Add comprehensive test suite and GitHub Actions CI (#2)

* Add comprehensive test suite and GitHub Actions CI

- Add 30+ test cases covering execution, errors, globals, functions,
  booleans, macros, multi-return, multiple instances, and error messages
- Add macro expansion tests with diagnostic validation
- Add GitHub Actions workflow (macOS 14, Xcode 15.4)
- CI runs on push to main and all PRs
- Clean up stale test files

* Fix demo: add missing try for throwing execute()

* Fix linker error: add LuaKitMacros dependency to LuaKitTests target

The macro test file imports LuaKitMacros directly to reference
LuaFunctionMacro.self, but the test target was missing the dependency,
causing undefined symbol errors at link time.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: William Laverty <william@laverty.dev>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 3 people

.github/workflows/ci.yml

@@ -0,0 +1,33 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build-and-test:
+    name: Build & Test
+    runs-on: macos-14
+    strategy:
+      matrix:
+        xcode: ['15.4']
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Select Xcode ${{ matrix.xcode }}
+        run: sudo xcode-select -s /Applications/Xcode_${{ matrix.xcode }}.app
+
+      - name: Install Lua
+        run: brew install lua
+
+      - name: Build
+        run: swift build -v
+
+      - name: Run Tests
+        run: swift test -v

Package.swift

@@ -26,6 +26,7 @@ let package = Package(
             name: "LuaKitTests",
             dependencies: [
                 "LuaKit",
+                "LuaKitMacros",
                 .product(name: "SwiftSyntaxMacrosTestSupport", package: "swift-syntax")
             ]),
         .macro(name: "LuaKitMacros",

Sources/LuaKitDemo/main.swift

@@ -29,6 +29,6 @@ do {
         """#
 
         // Execute Lua code using the Lua instance
-        lua.execute(source: source)
+        try lua.execute(source: source)
     }
 }

Tests/LuaDemoTests/LuaDemoTests.swift

@@ -0,0 +1,14 @@
+//
+//  LuaDemoTests.swift
+//  Placeholder for demo integration tests.
+//  Created by William Laverty on 14/12/2023.
+//
+
+import XCTest
+
+final class LuaDemoTests: XCTestCase {
+    func testDemoTargetBuilds() throws {
+        // Validates the demo target compiles successfully
+        XCTAssertTrue(true)
+    }
+}