveAffectedFileListSingleProject[]>response)[0].fileNames.length, 2, "expected output for 1 project");
            assert.equal((<protocol.CompileOnSaveAffectedFileListSingleProject[]>response)[0].projectUsesOutFile, expectedUsesOutFile, "usesOutFile");
        }

        it("projectUsesOutFile should not be returned if not set", () => {
            test({}, /*expectedUsesOutFile*/ false);
        });
        it("projectUsesOutFile should be true if outFile is set", () => {
            test({ outFile: "/a/out.js" }, /*expectedUsesOutFile*/ true);
        });
        it("projectUsesOutFile should be true if out is set", () => {
            test({ out: "/a/out.js" }, /*expectedUsesOutFile*/ true);
        });
    });

    describe("tsserverProjectSystem import helpers", () => {
        it("should not crash in tsserver", () => {
            const f1 = {
                path: "/a/app.ts",
                content: "export async function foo() { return 100; }"
            };
            const tslib = {
                path: "/a/node_modules/tslib/index.d.ts",
                content: ""
            };
            const host = createServerHost([f1, tslib]);
            const service = createProjectService(host);
            service.openExternalProject({ projectFileName: "p", rootFiles: [toExternalFile(f1.path)], options: { importHelpers: true } });
            service.checkNumberOfProjects({ externalProjects: 1 });
        });
    });

    describe("tsserverProjectSystem searching for config file", () => {
        it("should stop at projectRootPath if given", () => {
            const f1 = {
                path: "/a/file1.ts",
                content: ""
            };
            const configFile = {
                path: "/tsconfig.json",
                content: "{}"
            };
            const host = createServerHost([f1, configFile]);
            const service = createProjectService(host);
            service.openClientFile(f1.path, /*fileContent*/ undefined, /*scriptKind*/ undefined, "/a");

            checkNumberOfConfiguredProjects(service, 0);
            checkNumberOfInferredProjects(service, 1);

            service.closeClientFile(f1.path);
            service.openClientFile(f1.path);
            checkNumberOfConfiguredProjects(service, 1);
            checkNumberOfInferredProjects(service, 0);
        });

        it("should use projectRootPath when searching for inferred project again", () => {
            const projectDir = "/a/b/projects/project";
            const configFileLocation = `${projectDir}/src`;
            const f1 = {
                path: `${configFileLocation}/file1.ts`,
                content: ""
            };
            const configFile = {
                path: `${configFileLocation}/tsconfig.json`,
                content: "{}"
            };
            const configFile2 = {
                path: "/a/b/projects/tsconfig.json",
                content: "{}"
            };
            const host = createServerHost([f1, libFile, configFile, configFile2]);
            const service = createProjectService(host);
            service.openClientFile(f1.path, /*fileContent*/ undefined, /*scriptKind*/ undefined, projectDir);
            checkNumberOfProjects(service, { configuredProjects: 1 });
            assert.isDefined(service.configuredProjects.get(configFile.path));
            checkWatchedFiles(host, [libFile.path, configFile.path]);
            checkWatchedDirectories(host, [], /*recursive*/ false);
            const typeRootLocations = getTypeRootsFromLocation(configFileLocation);
            checkWatchedDirectories(host, typeRootLocations.concat(configFileLocation), /*recursive*/ true);

            // Delete config file - should create inferred project and not configured project
            host.reloadFS([f1, libFile, configFile2]);
            host.runQueuedTimeoutCallbacks();
            checkNumberOfProjects(service, { inferredProjects: 1 });
            checkWatchedFiles(host, [libFile.path, configFile.path, `${configFileLocation}/jsconfig.json`, `${projectDir}/tsconfig.json`, `${projectDir}/jsconfig.json`]);
            checkWatchedDirectories(host, [], /*recursive*/ false);
            checkWatchedDirectories(host, typeRootLocations, /*recursive*/ true);
        });

        it("should use projectRootPath when searching for inferred project again 2", () => {
            const projectDir = "/a/b/projects/project";
            const configFileLocation = `${projectDir}/src`;
            const f1 = {
                path: `${configFileLocation}/file1.ts`,
                content: ""
            };
            const configFile = {
                path: `${configFileLocation}/tsconfig.json`,
                content: "{}"
            };
            const configFile2 = {
                path: "/a/b/projects/tsconfig.json",
                content: "{}"
            };
            const host = createServerHost([f1, libFile, configFile, configFile2]);
            const service = createProjectService(host, { useSingleInferredProject: true }, { useInferredProjectPerProjectRoot: true });
            service.openClientFile(f1.path, /*fileContent*/ undefined, /*scriptKind*/ undefined, projectDir);
            checkNumberOfProjects(service, { configuredProjects: 1 });
            assert.isDefined(service.configuredProjects.get(configFile.path));
            checkWatchedFiles(host, [libFile.path, configFile.path]);
            checkWatchedDirectories(host, [], /*recursive*/ false);
            checkWatchedDirectories(host, getTypeRootsFromLocation(configFileLocation).concat(configFileLocation), /*recursive*/ true);

            // Delete config file - should create inferred project with project root path set
            host.reloadFS([f1, libFile, configFile2]);
            host.runQueuedTimeoutCallbacks();
            checkNumberOfProjects(service, { inferredProjects: 1 });
            assert.equal(service.inferredProjects[0].projectRootPath, projectDir);
            checkWatchedFiles(host, [libFile.path, configFile.path, `${configFileLocation}/jsconfig.json`, `${projectDir}/tsconfig.json`, `${projectDir}/jsconfig.json`]);
            checkWatchedDirectories(host, [], /*recursive*/ false);
            checkWatchedDirectories(host, getTypeRootsFromLocation(projectDir), /*recursive*/ true);
        });

        describe("when the opened file is not from project root", () => {
            const projectRoot = "/a/b/projects/project";
            const file: File = {
                path: `${projectRoot}/src/index.ts`,
                content: "let y = 10"
            };
            const tsconfig: File = {
                path: `${projectRoot}/tsconfig.json`,
                content: "{}"
            };
            const files = [file, libFile];
            const filesWithConfig = files.concat(tsconfig);
            const dirOfFile = getDirectoryPath(file.path);

            function openClientFile(files: File[]) {
                const host = createServerHost(files);
                const projectService = createProjectService(host);

                projectService.openClientFile(file.path, /*fileContent*/ undefined, /*scriptKind*/ undefined, "/a/b/projects/proj");
                return { host, projectService };
            }

            function verifyConfiguredProject(host: TestServerHost, projectService: TestProjectService, orphanInferredProject?: boolean) {
                projectService.checkNumberOfProjects({ configuredProjects: 1, inferredProjects: orphanInferredProject ? 1 : 0 });
                const project = Debug.assertDefined(projectService.configuredProjects.get(tsconfig.path));

                if (orphanInferredProject) {
                    const inferredProject = projectService.inferredProjects[0];
                    assert.isTrue(inferredProject.isOrphan());
                }

                checkProjectActualFiles(project, [file.path, libFile.path, tsconfig.path]);
                checkWatchedFiles(host, [libFile.path, tsconfig.path]);
                checkWatchedDirectories(host, emptyArray, /*recursive*/ false);
                checkWatchedDirectories(host, (orphanInferredProject ? [projectRoot, `${dirOfFile}/node_modules/@types`] : [projectRoot]).concat(getTypeRootsFromLocation(projectRoot)), /*recursive*/ true);
            }

            function verifyInferredProject(host: TestServerHost, projectService: TestProjectService) {
                projectService.checkNumberOfProjects({ inferredProjects: 1 });
                const project = projectService.inferredProjects[0];
                assert.isDefined(project);

                const filesToWatch = [libFile.path];
                forEachAncestorDirectory(dirOfFile, ancestor => {
                    filesToWatch.push(combinePaths(ancestor, "tsconfig.json"));
                    filesToWatch.push(combinePaths(ancestor, "jsconfig.json"));
                });

                checkProjectActualFiles(project, [file.path, libFile.path]);
                checkWatchedFiles(host, filesToWatch);
                checkWatchedDirectories(host, emptyArray, /*recursive*/ false);
                checkWatchedDirectories(host, getTypeRootsFromLocation(dirOfFile), /*recursive*/ true);
            }

            it("tsconfig for the file exists", () => {
                const { host, projectService } = openClientFile(filesWithConfig);
                verifyConfiguredProject(host, projectService);

                host.reloadFS(files);
                host.runQueuedTimeoutCallbacks();
                verifyInferredProject(host, projectService);

                host.reloadFS(filesWithConfig);
                host.runQueuedTimeoutCallbacks();
                verifyConfiguredProject(host, projectService, /*orphanInferredProject*/ true);
            });

            it("tsconfig for the file does not exist", () => {
                const { host, projectService } = openClientFile(files);
                verifyInferredProject(host, projectService);

                host.reloadFS(filesWithConfig);
                host.runQueuedTimeoutCallbacks();
                verifyConfiguredProject(host, projectService, /*orphanInferredProject*/ true);

                host.reloadFS(files);
                host.runQueuedTimeoutCallbacks();
                verifyInferredProject(host, projectService);
            });
        });
    });

    describe("tsserverProjectSystem cancellationToken", () => {
        // Disable sourcemap support for the duration of the test, as sourcemapping the errors generated during this test is slow and not something we care to test
        let oldPrepare: AnyFunction;
        before(() => {
            oldPrepare = (Error as any).prepareStackTrace;
            delete (Error as any).prepareStackTrace;
        });

        after(() => {
            (Error as any).prepareStackTrace = oldPrepare;
        });

        it("is attached to request", () => {
            const f1 = {
                path: "/a/b/app.ts",
                content: "let xyz = 1;"
            };
            const host = createServerHost([f1]);
            let expectedRequestId: number;
            const cancellationToken: server.ServerCancellationToken = {
                isCancellationRequested: () => false,
                setRequest: requestId => {
                    if (expectedRequestId === undefined) {
                        assert.isTrue(false, "unexpected call");
                    }
                    assert.equal(requestId, expectedRequestId);
                },
                resetRequest: noop
            };

            const session = createSession(host, { cancellationToken });

            expectedRequestId = session.getNextSeq();
            session.executeCommandSeq(<server.protocol.OpenRequest>{
                command: "open",
                arguments: { file: f1.path }
            });

            expectedRequestId = session.getNextSeq();
            session.executeCommandSeq(<server.protocol.GeterrRequest>{
                command: "geterr",
                arguments: { files: [f1.path] }
            });

            expectedRequestId = session.getNextSeq();
            session.executeCommandSeq(<server.protocol.OccurrencesRequest>{
                command: "occurrences",
                arguments: { file: f1.path, line: 1, offset: 6 }
            });

            expectedRequestId = 2;
            host.runQueuedImmediateCallbacks();
            expectedRequestId = 2;
            host.runQueuedImmediateCallbacks();
        });

        it("Geterr is cancellable", () => {
            const f1 = {
                path: "/a/app.ts",
                content: "let x = 1"
            };
            const config = {
                path: "/a/tsconfig.json",
                content: JSON.stringify({
                    compilerOptions: {}
                })
            };

            const cancellationToken = new TestServerCancellationToken();
            const host = createServerHost([f1, config]);
            const session = createSession(host, {
                canUseEvents: true,
                eventHandler: noop,
                cancellationToken
            });
            {
                session.executeCommandSeq(<protocol.OpenRequest>{
                    command: "open",
                    arguments: { file: f1.path }
                });
                // send geterr for missing file
                session.executeCommandSeq(<protocol.GeterrRequest>{
                    command: "geterr",
                    arguments: { files: ["/a/missing"] }
                });
                // no files - expect 'completed' event
                assert.equal(host.getOutput().length, 1, "expect 1 message");
                verifyRequestCompleted(session.getSeq(), 0);
            }
            {
                const getErrId = session.getNextSeq();
                // send geterr for a valid file
                session.executeCommandSeq(<protocol.GeterrRequest>{
                    command: "geterr",
                    arguments: { files: [f1.path] }
                });

                assert.equal(host.getOutput().length, 0, "expect 0 messages");

                // run new request
                session.executeCommandSeq(<protocol.ProjectInfoRequest>{
                    command: "projectInfo",
                    arguments: { file: f1.path }
                });
                session.clearMessages();

                // cancel previously issued Geterr
                cancellationToken.setRequestToCancel(getErrId);
                host.runQueuedTimeoutCallbacks();

                assert.equal(host.getOutput().length, 1, "expect 1 message");
                verifyRequestCompleted(getErrId, 0);

                cancellationToken.resetToken();
            }
            {
                const getErrId = session.getNextSeq();
                session.executeCommandSeq(<protocol.GeterrRequest>{
                    command: "geterr",
                    arguments: { files: [f1.path] }
                });
                assert.equal(host.getOutput().length, 0, "expect 0 messages");

                // run first step
                host.runQueuedTimeoutCallbacks();
                assert.equal(host.getOutput().length, 1, "expect 1 message");
                const e1 = <protocol.Event>getMessage(0);
                assert.equal(e1.event, "syntaxDiag");
                session.clearMessages();

                cancellationToken.setRequestToCancel(getErrId);
                host.runQueuedImmediateCallbacks();
                assert.equal(host.getOutput().length, 1, "expect 1 message");
                verifyRequestCompleted(getErrId, 0);

                cancellationToken.resetToken();
            }
            {
                const getErrId = session.getNextSeq();
                session.executeCommandSeq(<protocol.GeterrRequest>{
                    command: "geterr",
                    arguments: { files: [f1.path] }
                });
                assert.equal(host.getOutput().length, 0, "expect 0 messages");

                // run first step
                host.runQueuedTimeoutCallbacks();
                assert.equal(host.getOutput().length, 1, "expect 1 message");
                const e1 = <protocol.Event>getMessage(0);
                assert.equal(e1.event, "syntaxDiag");
                session.clearMessages();

                // the semanticDiag message
                host.runQueuedImmediateCallbacks();
                assert.equal(host.getOutput().length, 1);
                const e2 = <protocol.Event>getMessage(0);
                assert.equal(e2.event, "semanticDiag");
                session.clearMessages();

                host.runQueuedImmediateCallbacks(1);
                assert.equal(host.getOutput().length, 2);
                const e3 = <protocol.Event>getMessage(0);
                assert.equal(e3.event, "suggestionDiag");
                verifyRequestCompleted(getErrId, 1);

                cancellationToken.resetToken();
            }
            {
                const getErr1 = session.getNextSeq();
                session.executeCommandSeq(<protocol.GeterrRequest>{
                    command: "geterr",
                    arguments: { files: [f1.path] }
                });
                assert.equal(host.getOutput().length, 0, "expect 0 messages");
                // run first step
                host.runQueuedTimeoutCallbacks();
                assert.equal(host.getOutput().length, 1, "expect 1 message");
                const e1 = <protocol.Event>getMessage(0);
                assert.equal(e1.event, "syntaxDiag");
                session.clearMessages();

                session.executeCommandSeq(<protocol.GeterrRequest>{
                    command: "geterr",
                    arguments: { files: [f1.path] }
                });
                // make sure that getErr1 is completed
                verifyRequestCompleted(getErr1, 0);
            }

            function verifyRequestCompleted(expectedSeq: number, n: number) {
                const event = <protocol.RequestCompletedEvent>getMessage(n);
                assert.equal(event.event, "requestCompleted");
                assert.equal(event.body.request_seq, expectedSeq, "expectedSeq");
                session.clearMessages();
            }

            function getMessage(n: number) {
                return JSON.parse(server.extractMessage(host.getOutput()[n]));
            }
        });

        it("Lower priority tasks are cancellable", () => {
            const f1 = {
                path: "/a/app.ts",
                content: `{ let x = 1; } var foo = "foo"; var bar = "bar"; var fooBar = "fooBar";`
            };
            const config = {
                path: "/a/tsconfig.json",
                content: JSON.stringify({
                    compilerOptions: {}
                })
            };
            const cancellationToken = new TestServerCancellationToken(/*cancelAfterRequest*/ 3);
            const host = createServerHost([f1, config]);
            const session = createSession(host, {
                canUseEvents: true,
                eventHandler: noop,
                cancellationToken,
                throttleWaitMilliseconds: 0
            });
            {
                session.executeCommandSeq(<protocol.OpenRequest>{
                    command: "open",
                    arguments: { file: f1.path }
                });

                // send navbar request (normal priority)
                session.executeCommandSeq(<protocol.NavBarRequest>{
                    command: "navbar",
                    arguments: { file: f1.path }
                });

                // ensure the nav bar request can be canceled
                verifyExecuteCommandSeqIsCancellable(<protocol.NavBarRequest>{
                    command: "navbar",
                    arguments: { file: f1.path }
                });

                // send outlining spans request (normal priority)
                session.executeCommandSeq(<protocol.OutliningSpansRequestFull>{
                    command: "outliningSpans",
                    arguments: { file: f1.path }
                });

                // ensure the outlining spans request can be canceled
                verifyExecuteCommandSeqIsCancellable(<protocol.OutliningSpansRequestFull>{
                    command: "outliningSpans",
                    arguments: { file: f1.path }
                });
            }

            function verifyExecuteCommandSeqIsCancellable<T extends server.protocol.Request>(request: Partial<T>) {
                // Set the next request to be cancellable
                // The cancellation token will cancel the request the third time
                // isCancellationRequested() is called.
                cancellationToken.setRequestToCancel(session.getNextSeq());
                let operationCanceledExceptionThrown = false;

                try {
                    session.executeCommandSeq(request);
                }
                catch (e) {
                    assert(e instanceof OperationCanceledException);
                    operationCanceledExceptionThrown = true;
                }
                assert(operationCanceledExceptionThrown, "Operation Canceled Exception not thrown for request: " + JSON.stringify(request));
            }
        });
    });

    describe("tsserverProjectSystem occurence highlight on string", () => {
        it("should be marked if only on string values", () => {
            const file1: File = {
                path: "/a/b/file1.ts",
                content: `let t1 = "div";\nlet t2 = "div";\nlet t3 = { "div": 123 };\nlet t4 = t3["div"];`
            };

            const host = createServerHost([file1]);
            const session = createSession(host);
            const projectService = session.getProjectService();

            projectService.openClientFile(file1.path);
            {
                const highlightRequest = makeSessionRequest<protocol.FileLocationRequestArgs>(
                    CommandNames.Occurrences,
                    { file: file1.path, line: 1, offset: 11 }
                );
                const highlightResponse = session.executeCommand(highlightRequest).response as protocol.OccurrencesResponseItem[];
                const firstOccurence = highlightResponse[0];
                assert.isTrue(firstOccurence.isInString, "Highlights should be marked with isInString");
            }

            {
                const highlightRequest = makeSessionRequest<protocol.FileLocationRequestArgs>(
                    CommandNames.Occurrences,
                    { file: file1.path, line: 3, offset: 13 }
                );
                const highlightResponse = session.executeCommand(highlightRequest).response as protocol.OccurrencesResponseItem[];
                assert.isTrue(highlightResponse.length === 2);
                const firstOccurence = highlightResponse[0];
                assert.isUndefined(firstOccurence.isInString, "Highlights should not be marked with isInString if on property name");
            }

            {
                const highlightRequest = makeSessionRequest<protocol.FileLocationRequestArgs>(
                    CommandNames.Occurrences,
                    { file: file1.path, line: 4, offset: 14 }
                );
                const highlightResponse = session.executeCommand(highlightRequest).response as protocol.OccurrencesResponseItem[];
                assert.isTrue(highlightResponse.length === 2);
                const firstOccurence = highlightResponse[0];
                assert.isUndefined(firstOccurence.isInString, "Highlights should not be marked with isInString if on indexer");
            }
        });
    });

    describe("tsserverProjectSystem maxNodeModuleJsDepth for inferred projects", () => {
        it("should be set to 2 if the project has js root files", () => {
            const file1: File = {
                path: "/a/b/file1.js",
                content: `var t = require("test"); t.`
            };
            const moduleFile: File = {
                path: "/a/b/node_modules/test/index.js",
                content: `var v = 10; module.exports = v;`
            };

            const host = createServerHost([file1, moduleFile]);
            const projectService = createProjectService(host);
            projectService.openClientFile(file1.path);

            let project = projectService.inferredProjects[0];
            let options = project.getCompilationSettings();
            assert.isTrue(options.maxNodeModuleJsDepth === 2);

            // Assert the option sticks
            projectService.setCompilerOptionsForInferredProjects({ target: ScriptTarget.ES2016 });
            project = projectService.inferredProjects[0];
            options = project.getCompilationSettings();
            assert.isTrue(options.maxNodeModuleJsDepth === 2);
        });

        it("should return to normal state when all js root files are removed from project", () => {
            const file1 = {
                path: "/a/file1.ts",
                content: "let x =1;"
            };
            const file2 = {
                path: "/a/file2.js",
                content: "let x =1;"
            };

            const host = createServerHost([file1, file2, libFile]);
            const projectService = createProjectService(host, { useSingleInferredProject: true });

            projectService.openClientFile(file1.path);
            checkNumberOfInferredProjects(projectService, 1);
            let project = projectService.inferredProjects[0];
            assert.isUndefined(project.getCompilationSettings().maxNodeModuleJsDepth);

            projectService.openClientFile(file2.path);
            project = projectService.inferredProjects[0];
            assert.isTrue(project.getCompilationSettings().maxNodeModuleJsDepth === 2);

            projectService.closeClientFile(file2.path);
            project = projectService.inferredProjects[0];
            assert.isUndefined(project.getCompilationSettings().maxNodeModuleJsDepth);
        });
    });

    describe("tsserverProjectSystem Options Diagnostic locations reported correctly with changes in configFile contents", () => {
        it("when options change", () => {
            const file = {
                path: "/a/b/app.ts",
                content: "let x = 10"
            };
            const configFileContentBeforeComment = `{`;
            const configFileContentComment = `
                // comment`;
            const configFileContentAfterComment = `
                "compilerOptions": {
                    "allowJs": true,
                    "declaration": true
                }
            }`;
            const configFileContentWithComment = configFileContentBeforeComment + configFileContentComment + configFileContentAfterComment;
            const configFileContentWithoutCommentLine = configFileContentBeforeComment + configFileContentAfterComment;

            const configFile = {
                path: "/a/b/tsconfig.json",
                content: configFileContentWithComment
            };
            const host = createServerHost([file, libFile, configFile]);
            const session = createSession(host);
            openFilesForSession([file], session);

            const projectService = session.getProjectService();
            checkNumberOfProjects(projectService, { configuredProjects: 1 });
            const projectName = configuredProjectAt(projectService, 0).getProjectName();

            const diags = session.executeCommand(<server.protocol.SemanticDiagnosticsSyncRequest>{
                type: "request",
                command: server.CommandNames.SemanticDiagnosticsSync,
                seq: 2,
                arguments: { file: configFile.path, projectFileName: projectName, includeLinePosition: true }
            }).response as ReadonlyArray<server.protocol.DiagnosticWithLinePosition>;
            assert.isTrue(diags.length === 2);

            configFile.content = configFileContentWithoutCommentLine;
            host.reloadFS([file, configFile]);

            const diagsAfterEdit = session.executeCommand(<server.protocol.SemanticDiagnosticsSyncRequest>{
                type: "request",
                command: server.CommandNames.SemanticDiagnosticsSync,
                seq: 2,
                arguments: { file: configFile.path, projectFileName: projectName, includeLinePosition: true }
            }).response as ReadonlyArray<server.protocol.DiagnosticWithLinePosition>;
            assert.isTrue(diagsAfterEdit.length === 2);

            verifyDiagnostic(diags[0], diagsAfterEdit[0]);
            verifyDiagnostic(diags[1], diagsAfterEdit[1]);

            function verifyDiagnostic(beforeEditDiag: server.protocol.DiagnosticWithLinePosition, afterEditDiag: server.protocol.DiagnosticWithLinePosition) {
                assert.equal(beforeEditDiag.message, afterEditDiag.message);
                assert.equal(beforeEditDiag.code, afterEditDiag.code);
                assert.equal(beforeEditDiag.category, afterEditDiag.category);
                assert.equal(beforeEditDiag.startLocation.line, afterEditDiag.startLocation.line + 1);
                assert.equal(beforeEditDiag.startLocation.offset, afterEditDiag.startLocation.offset);
                assert.equal(beforeEditDiag.endLocation.line, afterEditDiag.endLocation.line + 1);
                assert.equal(beforeEditDiag.endLocation.offset, afterEditDiag.endLocation.offset);
            }
        });
    });

    describe("tsserverProjectSystem refactors", () => {
        it("use formatting options", () => {
            const file = {
                path: "/a.ts",
                content: "function f() {\n  1;\n}",
            };
            const host = createServerHost([file]);
            const session = createSession(host);
            openFilesForSession([file], session);

            const response0 = session.executeCommandSeq<server.protocol.ConfigureRequest>({
                command: server.protocol.CommandTypes.Configure,
                arguments: {
                    formatOptions: {
                        indentSize: 2,
                    },
                },
            }).response;
            assert.deepEqual(response0, /*expected*/ undefined);

            const response1 = session.executeCommandSeq<server.protocol.GetEditsForRefactorRequest>({
                command: server.protocol.CommandTypes.GetEditsForRefactor,
                arguments: {
                    refactor: "Extract Symbol",
                    action: "function_scope_1",
                    file: "/a.ts",
                    startLine: 2,
                    startOffset: 3,
                    endLine: 2,
                    endOffset: 4,
                },
            }).response;
            assert.deepEqual(response1, {
                edits: [
                    {
                        fileName: "/a.ts",
                        textChanges: [
                            {
                                start: { line: 2, offset: 3 },
                                end: { line: 2, offset: 5 },
                                newText: "newFunction();",
                            },
                            {
                                start: { line: 3, offset: 2 },
                                end: { line: 3, offset: 2 },
                                newText: "\n\nfunction newFunction() {\n  1;\n}\n",
                            },
                        ]
                    }
                ],
                renameFilename: "/a.ts",
                renameLocation: { line: 2, offset: 3 },
            });
        });

        it("handles text changes in tsconfig.json", () => {
            const aTs = {
                path: "/a.ts",
                content: "export const a = 0;",
            };
            const tsconfig = {
                path: "/tsconfig.json",
                content: '{ "files": ["./a.ts"] }',
            };

            const session = createSession(createServerHost([aTs, tsconfig]));
            openFilesForSession([aTs], session);

            const response1 = session.executeCommandSeq<server.protocol.GetEditsForRefactorRequest>({
                command: server.protocol.CommandTypes.GetEditsForRefactor,
                arguments: {
                    refactor: "Move to a new file",
                    action: "Move to a new file",
                    file: "/a.ts",
                    startLine: 1,
                    startOffset: 1,
                    endLine: 1,
                    endOffset: 20,
                },
            }).response;
            assert.deepEqual(response1, {
                edits: [
                    {
                        fileName: "/a.ts",
                        textChanges: [
                            {
                                start: { line: 1, offset: 1 },
                                end: { line: 1, offset: 20 },
                                newText: "",
                            },
                        ],
                    },
                    {
                        fileName: "/tsconfig.json",
                        textChanges: [
                            {
                                start: { line: 1, offset: 21 },
                                end: { line: 1, offset: 21 },
                                newText: ", \"./a.1.ts\"",
                            },
                        ],
                    },
                    {
                        fileName: "/a.1.ts",
                        textChanges: [
                            {
                              start: { line: 0, offset: 0 },
                              end: { line: 0, offset: 0 },
                              newText: "export const a = 0;",
                            },
                        ],
                    }
                ],
                renameFilename: undefined,
                renameLocation: undefined,
            });
        });
    });

    describe("tsserverProjectSystem CachingFileSystemInformation", () => {
        enum CalledMapsWithSingleArg {
            fileExists = "fileExists",
            directoryExists = "directoryExists",
            getDirectories = "getDirectories",
            readFile = "readFile"
        }
        enum CalledMapsWithFiveArgs {
            readDirectory = "readDirectory"
        }
        type CalledMaps = CalledMapsWithSingleArg | CalledMapsWithFiveArgs;
        function createCallsTrackingHost(host: TestServerHost) {
            const calledMaps: Record<CalledMapsWithSingleArg, MultiMap<true>> & Record<CalledMapsWithFiveArgs, MultiMap<[ReadonlyArray<string>, ReadonlyArray<string>, ReadonlyArray<string>, number]>> = {
                fileExists: setCallsTrackingWithSingleArgFn(CalledMapsWithSingleArg.fileExists),
                directoryExists: setCallsTrackingWithSingleArgFn(CalledMapsWithSingleArg.directoryExists),
                getDirectories: setCallsTrackingWithSingleArgFn(CalledMapsWithSingleArg.getDirectories),
                readFile: setCallsTrackingWithSingleArgFn(CalledMapsWithSingleArg.readFile),
                readDirectory: setCallsTrackingWithFiveArgFn(CalledMapsWithFiveArgs.readDirectory)
            };

            return {
                verifyNoCall,
                verifyCalledOnEachEntryNTimes,
                verifyCalledOnEachEntry,
                verifyNoHostCalls,
                verifyNoHostCallsExceptFileExistsOnce,
                verifyCalledOn,
                clear
            };

            function setCallsTrackingWithSingleArgFn(prop: CalledMapsWithSingleArg) {
                const calledMap = createMultiMap<true>();
                const cb = (<any>host)[prop].bind(host);
                (<any>host)[prop] = (f: string) => {
                    calledMap.add(f, /*value*/ true);
                    return cb(f);
                };
                return calledMap;
            }

            function setCallsTrackingWithFiveArgFn<U, V, W, X>(prop: CalledMapsWithFiveArgs) {
                const calledMap = createMultiMap<[U, V, W, X]>();
                const cb = (<any>host)[prop].bind(host);
                (<any>host)[prop] = (f: string, arg1?: U, arg2?: V, arg3?: W, arg4?: X) => {
                    calledMap.add(f, [arg1!, arg2!, arg3!, arg4!]); // TODO: GH#18217
                    return cb(f, arg1, arg2, arg3, arg4);
                };
                return calledMap;
            }

            function verifyCalledOn(callback: CalledMaps, name: string) {
                const calledMap = calledMaps[callback];
                const result = calledMap.get(name);
                assert.isTrue(result && !!result.length, `${callback} should be called with name: ${name}: ${arrayFrom(calledMap.keys())}`);
            }

            function verifyNoCall(callback: CalledMaps) {
                const calledMap = calledMaps[callback];
                assert.equal(calledMap.size, 0, `${callback} shouldn't be called: ${arrayFrom(calledMap.keys())}`);
            }

            function verifyCalledOnEachEntry(callback: CalledMaps, expectedKeys: Map<number>) {
                TestFSWithWatch.checkMultiMapKeyCount(callback, calledMaps[callback], expectedKeys);
            }

            function verifyCalledOnEachEntryNTimes(callback: CalledMaps, expectedKeys: ReadonlyArray<string>, nTimes: number) {
                TestFSWithWatch.checkMultiMapKeyCount(callback, calledMaps[callback], expectedKeys, nTimes);
            }

            function verifyNoHostCalls() {
                iterateOnCalledMaps(key => verifyNoCall(key));
            }

            function verifyNoHostCallsExceptFileExistsOnce(expectedKeys: ReadonlyArray<string>) {
                verifyCalledOnEachEntryNTimes(CalledMapsWithSingleArg.fileExists, expectedKeys, 1);
                verifyNoCall(CalledMapsWithSingleArg.directoryExists);
                verifyNoCall(CalledMapsWithSingleArg.getDirectories);
                verifyNoCall(CalledMapsWithSingleArg.readFile);
                verifyNoCall(CalledMapsWithFiveArgs.readDirectory);
            }

            function clear() {
                iterateOnCalledMaps(key => calledMaps[key].clear());
            }

            function iterateOnCalledMaps(cb: (key: CalledMaps) => void) {
                for (const key in CalledMapsWithSingleArg) {
                    cb(key as CalledMapsWithSingleArg);
                }
                for (const key in CalledMapsWithFiveArgs) {
                    cb(key as CalledMapsWithFiveArgs);
                }
            }
        }

        it("works using legacy resolution logic", () => {
            let rootContent = `import {x} from "f1"`;
            const root: File = {
                path: "/c/d/f0.ts",
                content: rootContent
            };

            const imported: File = {
                path: "/c/f1.ts",
                content: `foo()`
            };

            const host = createServerHost([root, imported]);
            const projectService = createProjectService(host);
            projectService.setCompilerOptionsForInferredProjects({ module: ModuleKind.AMD, noLib: true });
            projectService.openClientFile(root.path);
            checkNumberOfProjects(projectService, { inferredProjects: 1 });
            const project = projectService.inferredProjects[0];
            const rootScriptInfo = project.getRootScriptInfos()[0];
            assert.equal(rootScriptInfo.fileName, root.path);

            // ensure that imported file was found
            verifyImportedDiagnostics();

            const callsTrackingHost = createCallsTrackingHost(host);

            // trigger synchronization to make sure that import will be fetched from the cache
            // ensure file has correct number of errors after edit
            editContent(`import {x} from "f1";
                 var x: string = 1;`);
            verifyImportedDiagnostics();
            callsTrackingHost.verifyNoHostCalls();

            // trigger synchronization to make sure that LSHost will try to find 'f2' module on disk
            editContent(`import {x} from "f2"`);
            try {
                // trigger synchronization to make sure that LSHost will try to find 'f2' module on disk
                verifyImportedDiagnostics();
                assert.isTrue(false, `should not find file '${imported.path}'`);
            }
            catch (e) {
                assert.isTrue(e.message.indexOf(`Could not find file: '${imported.path}'.`) === 0);
            }
            const f2Lookups = getLocationsForModuleLookup("f2");
            callsTrackingHost.verifyCalledOnEachEntryNTimes(CalledMapsWithSingleArg.fileExists, f2Lookups, 1);
            const f2DirLookups = getLocationsForDirectoryLookup();
            callsTrackingHost.verifyCalledOnEachEntry(CalledMapsWithSingleArg.directoryExists, f2DirLookups);
            callsTrackingHost.verifyNoCall(CalledMapsWithSingleArg.getDirectories);
            callsTrackingHost.verifyNoCall(CalledMapsWithSingleArg.readFile);
            callsTrackingHost.verifyNoCall(CalledMapsWithFiveArgs.readDirectory);

            editContent(`import {x} from "f1"`);
            verifyImportedDiagnostics();
            const f1Lookups = f2Lookups.map(s => s.replace("f2", "f1"));
            f1Lookups.length = f1Lookups.indexOf(imported.path) + 1;
            const f1DirLookups = ["/c/d", "/c", ...mapCombinedPathsInAncestor(getDirectoryPath(root.path), nodeModulesAtTypes, returnTrue)];
            vertifyF1Lookups();

            // setting compiler options discards module resolution cache
            callsTrackingHost.clear();
            projectService.setCompilerOptionsForInferredProjects({ module: ModuleKind.AMD, noLib: true, target: ScriptTarget.ES5 });
            verifyImportedDiagnostics();
            vertifyF1Lookups();

            function vertifyF1Lookups() {
                callsTrackingHost.verifyCalledOnEachEntryNTimes(CalledMapsWithSingleArg.fileExists, f1Lookups, 1);
                callsTrackingHost.verifyCalledOnEachEntryNTimes(CalledMapsWithSingleArg.directoryExists, f1DirLookups, 1);
                callsTrackingHost.verifyNoCall(CalledMapsWithSingleArg.getDirectories);
                callsTrackingHost.verifyNoCall(CalledMapsWithSingleArg.readFile);
                callsTrackingHost.verifyNoCall(CalledMapsWithFiveArgs.readDirectory);
            }

            function editContent(newContent: string) {
                callsTrackingHost.clear();
                rootScriptInfo.editContent(0, rootContent.length, newContent);
                rootContent = newContent;
            }

            function verifyImportedDiagnostics() {
                const diags = project.getLanguageService().getSemanticDiagnostics(imported.path);
                assert.equal(diags.length, 1);
                const diag = diags[0];
                assert.equal(diag.code, Diagnostics.Cannot_find_name_0.code);
                assert.equal(flattenDiagnosticMessageText(diag.messageText, "\n"), "Cannot find name 'foo'.");
            }

            function getLocationsForModuleLookup(module: string) {
                const locations: string[] = [];
                forEachAncestorDirectory(getDirectoryPath(root.path), ancestor => {
                    locations.push(
                        combinePaths(ancestor, `${module}.ts`),
                        combinePaths(ancestor, `${module}.tsx`),
                        combinePaths(ancestor, `${module}.d.ts`)
                    );
                });
                forEachAncestorDirectory(getDirectoryPath(root.path), ancestor => {
                    locations.push(
                        combinePaths(ancestor, `${module}.js`),
                        combinePaths(ancestor, `${module}.jsx`)
                    );
                });
                return locations;
            }

            function getLocationsForDirectoryLookup() {
                const result = createMap<number>();
                forEachAncestorDirectory(getDirectoryPath(root.path), ancestor => {
                    // To resolve modules
                    result.set(ancestor, 2);
                    // for type roots
                    result.set(combinePaths(ancestor, nodeModules), 1);
                    result.set(combinePaths(ancestor, nodeModulesAtTypes), 1);
                });
                return result;
            }
        });

        it("loads missing files from disk", () => {
            const root: File = {
                path: "/c/foo.ts",
                content: `import {y} from "bar"`
            };

            const imported: File = {
                path: "/c/bar.d.ts",
                content: `export var y = 1`
            };

            const host = createServerHost([root]);
            const projectService = createProjectService(host);
            projectService.setCompilerOptionsForInferredProjects({ module: ModuleKind.AMD, noLib: true });
            const callsTrackingHost = createCallsTrackingHost(host);
            projectService.openClientFile(root.path);
            checkNumberOfProjects(projectService, { inferredProjects: 1 });
            const project = projectService.inferredProjects[0];
            const rootScriptInfo = project.getRootScriptInfos()[0];
            assert.equal(rootScriptInfo.fileName, root.path);

            let diags = project.getLanguageService().getSemanticDiagnostics(root.path);
            assert.equal(diags.length, 1);
            const diag = diags[0];
            assert.equal(diag.code, Diagnostics.Cannot_find_module_0.code);
            assert.equal(flattenDiagnosticMessageText(diag.messageText, "\n"), "Cannot find module 'bar'.");
            callsTrackingHost.verifyCalledOn(CalledMapsWithSingleArg.fileExists, imported.path);


            callsTrackingHost.clear();
            host.reloadFS([root, imported]);
            host.runQueuedTimeoutCallbacks();
            diags = project.getLanguageService().getSemanticDiagnostics(root.path);
            assert.equal(diags.length, 0);
            callsTrackingHost.verifyCalledOn(CalledMapsWithSingleArg.fileExists, imported.path);
        });

        it("when calling goto definition of module", () => {
            const clientFile: File = {
                path: "/a/b/controllers/vessels/client.ts",
                content: `
                    import { Vessel } from '~/models/vessel';
                    const v = new Vessel();
                `
            };
            const anotherModuleFile: File = {
                path: "/a/b/utils/db.ts",
                content: "export class Bookshelf { }"
            };
            const moduleFile: File = {
                path: "/a/b/models/vessel.ts",
                content: `
                    import { Bookshelf } from '~/utils/db';
                    export class Vessel extends Bookshelf {}
                `
            };
            const tsconfigFile: File = {
                path: "/a/b/tsconfig.json",
                content: JSON.stringify({
                    compilerOptions: {
                        target: "es6",
                        module: "es6",
                        baseUrl: "./",  // all paths are relative to the baseUrl
                        paths: {
                            "~/*": ["*"]   // resolve any `~/foo/bar` to `<baseUrl>/foo/bar`
                        }
                    },
                    exclude: [
                        "api",
                        "build",
                        "node_modules",
                        "public",
                        "seeds",
                        "sql_updates",
                        "tests.build"
                    ]
                })
            };
            const projectFiles = [clientFile, anotherModuleFile, moduleFile, tsconfigFile];
            const host = createServerHost(projectFiles);
            const session = createSession(host);
            const projectService = session.getProjectService();
            const { configFileName } = projectService.openClientFile(clientFile.path);

            assert.isDefined(configFileName, `should find config`);
            checkNumberOfConfiguredProjects(projectService, 1);

            const project = projectService.configuredProjects.get(tsconfigFile.path)!;
            checkProjectActualFiles(project, map(projectFiles, f => f.path));

            const callsTrackingHost = createCallsTrackingHost(host);

            // Get definitions shouldnt make host requests
            const getDefinitionRequest = makeSessionRequest<protocol.FileLocationRequestArgs>(protocol.CommandTypes.Definition, {
                file: clientFile.path,
                position: clientFile.content.indexOf("/vessel") + 1,
                line: undefined!, // TODO: GH#18217
                offset: undefined! // TODO: GH#18217
            });
            const response = session.executeCommand(getDefinitionRequest).response as server.protocol.FileSpan[];
            assert.equal(response[0].file, moduleFile.path, "Should go to definition of vessel: response: " + JSON.stringify(response));
            callsTrackingHost.verifyNoHostCalls();

            // Open the file should call only file exists on module directory and use cached value for parental directory
            const { configFileName: config2 } = projectService.openClientFile(moduleFile.path);
            assert.equal(config2, configFileName);
            callsTrackingHost.verifyNoHostCallsExceptFileExistsOnce(["/a/b/models/tsconfig.json", "/a/b/models/jsconfig.json"]);

            checkNumberOfConfiguredProjects(projectService, 1);
            assert.strictEqual(projectService.configuredProjects.get(tsconfigFile.path), project);
        });

        describe("WatchDirectories for config file with", () => {
            function verifyWatchDirectoriesCaseSensitivity(useCaseSensitiveFileNames: boolean) {
                const frontendDir = "/Users/someuser/work/applications/frontend";
                const toCanonical: (s: string) => Path = useCaseSensitiveFileNames ? s => s as Path : s => s.toLowerCase() as Path;
                const canonicalFrontendDir = toCanonical(frontendDir);
                const file1: File = {
                    path: `${frontendDir}/src/app/utils/Analytic.ts`,
                    content: "export class SomeClass { };"
                };
                const file2: File = {
                    path: `${frontendDir}/src/app/redux/configureStore.ts`,
                    content: "export class configureStore { }"
                };
                const file3: File = {
                    path: `${frontendDir}/src/app/utils/Cookie.ts`,
                    content: "export class Cookie { }"
                };
                const es2016LibFile: File = {
                    path: "/a/lib/lib.es2016.full.d.ts",
                    content: libFile.content
                };
                const typeRoots = ["types", "node_modules/@types"];
                const types = ["node", "jest"];
                const tsconfigFile: File = {
                    path: `${frontendDir}/tsconfig.json`,
                    content: JSON.stringify({
                        compilerOptions: {
                            strict: true,
                            strictNullChecks: true,
                            target: "es2016",
                            module: "commonjs",
                            moduleResolution: "node",
                            sourceMap: true,
                            noEmitOnError: true,
                            experimentalDecorators: true,
                            emitDecoratorMetadata: true,
                            types,
                            noUnusedLocals: true,
                            outDir: "./compiled",
                            typeRoots,
                            baseUrl: ".",
                            paths: {
                                "*": [
                                    "types/*"
                                ]
                            }
                        },
                        include: [
                            "src/**/*"
                        ],
                        exclude: [
                            "node_modules",
                            "compiled"
                        ]
                    })
                };
                const projectFiles = [file1, file2, es2016LibFile, tsconfigFile];
                const host = createServerHost(projectFiles, { useCaseSensitiveFileNames });
                const projectService = createProjectService(host);
                const canonicalConfigPath = toCanonical(tsconfigFile.path);
                const { configFileName } = projectService.openClientFile(file1.path);
                assert.equal(configFileName, tsconfigFile.path as server.NormalizedPath, `should find config`); // tslint:disable-line no-unnecessary-type-assertion (TODO: GH#18217)
                checkNumberOfConfiguredProjects(projectService, 1);
                const watchingRecursiveDirectories = [`${canonicalFrontendDir}/src`, canonicalFrontendDir].concat(getNodeModuleDirectories(getDirectoryPath(canonicalFrontendDir)));

                const project = projectService.configuredProjects.get(canonicalConfigPath)!;
                verifyProjectAndWatchedDirectories();

                const callsTrackingHost = createCallsTrackingHost(host);

                // Create file cookie.ts
                projectFiles.push(file3);
                host.reloadFS(projectFiles);
                host.runQueuedTimeoutCallbacks();

                const canonicalFile3Path = useCaseSensitiveFileNames ? file3.path : file3.path.toLocaleLowerCase();
                const numberOfTimesWatchInvoked = getNumberOfWatchesInvokedForRecursiveWatches(watchingRecursiveDirectories, canonicalFile3Path);
                callsTrackingHost.verifyCalledOnEachEntryNTimes(CalledMapsWithSingleArg.fileExists, [canonicalFile3Path], numberOfTimesWatchInvoked);
                callsTrackingHost.verifyCalledOnEachEntryNTimes(CalledMapsWithSingleArg.directoryExists, [canonicalFile3Path], numberOfTimesWatchInvoked);
                callsTrackingHost.verifyNoCall(CalledMapsWithSingleArg.getDirectories);
                callsTrackingHost.verifyCalledOnEachEntryNTimes(CalledMapsWithSingleArg.readFile, [file3.path], 1);
                callsTrackingHost.verifyNoCall(CalledMapsWithFiveArgs.readDirectory);

                checkNumberOfConfiguredProjects(projectService, 1);
                assert.strictEqual(projectService.configuredProjects.get(canonicalConfigPath), project);
                verifyProjectAndWatchedDirectories();

                callsTrackingHost.clear();

                const { configFileName: configFile2 } = projectService.openClientFile(file3.path);
                assert.equal(configFile2, configFileName);

                checkNumberOfConfiguredProjects(projectService, 1);
                assert.strictEqual(projectService.configuredProjects.get(canonicalConfigPath), project);
                verifyProjectAndWatchedDirectories();
                callsTrackingHost.verifyNoHostCalls();

                function getFilePathIfNotOpen(f: File) {
                    const path = toCanonical(f.path);
                    const info = projectService.getScriptInfoForPath(toCanonical(f.path));
                    return info && info.isScriptOpen() ? undefined : path;
                }

                function verifyProjectAndWatchedDirectories() {
                    checkProjectActualFiles(project, map(projectFiles, f => f.path));
                    checkWatchedFiles(host, mapDefined(projectFiles, getFilePathIfNotOpen));
                    checkWatchedDirectories(host, watchingRecursiveDirectories, /*recursive*/ true);
                    checkWatchedDirectories(host, [], /*recursive*/ false);
                }
            }

            it("case insensitive file system", () => {
                verifyWatchDirectoriesCaseSensitivity(/*useCaseSensitiveFileNames*/ false);
            });

            it("case sensitive file system", () => {
                verifyWatchDirectoriesCaseSensitivity(/*useCaseSensitiveFileNames*/ true);
            });
        });

        describe("Subfolder invalidations correctly include parent folder failed lookup locations", () => {
            function runFailedLookupTest(resolution: "Node" | "Classic") {
                const projectLocation = "/proj";
                const file1: File = {
                    path: `${projectLocation}/foo/boo/app.ts`,
                    content: `import * as debug from "debug"`
                };
                const file2: File = {
                    path: `${projectLocation}/foo/boo/moo/app.ts`,
                    content: `import * as debug from "debug"`
                };
                const tsconfig: File = {
                    path: `${projectLocation}/tsconfig.json`,
                    content: JSON.stringify({
                        files: ["foo/boo/app.ts", "foo/boo/moo/app.ts"],
                        moduleResolution: resolution
                    })
                };

                const files = [file1, file2, tsconfig, libFile];
                const host = createServerHost(files);
                const service = createProjectService(host);
                service.openClientFile(file1.path);

                const project = service.configuredProjects.get(tsconfig.path)!;
                checkProjectActualFiles(project, files.map(f => f.path));
                assert.deepEqual(project.getLanguageService().getSemanticDiagnostics(file1.path).map(diag => diag.messageText), ["Cannot find module 'debug'."]);
                assert.deepEqual(project.getLanguageService().getSemanticDiagnostics(file2.path).map(diag => diag.messageText), ["Cannot find module 'debug'."]);

                const debugTypesFile: File = {
                    path: `${projectLocation}/node_modules/debug/index.d.ts`,
                    content: "export {}"
                };
                files.push(debugTypesFile);
                host.reloadFS(files);
                host.runQueuedTimeoutCallbacks();
                checkProjectActualFiles(project, files.map(f => f.path));
                assert.deepEqual(project.getLanguageService().getSemanticDiagnostics(file1.path).map(diag => diag.messageText), []);
                assert.deepEqual(project.getLanguageService().getSemanticDiagnostics(file2.path).map(diag => diag.messageText), []);
            }

            it("Includes the parent folder FLLs in node module resolution mode", () => {
                runFailedLookupTest("Node");
            });
            it("Includes the parent folder FLLs in classic module resolution mode", () => {
                runFailedLookupTest("Classic");
            });
        });

        describe("Verify npm install in directory with tsconfig file works when", () => {
            function verifyNpmInstall(timeoutDuringPartialInstallation: boolean) {
                const root = "/user/username/rootfolder/otherfolder";
                const getRootedFileOrFolder = (fileOrFolder: File) => {
                    fileOrFolder.path = root + fileOrFolder.path;
                    return fileOrFolder;
                };
                const app: File = getRootedFileOrFolder({
                    path: "/a/b/app.ts",
                    content: "import _ from 'lodash';"
                });
                const tsconfigJson: File = getRootedFileOrFolder({
                    path: "/a/b/tsconfig.json",
                    content: '{ "compilerOptions": { } }'
                });
                const packageJson: File = getRootedFileOrFolder({
                    path: "/a/b/package.json",
                    content: `
{
  "name": "test",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "dependencies": {
    "lodash",
    "rxjs"
  },
  "devDependencies": {
    "@types/lodash",
    "typescript"
  },
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}
`
                });
                const appFolder = getDirectoryPath(app.path);
                const projectFiles = [app, libFile, tsconfigJson];
                const typeRootDirectories = getTypeRootsFromLocation(getDirectoryPath(tsconfigJson.path));
                const otherFiles = [packageJson];
                const host = createServerHost(projectFiles.concat(otherFiles));
                const projectService = createProjectService(host);
                const { configFileName } = projectService.openClientFile(app.path);
                assert.equal(configFileName, tsconfigJson.path as server.NormalizedPath, `should find config`); // TODO: GH#18217
                const recursiveWatchedDirectories: string[] = [appFolder].concat(getNodeModuleDirectories(getDirectoryPath(appFolder)));
                verifyProject();

                let timeoutAfterReloadFs = timeoutDuringPartialInstallation;

                // Simulate npm install
                const filesAndFoldersToAdd: File[] = [
                    { path: "/a/b/node_modules" },
                    { path: "/a/b/node_modules/.staging/@types" },
                    { path: "/a/b/node_modules/.staging/lodash-b0733faa" },
                    { path: "/a/b/node_modules/.staging/@types/lodash-e56c4fe7" },
                    { path: "/a/b/node_modules/.staging/symbol-observable-24bcbbff" },
                    { path: "/a/b/node_modules/.staging/rxjs-22375c61" },
                    { path: "/a/b/node_modules/.staging/typescript-8493ea5d" },
                    { path: "/a/b/node_modules/.staging/symbol-observable-24bcbbff/package.json", content: "{\n  \"name\": \"symbol-observable\",\n  \"version\": \"1.0.4\",\n  \"description\": \"Symbol.observable ponyfill\",\n  \"license\": \"MIT\",\n  \"repository\": \"blesh/symbol-observable\",\n  \"author\": {\n    \"name\": \"Ben Lesh\",\n    \"email\": \"ben@benlesh.com\"\n  },\n  \"engines\": {\n    \"node\": \">=0.10.0\"\n  },\n  \"scripts\": {\n    \"test\": \"npm run build && mocha && tsc ./ts-test/test.ts && node ./ts-test/test.js && check-es3-syntax -p lib/ --kill\",\n    \"build\": \"babel es --out-dir lib\",\n    \"prepublish\": \"npm test\"\n  },\n  \"files\": [\n    \"" },
                    { path: "/a/b/node_modules/.staging/lodash-b0733faa/package.json", content: "{\n  \"name\": \"lodash\",\n  \"version\": \"4.17.4\",\n  \"description\": \"Lodash modular utilities.\",\n  \"keywords\": \"modules, stdlib, util\",\n  \"homepage\": \"https://lodash.com/\",\n  \"repository\": \"lodash/lodash\",\n  \"icon\": \"https://lodash.com/icon.svg\",\n  \"license\": \"MIT\",\n  \"main\": \"lodash.js\",\n  \"author\": \"John-David Dalton <john.david.dalton@gmail.com> (http://allyoucanleet.com/)\",\n  \"contributors\": [\n    \"John-David Dalton <john.david.dalton@gmail.com> (http://allyoucanleet.com/)\",\n    \"Mathias Bynens <mathias@qiwi." },
                    { path: "/a/b/node_modules/.staging/rxjs-22375c61/package.json", content: "{\n  \"name\": \"rxjs\",\n  \"version\": \"5.4.3\",\n  \"description\": \"Reactive Extensions for modern JavaScript\",\n  \"main\": \"Rx.js\",\n  \"config\": {\n    \"commitizen\": {\n      \"path\": \"cz-conventional-changelog\"\n    }\n  },\n  \"lint-staged\": {\n    \"*.@(js)\": [\n      \"eslint --fix\",\n      \"git add\"\n    ],\n    \"*.@(ts)\": [\n      \"tslint --fix\",\n      \"git add\"\n    ]\n  },\n  \"scripts-info\": {\n    \"info\": \"List available script\",\n    \"build_all\": \"Build all packages (ES6, CJS, UMD) and generate packages\",\n    \"build_cjs\": \"Build CJS package with clean up existing build, copy source into dist\",\n    \"build_es6\": \"Build ES6 package with clean up existing build, copy source into dist\",\n    \"build_closure_core\": \"Minify Global core build using closure compiler\",\n    \"build_global\": \"Build Global package, then minify build\",\n    \"build_perf\": \"Build CJS & Global build, run macro performance test\",\n    \"build_test\": \"Build CJS package & test spec, execute mocha test runner\",\n    \"build_cover\": \"Run lint to current code, build CJS & test spec, execute test coverage\",\n    \"build_docs\": \"Build ES6 & global package, create documentation using it\",\n    \"build_spec\": \"Build test specs\",\n    \"check_circular_dependencies\": \"Check codebase has circular dependencies\",\n    \"clean_spec\": \"Clean up existing test spec build output\",\n    \"clean_dist_cjs\": \"Clean up existing CJS package output\",\n    \"clean_dist_es6\": \"Clean up existing ES6 package output\",\n    \"clean_dist_global\": \"Clean up existing Global package output\",\n    \"commit\": \"Run git commit wizard\",\n    \"compile_dist_cjs\": \"Compile codebase into CJS module\",\n    \"compile_module_es6\": \"Compile codebase into ES6\",\n    \"cover\": \"Execute test coverage\",\n    \"lint_perf\": \"Run lint against performance test suite\",\n    \"lint_spec\": \"Run lint against test spec\",\n    \"lint_src\": \"Run lint against source\",\n    \"lint\": \"Run lint against everything\",\n    \"perf\": \"Run macro performance benchmark\",\n    \"perf_micro\": \"Run micro performance benchmark\",\n    \"test_mocha\": \"Execute mocha test runner against existing test spec build\",\n    \"test_browser\": \"Execute mocha test runner on browser against existing test spec build\",\n    \"test\": \"Clean up existing test spec build, build test spec and execute mocha test runner\",\n    \"tests2png\": \"Generate marble diagram image from test spec\",\n    \"watch\": \"Watch codebase, trigger compile when source code changes\"\n  },\n  \"repository\": {\n    \"type\": \"git\",\n    \"url\": \"git@github.com:ReactiveX/RxJS.git\"\n  },\n  \"keywords\": [\n    \"Rx\",\n    \"RxJS\",\n    \"ReactiveX\",\n    \"ReactiveExtensions\",\n    \"Streams\",\n    \"Observables\",\n    \"Observable\",\n    \"Stream\",\n    \"ES6\",\n    \"ES2015\"\n  ],\n  \"author\": \"Ben Lesh <ben@benlesh.com>\",\n  \"contributors\": [\n    {\n      \"name\": \"Ben Lesh\",\n      \"email\": \"ben@benlesh.com\"\n    },\n    {\n      \"name\": \"Paul Taylor\",\n      \"email\": \"paul.e.taylor@me.com\"\n    },\n    {\n      \"name\": \"Jeff Cross\",\n      \"email\": \"crossj@google.com\"\n    },\n    {\n      \"name\": \"Matthew Podwysocki\",\n      \"email\": \"matthewp@microsoft.com\"\n    },\n    {\n      \"name\": \"OJ Kwon\",\n      \"email\": \"kwon.ohjoong@gmail.com\"\n    },\n    {\n      \"name\": \"Andre Staltz\",\n      \"email\": \"andre@staltz.com\"\n    }\n  ],\n  \"license\": \"Apache-2.0\",\n  \"bugs\": {\n    \"url\": \"https://github.com/ReactiveX/RxJS/issues\"\n  },\n  \"homepage\": \"https://github.com/ReactiveX/RxJS\",\n  \"devDependencies\": {\n    \"babel-polyfill\": \"^6.23.0\",\n    \"benchmark\": \"^2.1.0\",\n    \"benchpress\": \"2.0.0-beta.1\",\n    \"chai\": \"^3.5.0\",\n    \"color\": \"^0.11.1\",\n    \"colors\": \"1.1.2\",\n    \"commitizen\": \"^2.8.6\",\n    \"coveralls\": \"^2.11.13\",\n    \"cz-conventional-changelog\": \"^1.2.0\",\n    \"danger\": \"^1.1.0\",\n    \"doctoc\": \"^1.0.0\",\n    \"escape-string-regexp\": \"^1.0.5 \",\n    \"esdoc\": \"^0.4.7\",\n    \"eslint\": \"^3.8.0\",\n    \"fs-extra\": \"^2.1.2\",\n    \"get-folder-size\": \"^1.0.0\",\n    \"glob\": \"^7.0.3\",\n    \"gm\": \"^1.22.0\",\n    \"google-closure-compiler-js\": \"^20170218.0.0\",\n    \"gzip-size\": \"^3.0.0\",\n    \"http-server\": \"^0.9.0\",\n    \"husky\": \"^0.13.3\",\n    \"lint-staged\": \"3.2.5\",\n    \"lodash\": \"^4.15.0\",\n    \"madge\": \"^1.4.3\",\n    \"markdown-doctest\": \"^0.9.1\",\n    \"minimist\": \"^1.2.0\",\n    \"mkdirp\": \"^0.5.1\",\n    \"mocha\": \"^3.0.2\",\n    \"mocha-in-sauce\": \"0.0.1\",\n    \"npm-run-all\": \"^4.0.2\",\n    \"npm-scripts-info\": \"^0.3.4\",\n    \"nyc\": \"^10.2.0\",\n    \"opn-cli\": \"^3.1.0\",\n    \"platform\": \"^1.3.1\",\n    \"promise\": \"^7.1.1\",\n    \"protractor\": \"^3.1.1\",\n    \"rollup\": \"0.36.3\",\n    \"rollup-plugin-inject\": \"^2.0.0\",\n    \"rollup-plugin-node-resolve\": \"^2.0.0\",\n    \"rx\": \"latest\",\n    \"rxjs\": \"latest\",\n    \"shx\": \"^0.2.2\",\n    \"sinon\": \"^2.1.0\",\n    \"sinon-chai\": \"^2.9.0\",\n    \"source-map-support\": \"^0.4.0\",\n    \"tslib\": \"^1.5.0\",\n    \"tslint\": \"^4.4.2\",\n    \"typescript\": \"~2.0.6\",\n    \"typings\": \"^2.0.0\",\n    \"validate-commit-msg\": \"^2.14.0\",\n    \"watch\": \"^1.0.1\",\n    \"webpack\": \"^1.13.1\",\n    \"xmlhttprequest\": \"1.8.0\"\n  },\n  \"engines\": {\n    \"npm\": \">=2.0.0\"\n  },\n  \"typings\": \"Rx.d.ts\",\n  \"dependencies\": {\n    \"symbol-observable\": \"^1.0.1\"\n  }\n}" },
                    { path: "/a/b/node_modules/.staging/typescript-8493ea5d/package.json", content: "{\n    \"name\": \"typescript\",\n    \"author\": \"Microsoft Corp.\",\n    \"homepage\": \"http://typescriptlang.org/\",\n    \"version\": \"2.4.2\",\n    \"license\": \"Apache-2.0\",\n    \"description\": \"TypeScript is a language for application scale JavaScript development\",\n    \"keywords\": [\n        \"TypeScript\",\n        \"Microsoft\",\n        \"compiler\",\n        \"language\",\n        \"javascript\"\n    ],\n    \"bugs\": {\n        \"url\": \"https://github.com/Microsoft/TypeScript/issues\"\n    },\n    \"repository\": {\n        \"type\": \"git\",\n        \"url\": \"https://github.com/Microsoft/TypeScript.git\"\n    },\n    \"main\": \"./lib/typescript.js\",\n    \"typings\": \"./lib/typescript.d.ts\",\n    \"bin\": {\n        \"tsc\": \"./bin/tsc\",\n        \"tsserver\": \"./bin/tsserver\"\n    },\n    \"engines\": {\n        \"node\": \">=4.2.0\"\n    },\n    \"devDependencies\": {\n        \"@types/browserify\": \"latest\",\n        \"@types/chai\": \"latest\",\n        \"@types/convert-source-map\": \"latest\",\n        \"@types/del\": \"latest\",\n        \"@types/glob\": \"latest\",\n        \"@types/gulp\": \"latest\",\n        \"@types/gulp-concat\": \"latest\",\n        \"@types/gulp-help\": \"latest\",\n        \"@types/gulp-newer\": \"latest\",\n        \"@types/gulp-sourcemaps\": \"latest\",\n        \"@types/merge2\": \"latest\",\n        \"@types/minimatch\": \"latest\",\n        \"@types/minimist\": \"latest\",\n        \"@types/mkdirp\": \"latest\",\n        \"@types/mocha\": \"latest\",\n        \"@types/node\": \"latest\",\n        \"@types/q\": \"latest\",\n        \"@types/run-sequence\": \"latest\",\n        \"@types/through2\": \"latest\",\n        \"browserify\": \"latest\",\n        \"chai\": \"latest\",\n        \"convert-source-map\": \"latest\",\n        \"del\": \"latest\",\n        \"gulp\": \"latest\",\n        \"gulp-clone\": \"latest\",\n        \"gulp-concat\": \"latest\",\n        \"gulp-help\": \"latest\",\n        \"gulp-insert\": \"latest\",\n        \"gulp-newer\": \"latest\",\n        \"gulp-sourcemaps\": \"latest\",\n        \"gulp-typescript\": \"latest\",\n        \"into-stream\": \"latest\",\n        \"istanbul\": \"latest\",\n        \"jake\": \"latest\",\n        \"merge2\": \"latest\",\n        \"minimist\": \"latest\",\n        \"mkdirp\": \"latest\",\n        \"mocha\": \"latest\",\n        \"mocha-fivemat-progress-reporter\": \"latest\",\n        \"q\": \"latest\",\n        \"run-sequence\": \"latest\",\n        \"sorcery\": \"latest\",\n        \"through2\": \"latest\",\n        \"travis-fold\": \"latest\",\n        \"ts-node\": \"latest\",\n        \"tslint\": \"latest\",\n        \"typescript\": \"^2.4\"\n    },\n    \"scripts\": {\n        \"pretest\": \"jake tests\",\n        \"test\": \"jake runtests-parallel\",\n        \"build\": \"npm run build:compiler && npm run build:tests\",\n        \"build:compiler\": \"jake local\",\n        \"build:tests\": \"jake tests\",\n        \"start\": \"node lib/tsc\",\n        \"clean\": \"jake clean\",\n        \"gulp\": \"gulp\",\n        \"jake\": \"jake\",\n        \"lint\": \"jake lint\",\n        \"setup-hooks\": \"node scripts/link-hooks.js\"\n    },\n    \"browser\": {\n        \"buffer\": false,\n        \"fs\": false,\n        \"os\": false,\n        \"path\": false\n    }\n}" },
                    { path: "/a/b/node_modules/.staging/symbol-observable-24bcbbff/index.js", content: "module.exports = require('./lib/index');\n" },
                    { path: "/a/b/node_modules/.staging/symbol-observable-24bcbbff/index.d.ts", content: "declare const observableSymbol: symbol;\nexport default observableSymbol;\n" },
                    { path: "/a/b/node_modules/.staging/symbol-observable-24bcbbff/lib" },
                    { path: "/a/b/node_modules/.staging/symbol-observable-24bcbbff/lib/index.js", content: "'use strict';\n\nObject.defineProperty(exports, \"__esModule\", {\n  value: true\n});\n\nvar _ponyfill = require('./ponyfill');\n\nvar _ponyfill2 = _interopRequireDefault(_ponyfill);\n\nfunction _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { 'default': obj }; }\n\nvar root; /* global window */\n\n\nif (typeof self !== 'undefined') {\n  root = self;\n} else if (typeof window !== 'undefined') {\n  root = window;\n} else if (typeof global !== 'undefined') {\n  root = global;\n} else if (typeof module !== 'undefined') {\n  root = module;\n} else {\n  root = Function('return this')();\n}\n\nvar result = (0, _ponyfill2['default'])(root);\nexports['default'] = result;" },
                ].map(getRootedFileOrFolder);
                verifyAfterPartialOrCompleteNpmInstall(2);

                filesAndFoldersToAdd.push(...[
                    { path: "/a/b/node_modules/.staging/typescript-8493ea5d/lib" },
                    { path: "/a/b/node_modules/.staging/rxjs-22375c61/add/operator" },
                    { path: "/a/b/node_modules/.staging/@types/lodash-e56c4fe7/package.json", content: "{\n    \"name\": \"@types/lodash\",\n    \"version\": \"4.14.74\",\n    \"description\": \"TypeScript definitions for Lo-Dash\",\n    \"license\": \"MIT\",\n    \"contributors\": [\n        {\n            \"name\": \"Brian Zengel\",\n            \"url\": \"https://github.com/bczengel\"\n        },\n        {\n            \"name\": \"Ilya Mochalov\",\n            \"url\": \"https://github.com/chrootsu\"\n        },\n        {\n            \"name\": \"Stepan Mikhaylyuk\",\n            \"url\": \"https://github.com/stepancar\"\n        },\n        {\n            \"name\": \"Eric L Anderson\",\n            \"url\": \"https://github.com/ericanderson\"\n        },\n        {\n            \"name\": \"AJ Richardson\",\n            \"url\": \"https://github.com/aj-r\"\n        },\n        {\n            \"name\": \"Junyoung Clare Jang\",\n            \"url\": \"https://github.com/ailrun\"\n        }\n    ],\n    \"main\": \"\",\n    \"repository\": {\n        \"type\": \"git\",\n        \"url\": \"https://www.github.com/DefinitelyTyped/DefinitelyTyped.git\"\n    },\n    \"scripts\": {},\n    \"dependencies\": {},\n    \"typesPublisherContentHash\": \"12af578ffaf8d86d2df37e591857906a86b983fa9258414326544a0fe6af0de8\",\n    \"typeScriptVersion\": \"2.2\"\n}" },
                    { path: "/a/b/node_modules/.staging/lodash-b0733faa/index.js", content: "module.exports = require('./lodash');" },
                    { path: "/a/b/node_modules/.staging/typescript-8493ea5d/package.json.3017591594" }
                ].map(getRootedFileOrFolder));
                // Since we added/removed folder, scheduled project update
                verifyAfterPartialOrCompleteNpmInstall(2);

                // Remove file "/a/b/node_modules/.staging/typescript-8493ea5d/package.json.3017591594"
                filesAndFoldersToAdd.length--;
                verifyAfterPartialOrCompleteNpmInstall(0);

                filesAndFoldersToAdd.push(...[
                    { path: "/a/b/node_modules/.staging/rxjs-22375c61/bundles" },
                    { path: "/a/b/node_modules/.staging/rxjs-22375c61/operator" },
                    { path: "/a/b/node_modules/.staging/rxjs-22375c61/src/add/observable/dom" },
                    { path: "/a/b/node_modules/.staging/@types/lodash-e56c4fe7/index.d.ts", content: "\n// Stub for lodash\nexport = _;\nexport as namespace _;\ndeclare var _: _.LoDashStatic;\ndeclare namespace _ {\n    interface LoDashStatic {\n        someProp: string;\n    }\n    class SomeClass {\n        someMethod(): void;\n    }\n}" }
                ].map(getRootedFileOrFolder));
                verifyAfterPartialOrCompleteNpmInstall(2);

                filesAndFoldersToAdd.push(...[
                    { path: "/a/b/node_modules/.staging/rxjs-22375c61/src/scheduler" },
                    { path: "/a/b/node_modules/.staging/rxjs-22375c61/src/util" },
                    { path: "/a/b/node_modules/.staging/rxjs-22375c61/symbol" },
                    { path: "/a/b/node_modules/.staging/rxjs-22375c61/testing" },
                    { path: "/a/b/node_modules/.staging/rxjs-22375c61/package.json.2252192041", content: "{\n  \"_args\": [\n    [\n      {\n        \"raw\": \"rxjs@^5.4.2\",\n        \"scope\": null,\n        \"escapedName\": \"rxjs\",\n        \"name\": \"rxjs\",\n        \"rawSpec\": \"^5.4.2\",\n        \"spec\": \">=5.4.2 <6.0.0\",\n        \"type\": \"range\"\n      },\n      \"C:\\\\Users\\\\shkamat\\\\Desktop\\\\app\"\n    ]\n  ],\n  \"_from\": \"rxjs@>=5.4.2 <6.0.0\",\n  \"_id\": \"rxjs@5.4.3\",\n  \"_inCache\": true,\n  \"_location\": \"/rxjs\",\n  \"_nodeVersion\": \"7.7.2\",\n  \"_npmOperationalInternal\": {\n    \"host\": \"s3://npm-registry-packages\",\n    \"tmp\": \"tmp/rxjs-5.4.3.tgz_1502407898166_0.6800217325799167\"\n  },\n  \"_npmUser\": {\n    \"name\": \"blesh\",\n    \"email\": \"ben@benlesh.com\"\n  },\n  \"_npmVersion\": \"5.3.0\",\n  \"_phantomChildren\": {},\n  \"_requested\": {\n    \"raw\": \"rxjs@^5.4.2\",\n    \"scope\": null,\n    \"escapedName\": \"rxjs\",\n    \"name\": \"rxjs\",\n    \"rawSpec\": \"^5.4.2\",\n    \"spec\": \">=5.4.2 <6.0.0\",\n    \"type\": \"range\"\n  },\n  \"_requiredBy\": [\n    \"/\"\n  ],\n  \"_resolved\": \"https://registry.npmjs.org/rxjs/-/rxjs-5.4.3.tgz\",\n  \"_shasum\": \"0758cddee6033d68e0fd53676f0f3596ce3d483f\",\n  \"_shrinkwrap\": null,\n  \"_spec\": \"rxjs@^5.4.2\",\n  \"_where\": \"C:\\\\Users\\\\shkamat\\\\Desktop\\\\app\",\n  \"author\": {\n    \"name\": \"Ben Lesh\",\n    \"email\": \"ben@benlesh.com\"\n  },\n  \"bugs\": {\n    \"url\": \"https://github.com/ReactiveX/RxJS/issues\"\n  },\n  \"config\": {\n    \"commitizen\": {\n      \"path\": \"cz-conventional-changelog\"\n    }\n  },\n  \"contributors\": [\n    {\n      \"name\": \"Ben Lesh\",\n      \"email\": \"ben@benlesh.com\"\n    },\n    {\n      \"name\": \"Paul Taylor\",\n      \"email\": \"paul.e.taylor@me.com\"\n    },\n    {\n      \"name\": \"Jeff Cross\",\n      \"email\": \"crossj@google.com\"\n    },\n    {\n      \"name\": \"Matthew Podwysocki\",\n      \"email\": \"matthewp@microsoft.com\"\n    },\n    {\n      \"name\": \"OJ Kwon\",\n      \"email\": \"kwon.ohjoong@gmail.com\"\n    },\n    {\n      \"name\": \"Andre Staltz\",\n      \"email\": \"andre@staltz.com\"\n    }\n  ],\n  \"dependencies\": {\n    \"symbol-observable\": \"^1.0.1\"\n  },\n  \"description\": \"Reactive Extensions for modern JavaScript\",\n  \"devDependencies\": {\n    \"babel-polyfill\": \"^6.23.0\",\n    \"benchmark\": \"^2.1.0\",\n    \"benchpress\": \"2.0.0-beta.1\",\n    \"chai\": \"^3.5.0\",\n    \"color\": \"^0.11.1\",\n    \"colors\": \"1.1.2\",\n    \"commitizen\": \"^2.8.6\",\n    \"coveralls\": \"^2.11.13\",\n    \"cz-conventional-changelog\": \"^1.2.0\",\n    \"danger\": \"^1.1.0\",\n    \"doctoc\": \"^1.0.0\",\n    \"escape-string-regexp\": \"^1.0.5 \",\n    \"esdoc\": \"^0.4.7\",\n    \"eslint\": \"^3.8.0\",\n    \"fs-extra\": \"^2.1.2\",\n    \"get-folder-size\": \"^1.0.0\",\n    \"glob\": \"^7.0.3\",\n    \"gm\": \"^1.22.0\",\n    \"google-closure-compiler-js\": \"^20170218.0.0\",\n    \"gzip-size\": \"^3.0.0\",\n    \"http-server\": \"^0.9.0\",\n    \"husky\": \"^0.13.3\",\n    \"lint-staged\": \"3.2.5\",\n    \"lodash\": \"^4.15.0\",\n    \"madge\": \"^1.4.3\",\n    \"markdown-doctest\": \"^0.9.1\",\n    \"minimist\": \"^1.2.0\",\n    \"mkdirp\": \"^0.5.1\",\n    \"mocha\": \"^3.0.2\",\n    \"mocha-in-sauce\": \"0.0.1\",\n    \"npm-run-all\": \"^4.0.2\",\n    \"npm-scripts-info\": \"^0.3.4\",\n    \"nyc\": \"^10.2.0\",\n    \"opn-cli\": \"^3.1.0\",\n    \"platform\": \"^1.3.1\",\n    \"promise\": \"^7.1.1\",\n    \"protractor\": \"^3.1.1\",\n    \"rollup\": \"0.36.3\",\n    \"rollup-plugin-inject\": \"^2.0.0\",\n    \"rollup-plugin-node-resolve\": \"^2.0.0\",\n    \"rx\": \"latest\",\n    \"rxjs\": \"latest\",\n    \"shx\": \"^0.2.2\",\n    \"sinon\": \"^2.1.0\",\n    \"sinon-chai\": \"^2.9.0\",\n    \"source-map-support\": \"^0.4.0\",\n    \"tslib\": \"^1.5.0\",\n    \"tslint\": \"^4.4.2\",\n    \"typescript\": \"~2.0.6\",\n    \"typings\": \"^2.0.0\",\n    \"validate-commit-msg\": \"^2.14.0\",\n    \"watch\": \"^1.0.1\",\n    \"webpack\": \"^1.13.1\",\n    \"xmlhttprequest\": \"1.8.0\"\n  },\n  \"directories\": {},\n  \"dist\": {\n    \"integrity\": \"sha512-fSNi+y+P9ss+EZuV0GcIIqPUK07DEaMRUtLJvdcvMyFjc9dizuDjere+A4V7JrLGnm9iCc+nagV/4QdMTkqC4A==\",\n    \"shasum\": \"0758cddee6033d68e0fd53676f0f3596ce3d483f\",\n    \"tarball\": \"https://registry.npmjs.org/rxjs/-/rxjs-5.4.3.tgz\"\n  },\n  \"engines\": {\n    \"npm\": \">=2.0.0\"\n  },\n  \"homepage\": \"https://github.com/ReactiveX/RxJS\",\n  \"keywords\": [\n    \"Rx\",\n    \"RxJS\",\n    \"ReactiveX\",\n    \"ReactiveExtensions\",\n    \"Streams\",\n    \"Observables\",\n    \"Observable\",\n    \"Stream\",\n    \"ES6\",\n    \"ES2015\"\n  ],\n  \"license\": \"Apache-2.0\",\n  \"lint-staged\": {\n    \"*.@(js)\": [\n      \"eslint --fix\",\n      \"git add\"\n    ],\n    \"*.@(ts)\": [\n      \"tslint --fix\",\n      \"git add\"\n    ]\n  },\n  \"main\": \"Rx.js\",\n  \"maintainers\": [\n    {\n      \"name\": \"blesh\",\n      \"email\": \"ben@benlesh.com\"\n    }\n  ],\n  \"name\": \"rxjs\",\n  \"optionalDependencies\": {},\n  \"readme\": \"ERROR: No README data found!\",\n  \"repository\": {\n    \"type\": \"git\",\n    \"url\": \"git+ssh://git@github.com/ReactiveX/RxJS.git\"\n  },\n  \"scripts-info\": {\n    \"info\": \"List available script\",\n    \"build_all\": \"Build all packages (ES6, CJS, UMD) and generate packages\",\n    \"build_cjs\": \"Build CJS package with clean up existing build, copy source into dist\",\n    \"build_es6\": \"Build ES6 package with clean up existing build, copy source into dist\",\n    \"build_closure_core\": \"Minify Global core build using closure compiler\",\n    \"build_global\": \"Build Global package, then minify build\",\n    \"build_perf\": \"Build CJS & Global build, run macro performance test\",\n    \"build_test\": \"Build CJS package & test spec, execute mocha test runner\",\n    \"build_cover\": \"Run lint to current code, build CJS & test spec, execute test coverage\",\n    \"build_docs\": \"Build ES6 & global package, create documentation using it\",\n    \"build_spec\": \"Build test specs\",\n    \"check_circular_dependencies\": \"Check codebase has circular dependencies\",\n    \"clean_spec\": \"Clean up existing test spec build output\",\n    \"clean_dist_cjs\": \"Clean up existing CJS package output\",\n    \"clean_dist_es6\": \"Clean up existing ES6 package output\",\n    \"clean_dist_global\": \"Clean up existing Global package output\",\n    \"commit\": \"Run git commit wizard\",\n    \"compile_dist_cjs\": \"Compile codebase into CJS module\",\n    \"compile_module_es6\": \"Compile codebase into ES6\",\n    \"cover\": \"Execute test coverage\",\n    \"lint_perf\": \"Run lint against performance test suite\",\n    \"lint_spec\": \"Run lint against test spec\",\n    \"lint_src\": \"Run lint against source\",\n    \"lint\": \"Run lint against everything\",\n    \"perf\": \"Run macro performance benchmark\",\n    \"perf_micro\": \"Run micro performance benchmark\",\n    \"test_mocha\": \"Execute mocha test runner against existing test spec build\",\n    \"test_browser\": \"Execute mocha test runner on browser against existing test spec build\",\n    \"test\": \"Clean up existing test spec build, build test spec and execute mocha test runner\",\n    \"tests2png\": \"Generate marble diagram image from test spec\",\n    \"watch\": \"Watch codebase, trigger compile when source code changes\"\n  },\n  \"typings\": \"Rx.d.ts\",\n  \"version\": \"5.4.3\"\n}\n" }
                ].map(getRootedFileOrFolder));
                verifyAfterPartialOrCompleteNpmInstall(2);

                // remove /a/b/node_modules/.staging/rxjs-22375c61/package.json.2252192041
                filesAndFoldersToAdd.length--;
                // and add few more folders/files
                filesAndFoldersToAdd.push(...[
                    { path: "/a/b/node_modules/symbol-observable" },
                    { path: "/a/b/node_modules/@types" },
                    { path: "/a/b/node_modules/@types/lodash" },
                    { path: "/a/b/node_modules/lodash" },
                    { path: "/a/b/node_modules/rxjs" },
                    { path: "/a/b/node_modules/typescript" },
                    { path: "/a/b/node_modules/.bin" }
                ].map(getRootedFileOrFolder));
                // From the type root update
                verifyAfterPartialOrCompleteNpmInstall(2);

                forEach(filesAndFoldersToAdd, f => {
                    f.path = f.path
                        .replace("/a/b/node_modules/.staging", "/a/b/node_modules")
                        .replace(/[\-\.][\d\w][\d\w][\d\w][\d\w][\d\w][\d\w][\d\w][\d\w]/g, "");
                });

                const lodashIndexPath = root + "/a/b/node_modules/@types/lodash/index.d.ts";
                projectFiles.push(find(filesAndFoldersToAdd, f => f.path === lodashIndexPath)!);
                // we would now not have failed lookup in the parent of appFolder since lodash is available
                recursiveWatchedDirectories.length = 1;
                // npm installation complete, timeout after reload fs
                timeoutAfterReloadFs = true;
                verifyAfterPartialOrCompleteNpmInstall(2);

                function verifyAfterPartialOrCompleteNpmInstall(timeoutQueueLengthWhenRunningTimeouts: number) {
                    host.reloadFS(projectFiles.concat(otherFiles, filesAndFoldersToAdd));
                    if (timeoutAfterReloadFs) {
                        host.checkTimeoutQueueLengthAndRun(timeoutQueueLengthWhenRunningTimeouts);
                    }
                    else {
                        host.checkTimeoutQueueLength(2);
                    }
                    verifyProject();
                }

                function verifyProject() {
                    checkNumberOfConfiguredProjects(projectService, 1);

                    const project = projectService.configuredProjects.get(tsconfigJson.path)!;
                    const projectFilePaths = map(projectFiles, f => f.path);
                    checkProjectActualFiles(project, projectFilePaths);

                    const filesWatched = filter(projectFilePaths, p => p !== app.path);
                    checkWatchedFiles(host, filesWatched);
                    checkWatchedDirectories(host, typeRootDirectories.concat(recursiveWatchedDirectories), /*recursive*/ true);
                    checkWatchedDirectories(host, [], /*recursive*/ false);
                }
            }

            it("timeouts occur inbetween installation", () => {
                verifyNpmInstall(/*timeoutDuringPartialInstallation*/ true);
            });

            it("timeout occurs after installation", () => {
                verifyNpmInstall(/*timeoutDuringPartialInstallation*/ false);
            });
        });

        it("when node_modules dont receive event for the @types file addition", () => {
            const projectLocation = "/user/username/folder/myproject";
            const app: File = {
                path: `${projectLocation}/app.ts`,
                content: `import * as debug from "debug"`
            };
            const tsconfig: File = {
                path: `${projectLocation}/tsconfig.json`,
                content: ""
            };

            const files = [app, tsconfig, libFile];
            const host = createServerHost(files);
            const service = createProjectService(host);
            service.openClientFile(app.path);

            const project = service.configuredProjects.get(tsconfig.path)!;
            checkProjectActualFiles(project, files.map(f => f.path));
            assert.deepEqual(project.getLanguageService().getSemanticDiagnostics(app.path).map(diag => diag.messageText), ["Cannot find module 'debug'."]);

            const debugTypesFile: File = {
                path: `${projectLocation}/node_modules/@types/debug/index.d.ts`,
                content: "export {}"
            };
            files.push(debugTypesFile);
            // Do not invoke recursive directory watcher for anything other than node_module/@types
            const invoker = host.invokeWatchedDirectoriesRecursiveCallback;
            host.invokeWatchedDirectoriesRecursiveCallback = (fullPath, relativePath) => {
                if (fullPath.endsWith("@types")) {
                    invoker.call(host, fullPath, relativePath);
                }
            };
            host.reloadFS(files);
            host.runQueuedTimeoutCallbacks();
            checkProjectActualFiles(project, files.map(f => f.path));
            assert.deepEqual(project.getLanguageService().getSemanticDiagnostics(app.path).map(diag => diag.messageText), []);
        });
    });

    describe("tsserverProjectSystem ProjectsChangedInBackground", () => {
        function verifyFiles(caption: string, actual: ReadonlyArray<string>, expected: ReadonlyArray<string>) {
            assert.equal(actual.length, expected.length, `Incorrect number of ${caption}. Actual: ${actual} Expected: ${expected}`);
            const seen = createMap<true>();
            forEach(actual, f => {
                assert.isFalse(seen.has(f), `${caption}: Found duplicate ${f}. Actual: ${actual} Expected: ${expected}`);
                seen.set(f, true);
                assert.isTrue(contains(expected, f), `${caption}: Expected not to contain ${f}. Actual: ${actual} Expected: ${expected}`);
            });
        }

        function createVerifyInitialOpen(session: TestSession, verifyProjectsUpdatedInBackgroundEventHandler: (events: server.ProjectsUpdatedInBackgroundEvent[]) => void) {
            return (file: File) => {
                session.executeCommandSeq(<protocol.OpenRequest>{
                    command: server.CommandNames.Open,
                    arguments: {
                        file: file.path
                    }
                });
                verifyProjectsUpdatedInBackgroundEventHandler([]);
            };
        }

        interface ProjectsUpdatedInBackgroundEventVerifier {
            session: TestSession;
            verifyProjectsUpdatedInBackgroundEventHandler(events: server.ProjectsUpdatedInBackgroundEvent[]): void;
            verifyInitialOpen(file: File): void;
        }

        function verifyProjectsUpdatedInBackgroundEvent(createSession: (host: TestServerHost) => ProjectsUpdatedInBackgroundEventVerifier) {
            it("when adding new file", () => {
                const commonFile1: File = {
                    path: "/a/b/file1.ts",
                    content: "export var x = 10;"
                };
                const commonFile2: File = {
                    path: "/a/b/file2.ts",
                    content: "export var y = 10;"
                };
                const commonFile3: File = {
                    path: "/a/b/file3.ts",
                    content: "export var z = 10;"
                };
                const configFile: File = {
                    path: "/a/b/tsconfig.json",
                    content: `{}`
                };
                const openFiles = [commonFile1.path];
                const host = createServerHost([commonFile1, libFile, configFile]);
                const { verifyProjectsUpdatedInBackgroundEventHandler, verifyInitialOpen } = createSession(host);
                verifyInitialOpen(commonFile1);

                host.reloadFS([commonFile1, libFile, configFile, commonFile2]);
                host.runQueuedTimeoutCallbacks();
                verifyProjectsUpdatedInBackgroundEventHandler([{
                    eventName: server.ProjectsUpdatedInBackgroundEvent,
                    data: {
                        openFiles
                    }
                }]);

                host.reloadFS([commonFile1, commonFile2, libFile, configFile, commonFile3]);
                host.runQueuedTimeoutCallbacks();
                verifyProjectsUpdatedInBackgroundEventHandler([{
                    eventName: server.ProjectsUpdatedInBackgroundEvent,
                    data: {
                        openFiles
                    }
                }]);
            });

            describe("with --out or --outFile setting", () => {
                function verifyEventWithOutSettings(compilerOptions: CompilerOptions = {}) {
                    const config: File = {
                        path: "/a/tsconfig.json",
                        content: JSON.stringify({
                            compilerOptions
                        })
                    };

                    const f1: File = {
                        path: "/a/a.ts",
                        content: "export let x = 1"
                    };
                    const f2: File = {
                        path: "/a/b.ts",
                        content: "export let y = 1"
                    };

                    const openFiles = [f1.path];
                    const files = [f1, config, libFile];
                    const host = createServerHost(files);
                    const { verifyInitialOpen, verifyProjectsUpdatedInBackgroundEventHandler } = createSession(host);
                    verifyInitialOpen(f1);

                    files.push(f2);
                    host.reloadFS(files);
                    host.runQueuedTimeoutCallbacks();

                    verifyProjectsUpdatedInBackgroundEventHandler([{
                        eventName: server.ProjectsUpdatedInBackgroundEvent,
                        data: {
                            openFiles
                        }
                    }]);

                    f2.content = "export let x = 11";
                    host.reloadFS(files);
                    host.runQueuedTimeoutCallbacks();
                    verifyProjectsUpdatedInBackgroundEventHandler([{
                        eventName: server.ProjectsUpdatedInBackgroundEvent,
                        data: {
                            openFiles
                        }
                    }]);
                }

                it("when both options are not set", () => {
                    verifyEventWithOutSettings();
                });

                it("when --out is set", () => {
                    const outJs = "/a/out.js";
                    verifyEventWithOutSettings({ out: outJs });
                });

                it("when --outFile is set", () => {
                    const outJs = "/a/out.js";
                    verifyEventWithOutSettings({ outFile: outJs });
                });
            });

            describe("with modules and configured project", () => {
                const file1Consumer1Path = "/a/b/file1Consumer1.ts";
                const moduleFile1Path = "/a/b/moduleFile1.ts";
                const configFilePath = "/a/b/tsconfig.json";
                interface InitialStateParams {
                    /** custom config file options */
                    configObj?: any;
                    /** Additional files and folders to add */
                    getAdditionalFileOrFolder?(): File[];
                    /** initial list of files to reload in fs and first file in this list being the file to open */
                    firstReloadFileList?: string[];
                }
                function getInitialState({ configObj = {}, getAdditionalFileOrFolder, firstReloadFileList }: InitialStateParams = {}) {
                    const moduleFile1: File = {
                        path: moduleFile1Path,
                        content: "export function Foo() { };",
                    };

                    const file1Consumer1: File = {
                        path: file1Consumer1Path,
                        content: `import {Foo} from "./moduleFile1"; export var y = 10;`,
                    };

                    const file1Consumer2: File = {
                        path: "/a/b/file1Consumer2.ts",
                        content: `import {Foo} from "./moduleFile1"; let z = 10;`,
                    };

                    const moduleFile2: File = {
                        path: "/a/b/moduleFile2.ts",
                        content: `export var Foo4 = 10;`,
                    };

                    const globalFile3: File = {
                        path: "/a/b/globalFile3.ts",
                        content: `interface GlobalFoo { age: number }`
                    };

                    const additionalFiles = getAdditionalFileOrFolder ? getAdditionalFileOrFolder() : [];
                    const configFile = {
                        path: configFilePath,
                        content: JSON.stringify(configObj || { compilerOptions: {} })
                    };

                    const files: File[] = [file1Consumer1, moduleFile1, file1Consumer2, moduleFile2, ...additionalFiles, globalFile3, libFile, configFile];

                    const filesToReload = firstReloadFileList && getFiles(firstReloadFileList) || files;
                    const host = createServerHost([filesToReload[0], configFile]);

                    // Initial project creation
                    const { session, verifyProjectsUpdatedInBackgroundEventHandler, verifyInitialOpen } = createSession(host);
                    const openFiles = [filesToReload[0].path];
                    verifyInitialOpen(filesToReload[0]);

                    // Since this is first event, it will have all the files
                    verifyProjectsUpdatedInBackgroundEvent(filesToReload);

                    return {
                        moduleFile1, file1Consumer1, file1Consumer2, moduleFile2, globalFile3, configFile,
                        files,
                        updateContentOfOpenFile,
                        verifyNoProjectsUpdatedInBackgroundEvent,
                        verifyProjectsUpdatedInBackgroundEvent
                    };

                    function getFiles(filelist: string[]) {
                        return map(filelist, getFile);
                    }

                    function getFile(fileName: string) {
                        return find(files, file => file.path === fileName)!;
                    }

                    function verifyNoProjectsUpdatedInBackgroundEvent(filesToReload?: File[]) {
                        host.reloadFS(filesToReload || files);
                        host.runQueuedTimeoutCallbacks();
                        verifyProjectsUpdatedInBackgroundEventHandler([]);
                    }

                    function verifyProjectsUpdatedInBackgroundEvent(filesToReload?: File[]) {
                        host.reloadFS(filesToReload || files);
                        host.runQueuedTimeoutCallbacks();
                        verifyProjectsUpdatedInBackgroundEventHandler([{
                            eventName: server.ProjectsUpdatedInBackgroundEvent,
                            data: {
                                openFiles
                            }
                        }]);
                    }

                    function updateContentOfOpenFile(file: File, newContent: string) {
                        session.executeCommandSeq<protocol.ChangeRequest>({
                            command: server.CommandNames.Change,
                            arguments: {
                                file: file.path,
                                insertString: newContent,
                                endLine: 1,
                                endOffset: file.content.length,
                                line: 1,
                                offset: 1
                            }
                        });
                        file.content = newContent;
                    }
                }

                it("should contains only itself if a module file's shape didn't change, and all files referencing it if its shape changed", () => {
                    const { moduleFile1, verifyProjectsUpdatedInBackgroundEvent } = getInitialState();

                    // Change the content of moduleFile1 to `export var T: number;export function Foo() { };`
                    moduleFile1.content = `export var T: number;export function Foo() { };`;
                    verifyProjectsUpdatedInBackgroundEvent();

                    // Change the content of moduleFile1 to `export var T: number;export function Foo() { console.log('hi'); };`
                    moduleFile1.content = `export var T: number;export function Foo() { console.log('hi'); };`;
                    verifyProjectsUpdatedInBackgroundEvent();
                });

                it("should be up-to-date with the reference map changes", () => {
                    const { moduleFile1, file1Consumer1, updateContentOfOpenFile, verifyProjectsUpdatedInBackgroundEvent, verifyNoProjectsUpdatedInBackgroundEvent } = getInitialState();

                    // Change file1Consumer1 content to `export let y = Foo();`
                    updateContentOfOpenFile(file1Consumer1, "export let y = Foo();");
                    verifyNoProjectsUpdatedInBackgroundEvent();

                    // Change the content of moduleFile1 to `export var T: number;export function Foo() { };`
                    moduleFile1.content = `export var T: number;export function Foo() { };`;
                    verifyProjectsUpdatedInBackgroundEvent();

                    // Add the import statements back to file1Consumer1
                    updateContentOfOpenFile(file1Consumer1, `import {Foo} from "./moduleFile1";let y = Foo();`);
                    verifyNoProjectsUpdatedInBackgroundEvent();

                    // Change the content of moduleFile1 to `export var T: number;export var T2: string;export function Foo() { };`
                    moduleFile1.content = `export var T: number;export var T2: string;export function Foo() { };`;
                    verifyProjectsUpdatedInBackgroundEvent();

                    // Multiple file edits in one go:

                    // Change file1Consumer1 content to `export let y = Foo();`
                    // Change the content of moduleFile1 to `export var T: number;export function Foo() { };`
                    updateContentOfOpenFile(file1Consumer1, `export let y = Foo();`);
                    moduleFile1.content = `export var T: number;export function Foo() { };`;
                    verifyProjectsUpdatedInBackgroundEvent();
                });

                it("should be up-to-date with deleted files", () => {
                    const { moduleFile1, file1Consumer2, files, verifyProjectsUpdatedInBackgroundEvent } = getInitialState();

                    // Change the content of moduleFile1 to `export var T: number;export function Foo() { };`
                    moduleFile1.content = `export var T: number;export function Foo() { };`;

                    // Delete file1Consumer2
                    const filesToLoad = filter(files, file => file !== file1Consumer2);
                    verifyProjectsUpdatedInBackgroundEvent(filesToLoad);
                });

                it("should be up-to-date with newly created files", () => {
                    const { moduleFile1, files, verifyProjectsUpdatedInBackgroundEvent, } = getInitialState();

                    const file1Consumer3: File = {
                        path: "/a/b/file1Consumer3.ts",
                        content: `import {Foo} from "./moduleFile1"; let y = Foo();`
                    };
                    moduleFile1.content = `export var T: number;export function Foo() { };`;
                    verifyProjectsUpdatedInBackgroundEvent(files.concat(file1Consumer3));
                });

                it("should detect changes in non-root files", () => {
                    const { moduleFile1, verifyProjectsUpdatedInBackgroundEvent } = getInitialState({
                        configObj: { files: [file1Consumer1Path] },
                    });

                    moduleFile1.content = `export var T: number;export function Foo() { };`;
                    verifyProjectsUpdatedInBackgroundEvent();

                    // change file1 internal, and verify only file1 is affected
                    moduleFile1.content += "var T1: number;";
                    verifyProjectsUpdatedInBackgroundEvent();
                });

                it("should return all files if a global file changed shape", () => {
                    const { globalFile3, verifyProjectsUpdatedInBackgroundEvent } = getInitialState();

                    globalFile3.content += "var T2: string;";
                    verifyProjectsUpdatedInBackgroundEvent();
                });

                it("should always return the file itself if '--isolatedModules' is specified", () => {
                    const { moduleFile1, verifyProjectsUpdatedInBackgroundEvent } = getInitialState({
                        configObj: { compilerOptions: { isolatedModules: true } }
                    });

                    moduleFile1.content = `export var T: number;export function Foo() { };`;
                    verifyProjectsUpdatedInBackgroundEvent();
                });

                it("should always return the file itself if '--out' or '--outFile' is specified", () => {
                    const outFilePath = "/a/b/out.js";
                    const { moduleFile1, verifyProjectsUpdatedInBackgroundEvent } = getInitialState({
                        configObj: { compilerOptions: { module: "system", outFile: outFilePath } }
                    });

                    moduleFile1.content = `export var T: number;export function Foo() { };`;
                    verifyProjectsUpdatedInBackgroundEvent();
                });

                it("should return cascaded affected file list", () => {
                    const file1Consumer1Consumer1: File = {
                        path: "/a/b/file1Consumer1Consumer1.ts",
                        content: `import {y} from "./file1Consumer1";`
                    };
                    const { moduleFile1, file1Consumer1, updateContentOfOpenFile, verifyNoProjectsUpdatedInBackgroundEvent, verifyProjectsUpdatedInBackgroundEvent } = getInitialState({
                        getAdditionalFileOrFolder: () => [file1Consumer1Consumer1]
                    });

                    updateContentOfOpenFile(file1Consumer1, file1Consumer1.content + "export var T: number;");
                    verifyNoProjectsUpdatedInBackgroundEvent();

                    // Doesnt change the shape of file1Consumer1
                    moduleFile1.content = `export var T: number;export function Foo() { };`;
                    verifyProjectsUpdatedInBackgroundEvent();

                    // Change both files before the timeout
                    updateContentOfOpenFile(file1Consumer1, file1Consumer1.content + "export var T2: number;");
                    moduleFile1.content = `export var T2: number;export function Foo() { };`;
                    verifyProjectsUpdatedInBackgroundEvent();
                });

                it("should work fine for files with circular references", () => {
                    const file1: File = {
                        path: "/a/b/file1.ts",
                        content: `
                    /// <reference path="./file2.ts" />
                    export var t1 = 10;`
                    };
                    const file2: File = {
                        path: "/a/b/file2.ts",
                        content: `
                    /// <reference path="./file1.ts" />
                    export var t2 = 10;`
                    };
                    const { configFile, verifyProjectsUpdatedInBackgroundEvent } = getInitialState({
                        getAdditionalFileOrFolder: () => [file1, file2],
                        firstReloadFileList: [file1.path, libFile.path, file2.path, configFilePath]
                    });

                    file2.content += "export var t3 = 10;";
                    verifyProjectsUpdatedInBackgroundEvent([file1, file2, libFile, configFile]);
                });

                it("should detect removed code file", () => {
                    const referenceFile1: File = {
                        path: "/a/b/referenceFile1.ts",
                        content: `
                    /// <reference path="./moduleFile1.ts" />
                    export var x = Foo();`
                    };
                    const { configFile, verifyProjectsUpdatedInBackgroundEvent } = getInitialState({
                        getAdditionalFileOrFolder: () => [referenceFile1],
                        firstReloadFileList: [referenceFile1.path, libFile.path, moduleFile1Path, configFilePath]
                    });

                    verifyProjectsUpdatedInBackgroundEvent([libFile, referenceFile1, configFile]);
                });

                it("should detect non-existing code file", () => {
                    const referenceFile1: File = {
                        path: "/a/b/referenceFile1.ts",
                        content: `
                    /// <reference path="./moduleFile2.ts" />
                    export var x = Foo();`
                    };
                    const { configFile, moduleFile2, updateContentOfOpenFile, verifyNoProjectsUpdatedInBackgroundEvent, verifyProjectsUpdatedInBackgroundEvent } = getInitialState({
                        getAdditionalFileOrFolder: () => [referenceFile1],
                        firstReloadFileList: [referenceFile1.path, libFile.path, configFilePath]
                    });

                    updateContentOfOpenFile(referenceFile1, referenceFile1.content + "export var yy = Foo();");
                    verifyNoProjectsUpdatedInBackgroundEvent([libFile, referenceFile1, configFile]);

                    // Create module File2 and see both files are saved
                    verifyProjectsUpdatedInBackgroundEvent([libFile, moduleFile2, referenceFile1, configFile]);
                });
            });

            describe("resolution when resolution cache size", () => {
                function verifyWithMaxCacheLimit(limitHit: boolean, useSlashRootAsSomeNotRootFolderInUserDirectory: boolean) {
                    const rootFolder = useSlashRootAsSomeNotRootFolderInUserDirectory ? "/user/username/rootfolder/otherfolder/" : "/";
                    const file1: File = {
                        path: rootFolder + "a/b/project/file1.ts",
                        content: 'import a from "file2"'
                    };
                    const file2: File = {
                        path: rootFolder + "a/b/node_modules/file2.d.ts",
                        content: "export class a { }"
                    };
                    const file3: File = {
                        path: rootFolder + "a/b/project/file3.ts",
                        content: "export class c { }"
                    };
                    const configFile: File = {
                        path: rootFolder + "a/b/project/tsconfig.json",
                        content: JSON.stringify({ compilerOptions: { typeRoots: [] } })
                    };

                    const projectFiles = [file1, file3, libFile, configFile];
                    const openFiles = [file1.path];
                    const watchedRecursiveDirectories = useSlashRootAsSomeNotRootFolderInUserDirectory ?
                        // Folders of node_modules lookup not in changedRoot
                        ["a/b/project", "a/b/node_modules", "a/node_modules", "node_modules"].map(v => rootFolder + v) :
                        // Folder of tsconfig
                        ["/a/b/project"];
                    const host = createServerHost(projectFiles);
                    const { session, verifyInitialOpen, verifyProjectsUpdatedInBackgroundEventHandler } = createSession(host);
                    const projectService = session.getProjectService();
                    verifyInitialOpen(file1);
                    checkNumberOfProjects(projectService, { configuredProjects: 1 });
                    const project = projectService.configuredProjects.get(configFile.path)!;
                    verifyProject();
                    if (limitHit) {
                        (project as ResolutionCacheHost).maxNumberOfFilesToIterateForInvalidation = 1;
                    }

                    file3.content += "export class d {}";
                    host.reloadFS(projectFiles);
                    host.checkTimeoutQueueLengthAndRun(2);

                    // Since this is first event
                    verifyProject();
                    verifyProjectsUpdatedInBackgroundEventHandler([{
                        eventName: server.ProjectsUpdatedInBackgroundEvent,
                        data: {
                            openFiles
                        }
                    }]);

                    projectFiles.push(file2);
                    host.reloadFS(projectFiles);
                    host.runQueuedTimeoutCallbacks();
                    if (useSlashRootAsSomeNotRootFolderInUserDirectory) {
                        watchedRecursiveDirectories.length = 2;
                    }
                    else {
                        // file2 addition wont be detected
                        projectFiles.pop();
                        assert.isTrue(host.fileExists(file2.path));
                    }
                    verifyProject();

                    verifyProjectsUpdatedInBackgroundEventHandler(useSlashRootAsSomeNotRootFolderInUserDirectory ? [{
                        eventName: server.ProjectsUpdatedInBackgroundEvent,
                        data: {
                            openFiles
                        }
                    }] : []);

                    function verifyProject() {
                        checkProjectActualFiles(project, map(projectFiles, file => file.path));
                        checkWatchedDirectories(host, [], /*recursive*/ false);
                        checkWatchedDirectories(host, watchedRecursiveDirectories, /*recursive*/ true);
                    }
                }

                it("limit not hit and project is not at root level", () => {
                    verifyWithMaxCacheLimit(/*limitHit*/ false, /*useSlashRootAsSomeNotRootFolderInUserDirectory*/ true);
                });

                it("limit hit and project is not at root level", () => {
                    verifyWithMaxCacheLimit(/*limitHit*/ true, /*useSlashRootAsSomeNotRootFolderInUserDirectory*/ true);
                });

                it("limit not hit and project is at root level", () => {
                    verifyWithMaxCacheLimit(/*limitHit*/ false, /*useSlashRootAsSomeNotRootFolderInUserDirectory*/ false);
                });

                it("limit hit and project is at root level", () => {
                    verifyWithMaxCacheLimit(/*limitHit*/ true, /*useSlashRootAsSomeNotRootFolderInUserDirectory*/ false);
                });
            });
        }

        describe("when event handler is set in the session", () => {
            verifyProjectsUpdatedInBackgroundEvent(createSessionWithProjectChangedEventHandler);

            function createSessionWithProjectChangedEventHandler(host: TestServerHost): ProjectsUpdatedInBackgroundEventVerifier {
                const projectChangedEvents: server.ProjectsUpdatedInBackgroundEvent[] = [];
                const session = createSession(host, {
                    eventHandler: e => {
                        if (e.eventName === server.ProjectsUpdatedInBackgroundEvent) {
                            projectChangedEvents.push(e);
                        }
                    }
                });

                return {
                    session,
                    verifyProjectsUpdatedInBackgroundEventHandler,
                    verifyInitialOpen: createVerifyInitialOpen(session, verifyProjectsUpdatedInBackgroundEventHandler)
                };

                function eventToString(event: server.ProjectsUpdatedInBackgroundEvent) {
                    return JSON.stringify(event && { eventName: event.eventName, data: event.data });
                }

                function eventsToString(events: ReadonlyArray<server.ProjectsUpdatedInBackgroundEvent>) {
                    return "[" + map(events, eventToString).join(",") + "]";
                }

                function verifyProjectsUpdatedInBackgroundEventHandler(expectedEvents: ReadonlyArray<server.ProjectsUpdatedInBackgroundEvent>) {
                    assert.equal(projectChangedEvents.length, expectedEvents.length, `Incorrect number of events Actual: ${eventsToString(projectChangedEvents)} Expected: ${eventsToString(expectedEvents)}`);
                    forEach(projectChangedEvents, (actualEvent, i) => {
                        const expectedEvent = expectedEvents[i];
                        assert.strictEqual(actualEvent.eventName, expectedEvent.eventName);
                        verifyFiles("openFiles", actualEvent.data.openFiles, expectedEvent.data.openFiles);
                    });

                    // Verified the events, reset them
                    projectChangedEvents.length = 0;
                }
            }
        });

        describe("when event handler is not set but session is created with canUseEvents = true", () => {
            describe("without noGetErrOnBackgroundUpdate, diagnostics for open files are queued", () => {
                verifyProjectsUpdatedInBackgroundEvent(createSessionThatUsesEvents);
            });

            describe("with noGetErrOnBackgroundUpdate, diagnostics for open file are not queued", () => {
                verifyProjectsUpdatedInBackgroundEvent(host => createSessionThatUsesEvents(host, /*noGetErrOnBackgroundUpdate*/ true));
            });


            function createSessionThatUsesEvents(host: TestServerHost, noGetErrOnBackgroundUpdate?: boolean): ProjectsUpdatedInBackgroundEventVerifier {
                const session = createSession(host, { canUseEvents: true, noGetErrOnBackgroundUpdate });

                return {
                    session,
                    verifyProjectsUpdatedInBackgroundEventHandler,
                    verifyInitialOpen: createVerifyInitialOpen(session, verifyProjectsUpdatedInBackgroundEventHandler)
                };

                function verifyProjectsUpdatedInBackgroundEventHandler(expected: ReadonlyArray<server.ProjectsUpdatedInBackgroundEvent>) {
                    const expectedEvents: protocol.ProjectsUpdatedInBackgroundEventBody[] = map(expected, e => {
                        return {
                            openFiles: e.data.openFiles
                        };
                    });
                    const outputEventRegex = /Content\-Length: [\d]+\r\n\r\n/;
                    const events: protocol.ProjectsUpdatedInBackgroundEvent[] = filter(
                        map(
                            host.getOutput(), s => convertToObject(
                                parseJsonText("json.json", s.replace(outputEventRegex, "")),
                                []
                            )
                        ),
                        e => e.event === server.ProjectsUpdatedInBackgroundEvent
                    );
                    assert.equal(events.length, expectedEvents.length, `Incorrect number of events Actual: ${map(events, e => e.body)} Expected: ${expectedEvents}`);
                    forEach(events, (actualEvent, i) => {
                        const expectedEvent = expectedEvents[i];
                        verifyFiles("openFiles", actualEvent.body.openFiles, expectedEvent.openFiles);
                    });

                    // Verified the events, reset them
                    session.clearMessages();

                    if (events.length) {
                        host.checkTimeoutQueueLength(noGetErrOnBackgroundUpdate ? 0 : 1); // Error checking queued only if not noGetErrOnBackgroundUpdate
                    }
                }
            }
        });
    });

    describe("tsserverProjectSystem Watched recursive directories with windows style file system", () => {
        function verifyWatchedDirectories(rootedPath: string, useProjectAtRoot: boolean) {
            const root = useProjectAtRoot ? rootedPath : `${rootedPath}myfolder/allproject/`;
            const configFile: File = {
                path: root + "project/tsconfig.json",
                content: "{}"
            };
            const file1: File = {
                path: root + "project/file1.ts",
                content: "let x = 10;"
            };
            const file2: File = {
                path: root + "project/file2.ts",
                content: "let y = 10;"
            };
            const files = [configFile, file1, file2, libFile];
            const host = createServerHost(files, { useWindowsStylePaths: true });
            const projectService = createProjectService(host);
            projectService.openClientFile(file1.path);
            const project = projectService.configuredProjects.get(configFile.path)!;
            assert.isDefined(project);
            const winsowsStyleLibFilePath = "c:/" + libFile.path.substring(1);
            checkProjectActualFiles(project, files.map(f => f === libFile ? winsowsStyleLibFilePath : f.path));
            checkWatchedFiles(host, mapDefined(files, f => f === libFile ? winsowsStyleLibFilePath : f === file1 ? undefined : f.path));
            checkWatchedDirectories(host, [], /*recursive*/ false);
            checkWatchedDirectories(host, [
                root + "project",
                root + "project/node_modules/@types"
            ].concat(useProjectAtRoot ? [] : [root + nodeModulesAtTypes]), /*recursive*/ true);
        }

        function verifyRootedDirectoryWatch(rootedPath: string) {
            it("When project is in rootFolder of style c:/", () => {
                verifyWatchedDirectories(rootedPath, /*useProjectAtRoot*/ true);
            });

            it("When files at some folder other than root", () => {
                verifyWatchedDirectories(rootedPath, /*useProjectAtRoot*/ false);
            });
        }

        describe("for rootFolder of style c:/", () => {
            verifyRootedDirectoryWatch("c:/");
        });

        describe("for rootFolder of style c:/users/username", () => {
            verifyRootedDirectoryWatch("c:/users/username/");
        });
    });

    describe("tsserverProjectSystem typingsInstaller on inferred Project", () => {
        it("when projectRootPath is provided", () => {
            const projects = "/users/username/projects";
            const projectRootPath = `${projects}/san2`;
            const file: File = {
                path: `${projectRootPath}/x.js`,
                content: "const aaaaaaav = 1;"
            };

            const currentDirectory = `${projects}/anotherProject`;
            const packageJsonInCurrentDirectory: File = {
                path: `${currentDirectory}/package.json`,
                content: JSON.stringify({
                    devDependencies: {
                        pkgcurrentdirectory: ""
                    },
                })
            };
            const packageJsonOfPkgcurrentdirectory: File = {
                path: `${currentDirectory}/node_modules/pkgcurrentdirectory/package.json`,
                content: JSON.stringify({
                    name: "pkgcurrentdirectory",
                    main: "index.js",
                    typings: "index.d.ts"
                })
            };
            const indexOfPkgcurrentdirectory: File = {
                path: `${currentDirectory}/node_modules/pkgcurrentdirectory/index.d.ts`,
                content: "export function foo() { }"
            };

            const typingsCache = `/users/username/Library/Caches/typescript/2.7`;
            const typingsCachePackageJson: File = {
                path: `${typingsCache}/package.json`,
                content: JSON.stringify({
                    devDependencies: {
                    },
                })
            };
            const typingsCachePackageLockJson: File = {
                path: `${typingsCache}/package-lock.json`,
                content: JSON.stringify({
                    dependencies: {
                    },
                })
            };

            const files = [file, packageJsonInCurrentDirectory, packageJsonOfPkgcurrentdirectory, indexOfPkgcurrentdirectory, typingsCachePackageJson, typingsCachePackageLockJson];
            const host = createServerHost(files, { currentDirectory });

            const typesRegistry = createTypesRegistry("pkgcurrentdirectory");
            const typingsInstaller = new TestTypingsInstaller(typingsCache, /*throttleLimit*/ 5, host, typesRegistry);

            const projectService = createProjectService(host, { typingsInstaller });

            projectService.setCompilerOptionsForInferredProjects({
                module: ModuleKind.CommonJS,
                target: ScriptTarget.ES2016,
                jsx: JsxEmit.Preserve,
                experimentalDecorators: true,
                allowJs: true,
                allowSyntheticDefaultImports: true,
                allowNonTsExtensions: true
            });

            projectService.openClientFile(file.path, file.content, ScriptKind.JS, projectRootPath);

            const project = projectService.inferredProjects[0];
            assert.isDefined(project);

            // Ensure that we use result from types cache when getting ls
            assert.isDefined(project.getLanguageService());

            // Verify that the pkgcurrentdirectory from the current directory isnt picked up
            checkProjectActualFiles(project, [file.path]);
        });
    });

    describe("tsserverProjectSystem with symLinks", () => {
        it("rename in common file renames all project", () => {
            const projects = "/users/username/projects";
            const folderA = `${projects}/a`;
            const aFile: File = {
                path: `${folderA}/a.ts`,
                content: `import {C} from "./c/fc"; console.log(C)`
            };
            const aTsconfig: File = {
                path: `${folderA}/tsconfig.json`,
                content: JSON.stringify({ compilerOptions: { module: "commonjs" } })
            };
            const aC: SymLink = {
                path: `${folderA}/c`,
                symLink: "../c"
            };
            const aFc = `${folderA}/c/fc.ts`;

            const folderB = `${projects}/b`;
            const bFile: File = {
                path: `${folderB}/b.ts`,
                content: `import {C} from "./c/fc"; console.log(C)`
            };
            const bTsconfig: File = {
                path: `${folderB}/tsconfig.json`,
                content: JSON.stringify({ compilerOptions: { module: "commonjs" } })
            };
            const bC: SymLink = {
                path: `${folderB}/c`,
                symLink: "../c"
            };
            const bFc = `${folderB}/c/fc.ts`;

            const folderC = `${projects}/c`;
            const cFile: File = {
                path: `${folderC}/fc.ts`,
                content: `export const C = 8`
            };

            const files = [cFile, libFile, aFile, aTsconfig, aC, bFile, bTsconfig, bC];
            const host = createServerHost(files);
            const session = createSession(host);
            const projectService = session.getProjectService();
            openFilesForSession(
                [
                    { file: aFile, projectRootPath: folderA },
                    { file: bFile, projectRootPath: folderB },
                    { file: aFc, projectRootPath: folderA },
                    { file: bFc, projectRootPath: folderB },
                ],
                session);
            checkNumberOfProjects(projectService, { configuredProjects: 2 });
            assert.isDefined(projectService.configuredProjects.get(aTsconfig.path));
            assert.isDefined(projectService.configuredProjects.get(bTsconfig.path));

            const response = executeSessionRequest<protocol.RenameRequest, protocol.RenameResponse>(session, protocol.CommandTypes.Rename, { file: aFc, ...protocolLocationFromSubstring(cFile.content, "C") });

            assert.equal(aFile.content, bFile.content);
            const abLocs: protocol.TextSpan[] = [
                protocolTextSpanFromSubstring(aFile.content, "C"),
                protocolTextSpanFromSubstring(aFile.content, "C", { index: 1 }),
            ];
            const cLocs: protocol.TextSpan[] = [protocolTextSpanFromSubstring(cFile.content, "C")];
            assert.deepEqual<protocol.RenameResponseBody | undefined>(response, {
                info: {
                    canRename: true,
                    displayName: "C",
                    fullDisplayName: '"/users/username/projects/a/c/fc".C',
                    kind: ScriptElementKind.constElement,
                    kindModifiers: ScriptElementKindModifier.exportedModifier,
                    localizedErrorMessage: undefined,
                },
                locs: [
                    { file: aFc, locs: cLocs },
                    { file: aFile.path, locs: abLocs },
                    { file: bFc, locs: cLocs },
                    { file: bFile.path, locs: abLocs },
                ],
            });
        });

        describe("module resolution when symlinked folder contents change and resolve modules", () => {
            const projectRootPath = "/users/username/projects/myproject";
            const packages = `${projectRootPath}/javascript/packages`;
            const recognizersDateTime = `${packages}/recognizers-date-time`;
            const recognizersText = `${packages}/recognizers-text`;
            const recognizersTextDist = `${recognizersText}/dist`;
            const moduleName = "@microsoft/recognizers-text";
            const moduleNameInFile = `"${moduleName}"`;
            const recognizersDateTimeSrcFile: File = {
                path: `${recognizersDateTime}/src/datetime/baseDate.ts`,
                content: `import {C} from ${moduleNameInFile};
new C();`
            };
            const recognizerDateTimeTsconfigPath = `${recognizersDateTime}/tsconfig.json`;
            const recognizerDateTimeTsconfigWithoutPathMapping: File = {
                path: recognizerDateTimeTsconfigPath,
                content: JSON.stringify({
                    include: ["src"]
                })
            };
            const recognizerDateTimeTsconfigWithPathMapping: File = {
                path: recognizerDateTimeTsconfigPath,
                content: JSON.stringify({
                    compilerOptions: {
                        rootDir: "src",
                        baseUrl: "./",
                        paths: {
                            "@microsoft/*": ["../*"]
                        }
                    },
                    include: ["src"]
                })
            };
            const nodeModulesRecorgnizersText: SymLink = {
                path: `${recognizersDateTime}/node_modules/@microsoft/recognizers-text`,
                symLink: recognizersText
            };
            const recognizerTextSrcFile: File = {
                path: `${recognizersText}/src/recognizers-text.ts`,
                content: `export class C { method () { return 10; } }`
            };
            const recongnizerTextDistTypingFile: File = {
                path: `${recognizersTextDist}/types/recognizers-text.d.ts`,
                content: `export class C { method(): number; }`
            };
            const recongnizerTextPackageJson: File = {
                path: `${recognizersText}/package.json`,
                content: JSON.stringify({
                    typings: "dist/types/recognizers-text.d.ts"
                })
            };
            const filesInProjectWithUnresolvedModule = [recognizerDateTimeTsconfigPath, libFile.path, recognizersDateTimeSrcFile.path];
            const filesInProjectWithResolvedModule = [...filesInProjectWithUnresolvedModule, recongnizerTextDistTypingFile.path];

            function verifyErrors(session: TestSession, semanticErrors: protocol.Diagnostic[]) {
                session.clearMessages();
                const expectedSequenceId = session.getNextSeq();
                session.executeCommandSeq<protocol.GeterrRequest>({
                    command: server.CommandNames.Geterr,
                    arguments: {
                        delay: 0,
                        files: [recognizersDateTimeSrcFile.path],
                    }
                });

                const host = session.host;
                host.checkTimeoutQueueLengthAndRun(1);

                checkErrorMessage(session, "syntaxDiag", { file: recognizersDateTimeSrcFile.path, diagnostics: [] });
                session.clearMessages();

                host.runQueuedImmediateCallbacks(1);

                checkErrorMessage(session, "semanticDiag", { file: recognizersDateTimeSrcFile.path, diagnostics: semanticErrors });
                session.clearMessages();

                host.runQueuedImmediateCallbacks(1);

                checkErrorMessage(session, "suggestionDiag", {
                    file: recognizersDateTimeSrcFile.path,
                    diagnostics: [],
                });
                checkCompleteEvent(session, 2, expectedSequenceId);
            }

            function verifyWatchedFilesAndDirectories(host: TestServerHost, files: string[], recursiveDirectories: string[], nonRecursiveDirectories: string[]) {
                checkWatchedFilesDetailed(host, files.filter(f => f !== recognizersDateTimeSrcFile.path), 1);
                checkWatchedDirectoriesDetailed(host, nonRecursiveDirectories, 1,  /*recursive*/ false);
                checkWatchedDirectoriesDetailed(host, recursiveDirectories, 1, /*recursive*/ true);
            }

            function createSessionAndOpenFile(host: TestServerHost) {
                const session = createSession(host, { canUseEvents: true });
                session.executeCommandSeq<protocol.OpenRequest>({
                    command: protocol.CommandTypes.Open,
                    arguments: {
                        file: recognizersDateTimeSrcFile.path,
                        projectRootPath
                    }
                });
                return session;
            }

            function verifyModuleResolution(withPathMapping: boolean) {
                describe(withPathMapping ? "when tsconfig file contains path mapping" : "when tsconfig does not contain path mapping", () => {
                    const filesWithSources = [libFile, recognizersDateTimeSrcFile, withPathMapping ? recognizerDateTimeTsconfigWithPathMapping : recognizerDateTimeTsconfigWithoutPathMapping, recognizerTextSrcFile, recongnizerTextPackageJson];
                    const filesWithNodeModulesSetup = [...filesWithSources, nodeModulesRecorgnizersText];
                    const filesAfterCompilation = [...filesWithNodeModulesSetup, recongnizerTextDistTypingFile];

                    const watchedDirectoriesWithResolvedModule = [`${recognizersDateTime}/src`, ...(withPathMapping ? emptyArray : [recognizersDateTime]), ...getTypeRootsFromLocation(recognizersDateTime)];
                    const watchedDirectoriesWithUnresolvedModule = [recognizersDateTime, ...(withPathMapping ? [recognizersText] : emptyArray), ...watchedDirectoriesWithResolvedModule, ...getNodeModuleDirectories(packages)];
                    const nonRecursiveWatchedDirectories = withPathMapping ? [packages] : emptyArray;

                    function verifyProjectWithResolvedModule(session: TestSession) {
                        const projectService = session.getProjectService();
                        const project = projectService.configuredProjects.get(recognizerDateTimeTsconfigPath)!;
                        checkProjectActualFiles(project, filesInProjectWithResolvedModule);
                        verifyWatchedFilesAndDirectories(session.host, filesInProjectWithResolvedModule, watchedDirectoriesWithResolvedModule, nonRecursiveWatchedDirectories);
                        verifyErrors(session, []);
                    }

                    function verifyProjectWithUnresolvedModule(session: TestSession) {
                        const projectService = session.getProjectService();
                        const project = projectService.configuredProjects.get(recognizerDateTimeTsconfigPath)!;
                        checkProjectActualFiles(project, filesInProjectWithUnresolvedModule);
                        verifyWatchedFilesAndDirectories(session.host, filesInProjectWithUnresolvedModule, watchedDirectoriesWithUnresolvedModule, nonRecursiveWatchedDirectories);
                        const startOffset = recognizersDateTimeSrcFile.content.indexOf('"') + 1;
                        verifyErrors(session, [
                            createDiagnostic({ line: 1, offset: startOffset }, { line: 1, offset: startOffset + moduleNameInFile.length }, Diagnostics.Cannot_find_module_0, [moduleName])
                        ]);
                    }

                    it("when project compiles from sources", () => {
                        const host = createServerHost(filesWithSources);
                        const session = createSessionAndOpenFile(host);
                        verifyProjectWithUnresolvedModule(session);

                        host.reloadFS(filesAfterCompilation);
                        host.runQueuedTimeoutCallbacks();

                        verifyProjectWithResolvedModule(session);
                    });

                    it("when project has node_modules setup but doesnt have modules in typings folder and then recompiles", () => {
                        const host = createServerHost(filesWithNodeModulesSetup);
                        const session = createSessionAndOpenFile(host);
                        verifyProjectWithUnresolvedModule(session);

                        host.reloadFS(filesAfterCompilation);
                        host.runQueuedTimeoutCallbacks();

                        if (withPathMapping) {
                            verifyProjectWithResolvedModule(session);
                        }
                        else {
                            // Cannot handle the resolution update
                            verifyProjectWithUnresolvedModule(session);
                        }
                    });

                    it("when project recompiles after deleting generated folders", () => {
                        const host = createServerHost(filesAfterCompilation);
                        const session = createSessionAndOpenFile(host);

                        verifyProjectWithResolvedModule(session);

                        host.removeFolder(recognizersTextDist, /*recursive*/ true);
                        host.runQueuedTimeoutCallbacks();

                        verifyProjectWithUnresolvedModule(session);

                        host.ensureFileOrFolder(recongnizerTextDistTypingFile);
                        host.runQueuedTimeoutCallbacks();

                        if (withPathMapping) {
                            verifyProjectWithResolvedModule(session);
                        }
                        else {
                            // Cannot handle the resolution update
                            verifyProjectWithUnresolvedModule(session);
                        }
                    });
                });
            }

            verifyModuleResolution(/*withPathMapping*/ false);
            verifyModuleResolution(/*withPathMapping*/ true);
        });
    });

    describe("tsserverProjectSystem forceConsistentCasingInFileNames", () => {
        it("works when extends is specified with a case insensitive file system", () => {
            const rootPath = "/Users/username/dev/project";
            const file1: File = {
                path: `${rootPath}/index.ts`,
                content: 'import {x} from "file2";',
            };
            const file2: File = {
                path: `${rootPath}/file2.js`,
                content: "",
            };
            const file2Dts: File = {
                path: `${rootPath}/types/file2/index.d.ts`,
                content: "export declare const x: string;",
            };
            const tsconfigAll: File = {
                path: `${rootPath}/tsconfig.all.json`,
                content: JSON.stringify({
                    compilerOptions: {
                        baseUrl: ".",
                        paths: { file2: ["./file2.js"] },
                        typeRoots: ["./types"],
                        forceConsistentCasingInFileNames: true,
                    },
                }),
            };
            const tsconfig: File = {
                path: `${rootPath}/tsconfig.json`,
                content: JSON.stringify({ extends: "./tsconfig.all.json" }),
            };

            const host = createServerHost([file1, file2, file2Dts, libFile, tsconfig, tsconfigAll], { useCaseSensitiveFileNames: false });
            const session = createSession(host);

            openFilesForSession([file1], session);
            const projectService = session.getProjectService();

            checkNumberOfProjects(projectService, { configuredProjects: 1 });

            const diagnostics = configuredProjectAt(projectService, 0).getLanguageService().getCompilerOptionsDiagnostics();
            assert.deepEqual(diagnostics, []);
        });
    });

    describe("tsserverProjectSystem module resolution caching", () => {
        const projectLocation = "/user/username/projects/myproject";
        const configFile: File = {
            path: `${projectLocation}/tsconfig.json`,
            content: JSON.stringify({ compilerOptions: { traceResolution: true } })
        };

        function getModules(module1Path: string, module2Path: string) {
            const module1: File = {
                path: module1Path,
                content: `export function module1() {}`
            };
            const module2: File = {
                path: module2Path,
                content: `export function module2() {}`
            };
            return { module1, module2 };
        }

        function verifyTrace(resolutionTrace: string[], expected: string[]) {
            assert.deepEqual(resolutionTrace, expected);
            resolutionTrace.length = 0;
        }

        function getExpectedFileDoesNotExistResolutionTrace(host: TestServerHost, expectedTrace: string[], foundModule: boolean, module: File, directory: string, file: string, ignoreIfParentMissing?: boolean) {
            if (!foundModule) {
                const path = combinePaths(directory, file);
                if (!ignoreIfParentMissing || host.directoryExists(getDirectoryPath(path))) {
                    if (module.path === path) {
                        foundModule = true;
                    }
                    else {
                        expectedTrace.push(`File '${path}' does not exist.`);
                    }
                }
            }
            return foundModule;
        }

        function getExpectedMissedLocationResolutionTrace(host: TestServerHost, expectedTrace: string[], dirPath: string, module: File, moduleName: string, useNodeModules: boolean, cacheLocation?: string) {
            let foundModule = false;
            forEachAncestorDirectory(dirPath, dirPath => {
                if (dirPath === cacheLocation) {
                    return foundModule;
                }

                const directory = useNodeModules ? combinePaths(dirPath, nodeModules) : dirPath;
                if (useNodeModules && !foundModule && !host.directoryExists(directory)) {
                    expectedTrace.push(`Directory '${directory}' does not exist, skipping all lookups in it.`);
                    return undefined;
                }
                foundModule = getExpectedFileDoesNotExistResolutionTrace(host, expectedTrace, foundModule, module, directory, `${moduleName}/package.json`, /*ignoreIfParentMissing*/ true);
                foundModule = getExpectedFileDoesNotExistResolutionTrace(host, expectedTrace, foundModule, module, directory, `${moduleName}.ts`);
                foundModule = getExpectedFileDoesNotExistResolutionTrace(host, expectedTrace, foundModule, module, directory, `${moduleName}.tsx`);
                foundModule = getExpectedFileDoesNotExistResolutionTrace(host, expectedTrace, foundModule, module, directory, `${moduleName}.d.ts`);
                foundModule = getExpectedFileDoesNotExistResolutionTrace(host, expectedTrace, foundModule, module, directory, `${moduleName}/index.ts`, /*ignoreIfParentMissing*/ true);
                if (useNodeModules && !foundModule) {
                    expectedTrace.push(`Directory '${directory}/@types' does not exist, skipping all lookups in it.`);
                }
                return foundModule ? true : undefined;
            });
        }

        function getExpectedResolutionTraceHeader(expectedTrace: string[], file: File, moduleName: string) {
            expectedTrace.push(
                `======== Resolving module '${moduleName}' from '${file.path}'. ========`,
                `Module resolution kind is not specified, using 'NodeJs'.`
            );
        }

        function getExpectedResolutionTraceFooter(expectedTrace: string[], module: File, moduleName: string, addRealPathTrace: boolean, ignoreModuleFileFound?: boolean) {
            if (!ignoreModuleFileFound) {
                expectedTrace.push(`File '${module.path}' exist - use it as a name resolution result.`);
            }
            if (addRealPathTrace) {
                expectedTrace.push(`Resolving real path for '${module.path}', result '${module.path}'.`);
            }
            expectedTrace.push(`======== Module name '${moduleName}' was successfully resolved to '${module.path}'. ========`);
        }

        function getExpectedRelativeModuleResolutionTrace(host: TestServerHost, file: File, module: File, moduleName: string, expectedTrace: string[] = []) {
            getExpectedResolutionTraceHeader(expectedTrace, file, moduleName);
            expectedTrace.push(`Loading module as file / folder, candidate module location '${removeFileExtension(module.path)}', target file type 'TypeScript'.`);
            getExpectedMissedLocationResolutionTrace(host, expectedTrace, getDirectoryPath(normalizePath(combinePaths(getDirectoryPath(file.path), moduleName))), module, moduleName.substring(moduleName.lastIndexOf("/") + 1), /*useNodeModules*/ false);
            getExpectedResolutionTraceFooter(expectedTrace, module, moduleName, /*addRealPathTrace*/ false);
            return expectedTrace;
        }

        function getExpectedNonRelativeModuleResolutionTrace(host: TestServerHost, file: File, module: File, moduleName: string, expectedTrace: string[] = []) {
            getExpectedResolutionTraceHeader(expectedTrace, file, moduleName);
            expectedTrace.push(`Loading module '${moduleName}' from 'node_modules' folder, target file type 'TypeScript'.`);
            getExpectedMissedLocationResolutionTrace(host, expectedTrace, getDirectoryPath(file.path), module, moduleName, /*useNodeModules*/ true);
            getExpectedResolutionTraceFooter(expectedTrace, module, moduleName, /*addRealPathTrace*/ true);
            return expectedTrace;
        }

        function getExpectedNonRelativeModuleResolutionFromCacheTrace(host: TestServerHost, file: File, module: File, moduleName: string, cacheLocation: string, expectedTrace: string[] = []) {
            getExpectedResolutionTraceHeader(expectedTrace, file, moduleName);
            expectedTrace.push(`Loading module '${moduleName}' from 'node_modules' folder, target file type 'TypeScript'.`);
            getExpectedMissedLocationResolutionTrace(host, expectedTrace, getDirectoryPath(file.path), module, moduleName, /*useNodeModules*/ true, cacheLocation);
            expectedTrace.push(`Resolution for module '${moduleName}' was found in cache from location '${cacheLocation}'.`);
            getExpectedResolutionTraceFooter(expectedTrace, module, moduleName, /*addRealPathTrace*/ true, /*ignoreModuleFileFound*/ true);
            return expectedTrace;
        }

        function getExpectedReusingResolutionFromOldProgram(file: File, moduleName: string) {
            return `Reusing resolution of module '${moduleName}' to file '${file.path}' from old program.`;
        }

        function verifyWatchesWithConfigFile(host: TestServerHost, files: File[], openFile: File) {
            checkWatchedFiles(host, mapDefined(files, f => f === openFile ? undefined : f.path));
            checkWatchedDirectories(host, [], /*recursive*/ false);
            const configDirectory = getDirectoryPath(configFile.path);
            checkWatchedDirectories(host, [configDirectory, `${configDirectory}/${nodeModulesAtTypes}`], /*recursive*/ true);
        }

        describe("from files in same folder", () => {
            function getFiles(fileContent: string) {
                const file1: File = {
                    path: `${projectLocation}/src/file1.ts`,
                    content: fileContent
                };
                const file2: File = {
                    path: `${projectLocation}/src/file2.ts`,
                    content: fileContent
                };
                return { file1, file2 };
            }

            it("relative module name", () => {
                const module1Name = "./module1";
                const module2Name = "../module2";
                const fileContent = `import { module1 } from "${module1Name}";import { module2 } from "${module2Name}";`;
                const { file1, file2 } = getFiles(fileContent);
                const { module1, module2 } = getModules(`${projectLocation}/src/module1.ts`, `${projectLocation}/module2.ts`);
                const files = [module1, module2, file1, file2, configFile, libFile];
                const host = createServerHost(files);
                const resolutionTrace = createHostModuleResolutionTrace(host);
                const service = createProjectService(host);
                service.openClientFile(file1.path);
                const expectedTrace = getExpectedRelativeModuleResolutionTrace(host, file1, module1, module1Name);
                getExpectedRelativeModuleResolutionTrace(host, file1, module2, module2Name, expectedTrace);
                verifyTrace(resolutionTrace, expectedTrace);
                verifyWatchesWithConfigFile(host, files, file1);

                file1.content += fileContent;
                file2.content += fileContent;
                host.reloadFS(files);
                host.runQueuedTimeoutCallbacks();
                verifyTrace(resolutionTrace, [
                    getExpectedReusingResolutionFromOldProgram(file1, module1Name),
                    getExpectedReusingResolutionFromOldProgram(file1, module2Name)
                ]);
                verifyWatchesWithConfigFile(host, files, file1);
            });

            it("non relative module name", () => {
                const module1Name = "module1";
                const module2Name = "module2";
                const fileContent = `import { module1 } from "${module1Name}";import { module2 } from "${module2Name}";`;
                const { file1, file2 } = getFiles(fileContent);
                const { module1, module2 } = getModules(`${projectLocation}/src/node_modules/module1/index.ts`, `${projectLocation}/node_modules/module2/index.ts`);
                const files = [module1, module2, file1, file2, configFile, libFile];
                const host = createServerHost(files);
                const resolutionTrace = createHostModuleResolutionTrace(host);
                const service = createProjectService(host);
                service.openClientFile(file1.path);
                const expectedTrace = getExpectedNonRelativeModuleResolutionTrace(host, file1, module1, module1Name);
                getExpectedNonRelativeModuleResolutionTrace(host, file1, module2, module2Name, expectedTrace);
                verifyTrace(resolutionTrace, expectedTrace);
                verifyWatchesWithConfigFile(host, files, file1);

                file1.content += fileContent;
                file2.content += fileContent;
                host.reloadFS(files);
                host.runQueuedTimeoutCallbacks();
                verifyTrace(resolutionTrace, [
                    getExpectedReusingResolutionFromOldProgram(file1, module1Name),
                    getExpectedReusingResolutionFromOldProgram(file1, module2Name)
                ]);
                verifyWatchesWithConfigFile(host, files, file1);
            });
        });

        describe("from files in different folders", () => {
            function getFiles(fileContent1: string, fileContent2 = fileContent1, fileContent3 = fileContent1, fileContent4 = fileContent1) {
                const file1: File = {
                    path: `${projectLocation}/product/src/file1.ts`,
                    content: fileContent1
                };
                const file2: File = {
                    path: `${projectLocation}/product/src/feature/file2.ts`,
                    content: fileContent2
                };
                const file3: File = {
                    path: `${projectLocation}/product/test/src/file3.ts`,
                    content: fileContent3
                };
                const file4: File = {
                    path: `${projectLocation}/product/test/file4.ts`,
                    content: fileContent4
                };
                return { file1, file2, file3, file4 };
            }

            it("relative module name", () => {
                const module1Name = "./module1";
                const module2Name = "../module2";
                const module3Name = "../module1";
                const module4Name = "../../module2";
                const module5Name = "../../src/module1";
                const module6Name = "../src/module1";
                const fileContent1 = `import { module1 } from "${module1Name}";import { module2 } from "${module2Name}";`;
                const fileContent2 = `import { module1 } from "${module3Name}";import { module2 } from "${module4Name}";`;
                const fileContent3 = `import { module1 } from "${module5Name}";import { module2 } from "${module4Name}";`;
                const fileContent4 = `import { module1 } from "${module6Name}";import { module2 } from "${module2Name}";`;
                const { file1, file2, file3, file4 } = getFiles(fileContent1, fileContent2, fileContent3, fileContent4);
                const { module1, module2 } = getModules(`${projectLocation}/product/src/module1.ts`, `${projectLocation}/product/module2.ts`);
                const files = [module1, module2, file1, file2, file3, file4, configFile, libFile];
                const host = createServerHost(files);
                const resolutionTrace = createHostModuleResolutionTrace(host);
                const service = createProjectService(host);
                service.openClientFile(file1.path);
                const expectedTrace = getExpectedRelativeModuleResolutionTrace(host, file1, module1, module1Name);
                getExpectedRelativeModuleResolutionTrace(host, file1, module2, module2Name, expectedTrace);
                getExpectedRelativeModuleResolutionTrace(host, file2, module1, module3Name, expectedTrace);
                getExpectedRelativeModuleResolutionTrace(host, file2, module2, module4Name, expectedTrace);
                getExpectedRelativeModuleResolutionTrace(host, file4, module1, module6Name, expectedTrace);
                getExpectedRelativeModuleResolutionTrace(host, file4, module2, module2Name, expectedTrace);
                getExpectedRelativeModuleResolutionTrace(host, file3, module1, module5Name, expectedTrace);
                getExpectedRelativeModuleResolutionTrace(host, file3, module2, module4Name, expectedTrace);
                verifyTrace(resolutionTrace, expectedTrace);
                verifyWatchesWithConfigFile(host, files, file1);

                file1.content += fileContent1;
                file2.content += fileContent2;
                file3.content += fileContent3;
                file4.content += fileContent4;
                host.reloadFS(files);
                host.runQueuedTimeoutCallbacks();

                verifyTrace(resolutionTrace, [
                    getExpectedReusingResolutionFromOldProgram(file1, module1Name),
                    getExpectedReusingResolutionFromOldProgram(file1, module2Name)
                ]);
                verifyWatchesWithConfigFile(host, files, file1);
            });

            it("non relative module name", () => {
                const module1Name = "module1";
                const module2Name = "module2";
                const fileContent = `import { module1 } from "${module1Name}";import { module2 } from "${module2Name}";`;
                const { file1, file2, file3, file4 } = getFiles(fileContent);
                const { module1, module2 } = getModules(`${projectLocation}/product/node_modules/module1/index.ts`, `${projectLocation}/node_modules/module2/index.ts`);
                const files = [module1, module2, file1, file2, file3, file4, configFile, libFile];
                const host = createServerHost(files);
                const resolutionTrace = createHostModuleResolutionTrace(host);
                const service = createProjectService(host);
                service.openClientFile(file1.path);
                const expectedTrace = getExpectedNonRelativeModuleResolutionTrace(host, file1, module1, module1Name);
                getExpectedNonRelativeModuleResolutionTrace(host, file1, module2, module2Name, expectedTrace);
                getExpectedNonRelativeModuleResolutionFromCacheTrace(host, file2, module1, module1Name, getDirectoryPath(file1.path), expectedTrace);
                getExpectedNonRelativeModuleResolutionFromCacheTrace(host, file2, module2, module2Name, getDirectoryPath(file1.path), expectedTrace);
                getExpectedNonRelativeModuleResolutionFromCacheTrace(host, file4, module1, module1Name, `${projectLocation}/product`, expectedTrace);
                getExpectedNonRelativeModuleResolutionFromCacheTrace(host, file4, module2, module2Name, `${projectLocation}/product`, expectedTrace);
                getExpectedNonRelativeModuleResolutionFromCacheTrace(host, file3, module1, module1Name, getDirectoryPath(file4.path), expectedTrace);
                getExpectedNonRelativeModuleResolutionFromCacheTrace(host, file3, module2, module2Name, getDirectoryPath(file4.path), expectedTrace);
                verifyTrace(resolutionTrace, expectedTrace);
                verifyWatchesWithConfigFile(host, files, file1);

                file1.content += fileContent;
                file2.content += fileContent;
                file3.content += fileContent;
                file4.content += fileContent;
                host.reloadFS(files);
                host.runQueuedTimeoutCallbacks();

                verifyTrace(resolutionTrace, [
                    getExpectedReusingResolutionFromOldProgram(file1, module1Name),
                    getExpectedReusingResolutionFromOldProgram(file1, module2Name)
                ]);
                verifyWatchesWithConfigFile(host, files, file1);
            });

            it("non relative module name from inferred project", () => {
                const module1Name = "module1";
                const module2Name = "module2";
                const file2Name = "./feature/file2";
                const file3Name = "../test/src/file3";
                const file4Name = "../test/file4";
                const importModuleContent = `import { module1 } from "${module1Name}";import { module2 } from "${module2Name}";`;
                const { file1, file2, file3, file4 } = getFiles(`import "${file2Name}"; import "${file4Name}"; import "${file3Name}"; ${importModuleContent}`, importModuleContent, importModuleContent, importModuleContent);
                const { module1, module2 } = getModules(`${projectLocation}/product/node_modules/module1/index.ts`, `${projectLocation}/node_modules/module2/index.ts`);
                const files = [module1, module2, file1, file2, file3, file4, libFile];
                const host = createServerHost(files);
                const resolutionTrace = createHostModuleResolutionTrace(host);
                const service = createProjectService(host);
                service.setCompilerOptionsForInferredProjects({ traceResolution: true });
                service.openClientFile(file1.path);
                const expectedTrace = getExpectedRelativeModuleResolutionTrace(host, file1, file2, file2Name);
                getExpectedRelativeModuleResolutionTrace(host, file1, file4, file4Name, expectedTrace);
                getExpectedRelativeModuleResolutionTrace(host, file1, file3, file3Name, expectedTrace);
                getExpectedNonRelativeModuleResolutionTrace(host, file1, module1, module1Name, expectedTrace);
                getExpectedNonRelativeModuleResolutionTrace(host, file1, module2, module2Name, expectedTrace);
                getExpectedNonRelativeModuleResolutionFromCacheTrace(host, file2, module1, module1Name, getDirectoryPath(file1.path), expectedTrace);
                getExpectedNonRelativeModuleResolutionFromCacheTrace(host, file2, module2, module2Name, getDirectoryPath(file1.path), expectedTrace);
                getExpectedNonRelativeModuleResolutionFromCacheTrace(host, file4, module1, module1Name, `${projectLocation}/product`, expectedTrace);
                getExpectedNonRelativeModuleResolutionFromCacheTrace(host, file4, module2, module2Name, `${projectLocation}/product`, expectedTrace);
                getExpectedNonRelativeModuleResolutionFromCacheTrace(host, file3, module1, module1Name, getDirectoryPath(file4.path), expectedTrace);
                getExpectedNonRelativeModuleResolutionFromCacheTrace(host, file3, module2, module2Name, getDirectoryPath(file4.path), expectedTrace);
                verifyTrace(resolutionTrace, expectedTrace);

                const currentDirectory = getDirectoryPath(file1.path);
                const watchedFiles = mapDefined(files, f => f === file1 ? undefined : f.path);
                forEachAncestorDirectory(currentDirectory, d => {
                    watchedFiles.push(combinePaths(d, "tsconfig.json"), combinePaths(d, "jsconfig.json"));
                });
                const watchedRecursiveDirectories = getTypeRootsFromLocation(currentDirectory).concat([
                    currentDirectory, `${projectLocation}/product/${nodeModules}`,
                    `${projectLocation}/${nodeModules}`, `${projectLocation}/product/test/${nodeModules}`,
                    `${projectLocation}/product/test/src/${nodeModules}`
                ]);
                checkWatches();

                file1.content += importModuleContent;
                file2.content += importModuleContent;
                file3.content += importModuleContent;
                file4.content += importModuleContent;
                host.reloadFS(files);
                host.runQueuedTimeoutCallbacks();

                verifyTrace(resolutionTrace, [
                    getExpectedReusingResolutionFromOldProgram(file1, file2Name),
                    getExpectedReusingResolutionFromOldProgram(file1, file4Name),
                    getExpectedReusingResolutionFromOldProgram(file1, file3Name),
                    getExpectedReusingResolutionFromOldProgram(file1, module1Name),
                    getExpectedReusingResolutionFromOldProgram(file1, module2Name)
                ]);
                checkWatches();

                function checkWatches() {
                    checkWatchedFiles(host, watchedFiles);
                    checkWatchedDirectories(host, [], /*recursive*/ false);
                    checkWatchedDirectories(host, watchedRecursiveDirectories, /*recursive*/ true);
                }
            });
        });

        describe("when watching directories for failed lookup locations in amd resolution", () => {
            const projectRoot = "/user/username/projects/project";
            const nodeFile: File = {
                path: `${projectRoot}/src/typings/node.d.ts`,
                content: `
declare module "fs" {
    export interface something {
    }
}`
            };
            const electronFile: File = {
                path: `${projectRoot}/src/typings/electron.d.ts`,
                content: `
declare module 'original-fs' {
    import * as fs from 'fs';
    export = fs;
}`
            };
            const srcFile: File = {
                path: `${projectRoot}/src/somefolder/srcfile.ts`,
                content: `
import { x } from "somefolder/module1";
import { x } from "somefolder/module2";
const y = x;`
            };
            const moduleFile: File = {
                path: `${projectRoot}/src/somefolder/module1.ts`,
                content: `
export const x = 10;`
            };
            const configFile: File = {
                path: `${projectRoot}/src/tsconfig.json`,
                content: JSON.stringify({
                    compilerOptions: {
                        module: "amd",
                        moduleResolution: "classic",
                        target: "es5",
                        outDir: "../out",
                        baseUrl: "./",
                        typeRoots: ["typings"]

                    }
                })
            };

            function verifyModuleResolution(useNodeFile: boolean) {
                const files = [...(useNodeFile ? [nodeFile] : []), electronFile, srcFile, moduleFile, configFile, libFile];
                const host = createServerHost(files);
                const service = createProjectService(host);
                service.openClientFile(srcFile.path, srcFile.content, ScriptKind.TS, projectRoot);
                checkProjectActualFiles(service.configuredProjects.get(configFile.path)!, files.map(f => f.path));
                checkWatchedFilesDetailed(host, mapDefined(files, f => f === srcFile ? undefined : f.path), 1);
                if (useNodeFile) {
                    checkWatchedDirectories(host, emptyArray,  /*recursive*/ false); // since fs resolves to ambient module, shouldnt watch failed lookup
                }
                else {
                    checkWatchedDirectoriesDetailed(host, [`${projectRoot}`], 1,  /*recursive*/ false); // failed lookup for fs
                }
                const expectedWatchedDirectories = createMap<number>();
                expectedWatchedDirectories.set(`${projectRoot}/src`, 2); // Wild card and failed lookup
                expectedWatchedDirectories.set(`${projectRoot}/somefolder`, 1); // failed lookup for somefolder/module2
                expectedWatchedDirectories.set(`${projectRoot}/node_modules`, 1); // failed lookup for with node_modules/@types/fs
                expectedWatchedDirectories.set(`${projectRoot}/src/typings`, 1); // typeroot directory
                checkWatchedDirectoriesDetailed(host, expectedWatchedDirectories, /*recursive*/ true);
            }

            it("when resolves to ambient module", () => {
                verifyModuleResolution(/*useNodeFile*/ true);
            });

            it("when resolution fails", () => {
                verifyModuleResolution(/*useNodeFile*/ false);
            });
        });
    });

    describe("tsserverProjectSystem watchDirectories implementation", () => {
        function verifyCompletionListWithNewFileInSubFolder(tscWatchDirectory: Tsc_WatchDirectory) {
            const projectFolder = "/a/username/project";
            const projectSrcFolder = `${projectFolder}/src`;
            const configFile: File = {
                path: `${projectFolder}/tsconfig.json`,
                content: "{}"
            };
            const index: File = {
                path: `${projectSrcFolder}/index.ts`,
                content: `import {} from "./"`
            };
            const file1: File = {
                path: `${projectSrcFolder}/file1.ts`,
                content: ""
            };

            const files = [index, file1, configFile, libFile];
            const fileNames = files.map(file => file.path);
            // All closed files(files other than index), project folder, project/src folder and project/node_modules/@types folder
            const expectedWatchedFiles = arrayToMap(fileNames.slice(1), s => s, () => 1);
            const expectedWatchedDirectories = createMap<number>();
            const mapOfDirectories = tscWatchDirectory === Tsc_WatchDirectory.NonRecursiveWatchDirectory ?
                expectedWatchedDirectories :
                tscWatchDirectory === Tsc_WatchDirectory.WatchFile ?
                    expectedWatchedFiles :
                    createMap();
            // For failed resolution lookup and tsconfig files
            mapOfDirectories.set(projectFolder, 2);
            // Through above recursive watches
            mapOfDirectories.set(projectSrcFolder, 2);
            // node_modules/@types folder
            mapOfDirectories.set(`${projectFolder}/${nodeModulesAtTypes}`, 1);
            const expectedCompletions = ["file1"];
            const completionPosition = index.content.lastIndexOf('"');
            const environmentVariables = createMap<string>();
            environmentVariables.set("TSC_WATCHDIRECTORY", tscWatchDirectory);
            const host = createServerHost(files, { environmentVariables });
            const projectService = createProjectService(host);
            projectService.openClientFile(index.path);

            const project = Debug.assertDefined(projectService.configuredProjects.get(configFile.path));
            verifyProjectAndCompletions();

            // Add file2
            const file2: File = {
                path: `${projectSrcFolder}/file2.ts`,
                content: ""
            };
            files.push(file2);
            fileNames.push(file2.path);
            expectedWatchedFiles.set(file2.path, 1);
            expectedCompletions.push("file2");
            host.reloadFS(files);
            host.runQueuedTimeoutCallbacks();
            assert.equal(projectService.configuredProjects.get(configFile.path), project);
            verifyProjectAndCompletions();

            function verifyProjectAndCompletions() {
                const completions = project.getLanguageService().getCompletionsAtPosition(index.path, completionPosition, { includeExternalModuleExports: false, includeInsertTextCompletions: false })!;
                checkArray("Completion Entries", completions.entries.map(e => e.name), expectedCompletions);

                checkWatchedDirectories(host, emptyArray, /*recursive*/ true);

                checkWatchedFilesDetailed(host, expectedWatchedFiles);
                checkWatchedDirectoriesDetailed(host, expectedWatchedDirectories, /*recursive*/ false);
                checkProjectActualFiles(project, fileNames);
            }
        }

        it("uses watchFile when file is added to subfolder, completion list has new file", () => {
            verifyCompletionListWithNewFileInSubFolder(Tsc_WatchDirectory.WatchFile);
        });

        it("uses non recursive watchDirectory when file is added to subfolder, completion list has new file", () => {
            verifyCompletionListWithNewFileInSubFolder(Tsc_WatchDirectory.NonRecursiveWatchDirectory);
        });

        it("uses dynamic polling when file is added to subfolder, completion list has new file", () => {
            verifyCompletionListWithNewFileInSubFolder(Tsc_WatchDirectory.DynamicPolling);
        });
    });

    describe("tsserverProjectSystem getEditsForFileRename", () => {
        it("works for host implementing 'resolveModuleNames' and 'getResolvedModuleWithFailedLookupLocationsFromCache'", () => {
            const userTs: File = {
                path: "/user.ts",
                content: 'import { x } from "./old";',
            };
            const newTs: File = {
                path: "/new.ts",
                content: "export const x = 0;",
            };
            const tsconfig: File = {
                path: "/tsconfig.json",
                content: "{}",
            };

            const host = createServerHost([userTs, newTs, tsconfig]);
            const projectService = createProjectService(host);
            projectService.openClientFile(userTs.path);
            const project = projectService.configuredProjects.get(tsconfig.path)!;

            Debug.assert(!!project.resolveModuleNames);

            const edits = project.getLanguageService().getEditsForFileRename("/old.ts", "/new.ts", testFormatOptions, emptyOptions);
            assert.deepEqual<ReadonlyArray<FileTextChanges>>(edits, [{
                fileName: "/user.ts",
                textChanges: [{
                    span: textSpanFromSubstring(userTs.content, "./old"),
                    newText: "./new",
                }],
            }]);
        });

        it("works with multiple projects", () => {
            const aUserTs: File = {
                path: "/a/user.ts",
                content: 'import { x } from "./old";',
            };
            const aOldTs: File = {
                path: "/a/old.ts",
                content: "export const x = 0;",
            };
            const aTsconfig: File = {
                path: "/a/tsconfig.json",
                content: "{}",
            };
            const bUserTs: File = {
                path: "/b/user.ts",
                content: 'import { x } from "../a/old";',
            };
            const bTsconfig: File = {
                path: "/b/tsconfig.json",
                content: "{}",
            };

            const host = createServerHost([aUserTs, aOldTs, aTsconfig, bUserTs, bTsconfig]);
            const session = createSession(host);
            openFilesForSession([aUserTs, bUserTs], session);

            const renameRequest = makeSessionRequest<protocol.GetEditsForFileRenameRequestArgs>(CommandNames.GetEditsForFileRename, {
                oldFilePath: "/a/old.ts",
                newFilePath: "/a/new.ts",
            });
            const response = session.executeCommand(renameRequest).response as protocol.GetEditsForFileRenameResponse["body"];
            assert.deepEqual(response, [
                {
                    fileName: aUserTs.path,
                    textChanges: [{ ...protocolTextSpanFromSubstring(aUserTs.content, "./old"), newText: "./new" }],
                },
                {
                    fileName: bUserTs.path,
                    textChanges: [{ ...protocolTextSpanFromSubstring(bUserTs.content, "../a/old"), newText: "../a/new" }],
                },
            ]);
        });
    });

    describe("tsserverProjectSystem document registry in project service", () => {
        const projectRootPath = "/user/username/projects/project";
        const importModuleContent = `import {a} from "./module1"`;
        const file: File = {
            path: `${projectRootPath}/index.ts`,
            content: importModuleContent
        };
        const moduleFile: File = {
            path: `${projectRootPath}/module1.d.ts`,
            content: "export const a: number;"
        };
        const configFile: File = {
            path: `${projectRootPath}/tsconfig.json`,
            content: JSON.stringify({ files: ["index.ts"] })
        };

        function getProject(service: TestProjectService) {
            return service.configuredProjects.get(configFile.path)!;
        }

        function checkProject(service: TestProjectService, moduleIsOrphan: boolean) {
            // Update the project
            const project = getProject(service);
            project.getLanguageService();
            checkProjectActualFiles(project, [file.path, libFile.path, configFile.path, ...(moduleIsOrphan ? [] : [moduleFile.path])]);
            const moduleInfo = service.getScriptInfo(moduleFile.path)!;
            assert.isDefined(moduleInfo);
            assert.equal(moduleInfo.isOrphan(), moduleIsOrphan);
            const key = service.documentRegistry.getKeyForCompilationSettings(project.getCompilationSettings());
            assert.deepEqual(service.documentRegistry.getLanguageServiceRefCounts(moduleInfo.path), [[key, moduleIsOrphan ? undefined : 1]]);
        }

        function createServiceAndHost() {
            const host = createServerHost([file, moduleFile, libFile, configFile]);
            const service = createProjectService(host);
            service.openClientFile(file.path);
            checkProject(service, /*moduleIsOrphan*/ false);
            return { host, service };
        }

        function changeFileToNotImportModule(service: TestProjectService) {
            const info = service.getScriptInfo(file.path)!;
            service.applyChangesToFile(info, [{ span: { start: 0, length: importModuleContent.length }, newText: "" }]);
            checkProject(service, /*moduleIsOrphan*/ true);
        }

        function changeFileToImportModule(service: TestProjectService) {
            const info = service.getScriptInfo(file.path)!;
            service.applyChangesToFile(info, [{ span: { start: 0, length: 0 }, newText: importModuleContent }]);
            checkProject(service, /*moduleIsOrphan*/ false);
        }

        it("Caches the source file if script info is orphan", () => {
            const { service } = createServiceAndHost();
            const project = getProject(service);

            const moduleInfo = service.getScriptInfo(moduleFile.path)!;
            const sourceFile = moduleInfo.cacheSourceFile.sourceFile;
            assert.equal(project.getSourceFile(moduleInfo.path), sourceFile);

            // edit file
            changeFileToNotImportModule(service);
            assert.equal(moduleInfo.cacheSourceFile.sourceFile, sourceFile);

            // write content back
            changeFileToImportModule(service);
            assert.equal(moduleInfo.cacheSourceFile.sourceFile, sourceFile);
            assert.equal(project.getSourceFile(moduleInfo.path), sourceFile);
        });

        it("Caches the source file if script info is orphan, and orphan script info changes", () => {
            const { host, service } = createServiceAndHost();
            const project = getProject(service);

            const moduleInfo = service.getScriptInfo(moduleFile.path)!;
            const sourceFile = moduleInfo.cacheSourceFile.sourceFile;
            assert.equal(project.getSourceFile(moduleInfo.path), sourceFile);

            // edit file
            changeFileToNotImportModule(service);
            assert.equal(moduleInfo.cacheSourceFile.sourceFile, sourceFile);

            const updatedModuleContent = moduleFile.content + "\nexport const b: number;";
            host.writeFile(moduleFile.path, updatedModuleContent);

            // write content back
            changeFileToImportModule(service);
            assert.notEqual(moduleInfo.cacheSourceFile.sourceFile, sourceFile);
            assert.equal(project.getSourceFile(moduleInfo.path), moduleInfo.cacheSourceFile.sourceFile);
            assert.equal(moduleInfo.cacheSourceFile.sourceFile.text, updatedModuleContent);
        });
    });

    describe("tsserverProjectSystem syntax operations", () => {
        function navBarFull(session: TestSession, file: File) {
            return JSON.stringify(session.executeCommandSeq<protocol.FileRequest>({
                command: protocol.CommandTypes.NavBarFull,
                arguments: { file: file.path }
            }).response);
        }

        function openFile(session: TestSession, file: File) {
            session.executeCommandSeq<protocol.OpenRequest>({
                command: protocol.CommandTypes.Open,
                arguments: { file: file.path, fileContent: file.content }
            });
        }

        it("works when file is removed and added with different content", () => {
            const projectRoot = "/user/username/projects/myproject";
            const app: File = {
                path: `${projectRoot}/app.ts`,
                content: "console.log('Hello world');"
            };
            const unitTest1: File = {
                path: `${projectRoot}/unitTest1.ts`,
                content: `import assert = require('assert');

describe("Test Suite 1", () => {
    it("Test A", () => {
        assert.ok(true, "This shouldn't fail");
    });

    it("Test B", () => {
        assert.ok(1 === 1, "This shouldn't fail");
        assert.ok(false, "This should fail");
    });
});`
            };
            const tsconfig: File = {
                path: `${projectRoot}/tsconfig.json`,
                content: "{}"
            };
            const files = [app, libFile, tsconfig];
            const host = createServerHost(files);
            const session = createSession(host);
            const service = session.getProjectService();
            openFile(session, app);

            checkNumberOfProjects(service, { configuredProjects: 1 });
            const project = service.configuredProjects.get(tsconfig.path)!;
            const expectedFilesWithoutUnitTest1 = files.map(f => f.path);
            checkProjectActualFiles(project, expectedFilesWithoutUnitTest1);

            host.writeFile(unitTest1.path, unitTest1.content);
            host.runQueuedTimeoutCallbacks();
            const expectedFilesWithUnitTest1 = expectedFilesWithoutUnitTest1.concat(unitTest1.path);
            checkProjectActualFiles(project, expectedFilesWithUnitTest1);

            openFile(session, unitTest1);
            checkProjectActualFiles(project, expectedFilesWithUnitTest1);

            const navBarResultUnitTest1 = navBarFull(session, unitTest1);
            host.removeFile(unitTest1.path);
            host.checkTimeoutQueueLengthAndRun(2);
            checkProjectActualFiles(project, expectedFilesWithoutUnitTest1);

            session.executeCommandSeq<protocol.CloseRequest>({
                command: protocol.CommandTypes.Close,
                arguments: { file: unitTest1.path }
            });
            checkProjectActualFiles(project, expectedFilesWithoutUnitTest1);

            const unitTest1WithChangedContent: File = {
                path: unitTest1.path,
                content: `import assert = require('assert');

export function Test1() {
    assert.ok(true, "This shouldn't fail");
};

export function Test2() {
    assert.ok(1 === 1, "This shouldn't fail");
    assert.ok(false, "This should fail");
};`
            };
            host.writeFile(unitTest1.path, unitTest1WithChangedContent.content);
            host.runQueuedTimeoutCallbacks();
            checkProjectActualFiles(project, expectedFilesWithUnitTest1);

            openFile(session, unitTest1WithChangedContent);
            checkProjectActualFiles(project, expectedFilesWithUnitTest1);
            const sourceFile = project.getLanguageService().getNonBoundSourceFile(unitTest1WithChangedContent.path);
            assert.strictEqual(sourceFile.text, unitTest1WithChangedContent.content);

            const navBarResultUnitTest1WithChangedContent = navBarFull(session, unitTest1WithChangedContent);
            assert.notStrictEqual(navBarResultUnitTest1WithChangedContent, navBarResultUnitTest1, "With changes in contents of unitTest file, we should see changed naviagation bar item result");
        });
    });

    function makeSampleProjects() {
        const aTs: File = {
            path: "/a/a.ts",
            content: "export function fnA() {}\nexport interface IfaceA {}\nexport const instanceA: IfaceA = {};",
        };
        const compilerOptions: CompilerOptions = {
            outDir: "bin",
            declaration: true,
            declarationMap: true,
            composite: true,
        };
        const configContent = JSON.stringify({ compilerOptions });
        const aTsconfig: File = { path: "/a/tsconfig.json", content: configContent };

        const aDtsMapContent: SourceMapSection = {
            version: 3,
            file: "a.d.ts",
            sourceRoot: "",
            sources: ["../a.ts"],
            names: [],
            mappings: "AAAA,wBAAgB,GAAG,SAAK;AACxB,MAAM,WAAW,MAAM;CAAG;AAC1B,eAAO,MAAM,SAAS,EAAE,MAAW,CAAC"
        };
        const aDtsMap: File = {
            path: "/a/bin/a.d.ts.map",
            content: JSON.stringify(aDtsMapContent),
        };
        const aDts: File = {
            path: "/a/bin/a.d.ts",
            // Need to mangle the sourceMappingURL part or it breaks the build
            content: `export declare function fnA(): void;\nexport interface IfaceA {\n}\nexport declare const instanceA: IfaceA;\n//# source${""}MappingURL=a.d.ts.map`,
        };

        const bTs: File = {
            path: "/b/b.ts",
            content: "export function fnB() {}",
        };
        const bTsconfig: File = { path: "/b/tsconfig.json", content: configContent };

        const bDtsMapContent: SourceMapSection = {
            version: 3,
            file: "b.d.ts",
            sourceRoot: "",
            sources: ["../b.ts"],
            names: [],
            mappings: "AAAA,wBAAgB,GAAG,SAAK",
        };
        const bDtsMap: File = {
            path: "/b/bin/b.d.ts.map",
            content: JSON.stringify(bDtsMapContent),
        };
        const bDts: File = {
            // Need to mangle the sourceMappingURL part or it breaks the build
            path: "/b/bin/b.d.ts",
            content: `export declare function fnB(): void;\n//# source${""}MappingURL=b.d.ts.map`,
        };

        const userTs: File = {
            path: "/user/user.ts",
            content: 'import { fnA, instanceA } from "../a/bin/a";\nimport { fnB } from "../b/bin/b";\nexport function fnUser() { fnA(); fnB(); instanceA; }',
        };

        const host = createServerHost([aTs, aTsconfig, aDtsMap, aDts, bTsconfig, bTs, bDtsMap, bDts, userTs]);
        const session = createSession(host);

        checkDeclarationFiles(aTs, session, [aDtsMap, aDts]);
        checkDeclarationFiles(bTs, session, [bDtsMap, bDts]);

        // Testing what happens if we delete the original sources.
        host.removeFile(bTs.path);

        openFilesForSession([userTs], session);

        return { session, aTs, bDts, userTs };
    }

    describe("tsserverProjectSystem project references", () => {
        it("goToDefinition", () => {
            const { session, aTs, userTs } = makeSampleProjects();
            const response = executeSessionRequest<protocol.DefinitionRequest, protocol.DefinitionResponse>(session, protocol.CommandTypes.Definition, protocolFileLocationFromSubstring(userTs, "fnA()"));
            assert.deepEqual(response, [protocolFileSpanFromSubstring(aTs, "fnA")]);
        });

        it("getDefinitionAndBoundSpan", () => {
            const { session, aTs, userTs } = makeSampleProjects();
            const response = executeSessionRequest<protocol.DefinitionAndBoundSpanRequest, protocol.DefinitionAndBoundSpanResponse>(session, protocol.CommandTypes.DefinitionAndBoundSpan, protocolFileLocationFromSubstring(userTs, "fnA()"));
            assert.deepEqual(response, {
                textSpan: protocolTextSpanFromSubstring(userTs.content, "fnA", { index: 1 }),
                definitions: [protocolFileSpanFromSubstring(aTs, "fnA")],
            });
        });

        it("goToType", () => {
            const { session, aTs, userTs } = makeSampleProjects();
            const response = executeSessionRequest<protocol.TypeDefinitionRequest, protocol.TypeDefinitionResponse>(session, protocol.CommandTypes.TypeDefinition, protocolFileLocationFromSubstring(userTs, "instanceA"));
            assert.deepEqual(response, [protocolFileSpanFromSubstring(aTs, "IfaceA")]);
        });

        it("goToImplementation", () => {
            const { session, aTs, userTs } = makeSampleProjects();
            const response = executeSessionRequest<protocol.ImplementationRequest, protocol.ImplementationResponse>(session, protocol.CommandTypes.Implementation, protocolFileLocationFromSubstring(userTs, "fnA()"));
            assert.deepEqual(response, [protocolFileSpanFromSubstring(aTs, "fnA")]);
        });

        it("goToDefinition -- target does not exist", () => {
            const { session, bDts, userTs } = makeSampleProjects();
            const response = executeSessionRequest<protocol.DefinitionRequest, protocol.DefinitionResponse>(session, CommandNames.Definition, protocolFileLocationFromSubstring(userTs, "fnB()"));
            // bTs does not exist, so stick with bDts
            assert.deepEqual(response, [protocolFileSpanFromSubstring(bDts, "fnB")]);
        });

        it("navigateTo", () => {
            const { session, aTs, bDts, userTs } = makeSampleProjects();
            const response = executeSessionRequest<protocol.NavtoRequest, protocol.NavtoResponse>(session, CommandNames.Navto, { file: userTs.path, searchValue: "fn" });
            assert.deepEqual<ReadonlyArray<protocol.NavtoItem> | undefined>(response, [
                {
                    ...protocolFileSpanFromSubstring(bDts, "export declare function fnB(): void;"),
                    name: "fnB",
                    matchKind: "prefix",
                    isCaseSensitive: true,
                    kind: ScriptElementKind.functionElement,
                    kindModifiers: "export,declare",
                },
                {
                    ...protocolFileSpanFromSubstring(userTs, "export function fnUser() { fnA(); fnB(); instanceA; }"),
                    name: "fnUser",
                    matchKind: "prefix",
                    isCaseSensitive: true,
                    kind: ScriptElementKind.functionElement,
                    kindModifiers: "export",
                },
                {
                    ...protocolFileSpanFromSubstring(aTs, "export function fnA() {}"),
                    name: "fnA",
                    matchKind: "prefix",
                    isCaseSensitive: true,
                    kind: ScriptElementKind.functionElement,
                    kindModifiers: "export",
                },
            ]);
        });

        it("findAllReferences", () => {
            const { session, aTs, userTs } = makeSampleProjects();

            const response = executeSessionRequest<protocol.ReferencesRequest, protocol.ReferencesResponse>(session, protocol.CommandTypes.References, protocolFileLocationFromSubstring(userTs, "fnA()"));
            assert.deepEqual<protocol.ReferencesResponseBody | undefined>(response, {
                refs: [
                    makeReferenceItem(userTs, /*isDefinition*/ true, "fnA", "import { fnA, instanceA } from \"../a/bin/a\";"),
                    makeReferenceItem(userTs, /*isDefinition*/ false, "fnA", "export function fnUser() { fnA(); fnB(); instanceA; }", { index: 1 }),
                    makeReferenceItem(aTs, /*isDefinition*/ true, "fnA", "export function fnA() {}"),
                ],
                symbolName: "fnA",
                symbolStartOffset: protocolLocationFromSubstring(userTs.content, "fnA()").offset,
                symbolDisplayString: "(alias) fnA(): void\nimport fnA",
            });
        });

        it("findAllReferencesFull", () => {
            const { session, aTs, userTs } = makeSampleProjects();

            interface ReferencesFullRequest extends protocol.FileLocationRequest { command: protocol.CommandTypes.ReferencesFull; }
            interface ReferencesFullResponse extends protocol.Response { body: ReadonlyArray<ReferencedSymbol>; }
            const responseFull = executeSessionRequest<ReferencesFullRequest, ReferencesFullResponse>(session, protocol.CommandTypes.ReferencesFull, protocolFileLocationFromSubstring(userTs, "fnA()"));

            function fnAVoid(kind: SymbolDisplayPartKind): SymbolDisplayPart[] {
                return [
                    keywordPart(SyntaxKind.FunctionKeyword),
                    spacePart(),
                    displayPart("fnA", kind),
                    punctuationPart(SyntaxKind.OpenParenToken),
                    punctuationPart(SyntaxKind.CloseParenToken),
                    punctuationPart(SyntaxKind.ColonToken),
                    spacePart(),
                    keywordPart(SyntaxKind.VoidKeyword),
                ];
            }
            assert.deepEqual<ReadonlyArray<ReferencedSymbol>>(responseFull, [
                {
                    definition: {
                        ...documentSpanFromSubstring(userTs, "fnA"),
                        kind: ScriptElementKind.alias,
                        name: "(alias) function fnA(): void\nimport fnA",
                        containerKind: ScriptElementKind.unknown,
                        containerName: "",
                        displayParts: [
                            punctuationPart(SyntaxKind.OpenParenToken),
                            textPart("alias"),
                            punctuationPart(SyntaxKind.CloseParenToken),
                            spacePart(),
                            ...fnAVoid(SymbolDisplayPartKind.aliasName),
                            lineBreakPart(),
                            keywordPart(SyntaxKind.ImportKeyword),
                            spacePart(),
                            displayPart("fnA", SymbolDisplayPartKind.aliasName),
                        ],
                    },
                    references: [
                        makeReferenceEntry(userTs, /*isDefinition*/ true, "fnA"),
                        makeReferenceEntry(userTs, /*isDefinition*/ false, "fnA", { index: 1 }),
                    ],
                },
                {
                    definition: {
                        ...documentSpanFromSubstring(aTs, "fnA"),
                        kind: ScriptElementKind.functionElement,
                        name: "function fnA(): void",
                        containerKind: ScriptElementKind.unknown,
                        containerName: "",
                        displayParts: fnAVoid(SymbolDisplayPartKind.functionName),
                    },
                    references: [
                        makeReferenceEntry(aTs, /*isDefinition*/ true, "fnA"),
                    ],
                }
            ]);
        });

        it("findAllReferences -- target does not exist", () => {
            const { session, bDts, userTs } = makeSampleProjects();

            const response = executeSessionRequest<protocol.ReferencesRequest, protocol.ReferencesResponse>(session, protocol.CommandTypes.References, protocolFileLocationFromSubstring(userTs, "fnB()"));
            assert.deepEqual<protocol.ReferencesResponseBody | undefined>(response, {
                refs: [
                    makeReferenceItem(userTs, /*isDefinition*/ true, "fnB", "import { fnB } from \"../b/bin/b\";"),
                    makeReferenceItem(userTs, /*isDefinition*/ false, "fnB", "export function fnUser() { fnA(); fnB(); instanceA; }", { index: 1 }),
                    makeReferenceItem(bDts, /*isDefinition*/ true, "fnB", "export declare function fnB(): void;"),
                ],
                symbolName: "fnB",
                symbolStartOffset: protocolLocationFromSubstring(userTs.content, "fnB()").offset,
                symbolDisplayString: "(alias) fnB(): void\nimport fnB",
            });
        });

        it("renameLocations", () => {
            const { session, aTs, userTs } = makeSampleProjects();
            const response = executeSessionRequest<protocol.RenameRequest, protocol.RenameResponse>(session, protocol.CommandTypes.Rename, protocolFileLocationFromSubstring(userTs, "fnA()"));
            assert.deepEqual<protocol.RenameResponseBody | undefined>(response, {
                info: {
                    canRename: true,
                    displayName: "fnA",
                    fullDisplayName: "fnA",
                    kind: ScriptElementKind.alias,
                    kindModifiers: ScriptElementKindModifier.none,
                    localizedErrorMessage: undefined,
                },
                locs: [
                    {
                        file: userTs.path,
                        locs: [
                            protocolTextSpanFromSubstring(userTs.content, "fnA"),
                            protocolTextSpanFromSubstring(userTs.content, "fnA", { index: 1 }),
                        ],
                    },
                    {
                        file: aTs.path,
                        locs: [protocolTextSpanFromSubstring(aTs.content, "fnA")],
                    }
                ],
            });
        });

        it("renameLocationsFull", () => {
            const { session, aTs, userTs } = makeSampleProjects();
            const response = executeSessionRequest<protocol.RenameFullRequest, protocol.RenameFullResponse>(session, protocol.CommandTypes.RenameLocationsFull, protocolFileLocationFromSubstring(userTs, "fnA()"));
            assert.deepEqual<ReadonlyArray<RenameLocation>>(response, [
                documentSpanFromSubstring(userTs, "fnA"),
                documentSpanFromSubstring(userTs, "fnA", { index: 1 }),
                documentSpanFromSubstring(aTs, "fnA"),
            ]);
        });

        it("renameLocations -- target does not exist", () => {
            const { session, bDts, userTs } = makeSampleProjects();
            const response = executeSessionRequest<protocol.RenameRequest, protocol.RenameResponse>(session, protocol.CommandTypes.Rename, protocolFileLocationFromSubstring(userTs, "fnB()"));
            assert.deepEqual<protocol.RenameResponseBody | undefined>(response, {
                info: {
                    canRename: true,
                    displayName: "fnB",
                    fullDisplayName: "fnB",
                    kind: ScriptElementKind.alias,
                    kindModifiers: ScriptElementKindModifier.none,
                    localizedErrorMessage: undefined,
                },
                locs: [
                    {
                        file: userTs.path,
                        locs: [
                            protocolTextSpanFromSubstring(userTs.content, "fnB"),
                            protocolTextSpanFromSubstring(userTs.content, "fnB", { index: 1 }),
                        ],
                    },
                    {
                        file: bDts.path,
                        locs: [protocolTextSpanFromSubstring(bDts.content, "fnB")],
                    }
                ],
            });

        });
    });

    function makeReferenceItem(file: File, isDefinition: boolean, text: string, lineText: string, options?: SpanFromSubstringOptions): protocol.ReferencesResponseItem {
        return {
            ...protocolFileSpanFromSubstring(file, text, options),
            isDefinition,
            isWriteAccess: isDefinition,
            lineText,
        };
    }

    function makeReferenceEntry(file: File, isDefinition: boolean, text: string, options?: SpanFromSubstringOptions): ReferenceEntry {
        return {
            ...documentSpanFromSubstring(file, text, options),
            isDefinition,
            isWriteAccess: isDefinition,
            isInString: undefined,
        };
    }

    function checkDeclarationFiles(file: File, session: TestSession, expectedFiles: ReadonlyArray<File>): void {
        openFilesForSession([file], session);
        const project = Debug.assertDefined(session.getProjectService().getDefaultProjectForFile(file.path as server.NormalizedPath, /*ensureProject*/ false));
        const program = project.getCurrentProgram();
        const output = getFileEmitOutput(program, Debug.assertDefined(program.getSourceFile(file.path)), /*emitOnlyDtsFiles*/ true);
        closeFilesForSession([file], session);

        Debug.assert(!output.emitSkipped);
        assert.deepEqual(output.outputFiles, expectedFiles.map((e): OutputFile => ({ name: e.path, text: e.content, writeByteOrderMark: false })));
    }
}