feat: add autocomplete support for locales (#248)

Author: ST-DDT

src/index.ts

@@ -12,6 +12,7 @@ import { Hacker } from './hacker';
 import { Helpers } from './helpers';
 import { Image } from './image';
 import { Internet } from './internet';
+import type { KnownLocale } from './locales';
 import allLocales from './locales';
 import { Lorem } from './lorem';
 import { Mersenne } from './mersenne';
@@ -25,6 +26,9 @@ import { Unique } from './unique';
 import { Vehicle } from './vehicle';
 import { Word } from './word';
 
+// https://github.com/microsoft/TypeScript/issues/29729#issuecomment-471566609
+type LiteralUnion<T extends U, U = string> = T | (U & { zz_IGNORE_ME?: never });
+
 export interface LocaleDefinition {
   title: string;
   separator?: string;
@@ -186,12 +190,13 @@ export interface LocaleDefinition {
   [group: string]: any;
 }
 
+export type UsableLocale = LiteralUnion<KnownLocale>;
+export type UsedLocales = Partial<Record<UsableLocale, LocaleDefinition>>;
+
 export interface FakerOptions {
-  locales?: {
-    [locale: string]: LocaleDefinition;
-  };
-  locale?: string;
-  localeFallback?: string;
+  locales?: UsedLocales;
+  locale?: UsableLocale;
+  localeFallback?: UsableLocale;
 }
 
 export interface DefinitionTypes {
@@ -216,11 +221,9 @@ export interface DefinitionTypes {
 }
 
 export class Faker {
-  locales: {
-    [locale: string]: LocaleDefinition;
-  };
-  locale: string;
-  localeFallback: string;
+  locales: UsedLocales;
+  locale: UsableLocale;
+  localeFallback: UsableLocale;
 
   // TODO @Shinigami92 2022-01-11: For now we loose types here
   // @ts-expect-error: will be lazy filled by constructor
@@ -432,7 +435,7 @@ export class Faker {
    *
    * @param locale
    */
-  setLocale(locale: string): void {
+  setLocale(locale: UsableLocale): void {
     this.locale = locale;
   }
 }

src/locales/index.ts

@@ -56,7 +56,67 @@ import zh_CN from './zh_CN';
 import zh_TW from './zh_TW';
 import zu_ZA from './zu_ZA';
 
-const locales: { [lang: string]: LocaleDefinition } = {
+export type KnownLocale =
+  | 'af_ZA'
+  | 'ar'
+  | 'az'
+  | 'cz'
+  | 'de'
+  | 'de_AT'
+  | 'de_CH'
+  | 'el'
+  | 'en'
+  | 'en_AU'
+  | 'en_AU_ocker'
+  | 'en_BORK'
+  | 'en_CA'
+  | 'en_GB'
+  | 'en_GH'
+  | 'en_IE'
+  | 'en_IND'
+  | 'en_NG'
+  | 'en_US'
+  | 'en_ZA'
+  | 'es'
+  | 'es_MX'
+  | 'fa'
+  | 'fi'
+  | 'fr'
+  | 'fr_BE'
+  | 'fr_CA'
+  | 'fr_CH'
+  | 'ge'
+  | 'he'
+  | 'hr'
+  | 'hy'
+  | 'id_ID'
+  | 'it'
+  | 'ja'
+  | 'ko'
+  | 'lv'
+  | 'mk'
+  | 'nb_NO'
+  | 'ne'
+  | 'nl'
+  | 'nl_BE'
+  | 'pl'
+  | 'pt_BR'
+  | 'pt_PT'
+  | 'ro'
+  | 'ru'
+  | 'sk'
+  | 'sv'
+  | 'tr'
+  | 'uk'
+  | 'ur'
+  | 'vi'
+  | 'zh_CN'
+  | 'zh_TW'
+  | 'zu_ZA';
+
+export type KnownLocales = Record<KnownLocale, LocaleDefinition>;
+
+const locales: KnownLocales = {
   af_ZA,
   ar,
   az,