Add test action

Author: SimplyDanny

.github/workflows/Package.swift

@@ -0,0 +1,24 @@
+// swift-tools-version:5.9
+
+import PackageDescription
+
+let package = Package(
+    name: "SwiftLintPluginsTest",
+    platforms: [
+        .macOS(.v12),
+    ],
+    products: [
+        .executable(name: "Runner", targets: ["Runner"]),
+    ],
+    dependencies: [
+        .package(name: nil, path: "../SwiftLintPlugins"),
+    ],
+    targets: [
+        .executableTarget(
+            name: "Runner",
+            plugins: [
+                .plugin(name: "SwiftLintBuildToolPlugin", package: "SwiftLintPlugins"),
+            ]
+        ),
+    ]
+)

.github/workflows/test.yml

@@ -0,0 +1,41 @@
+name: Tests
+
+on: ["pull_request", "push"]
+
+env:
+  XCODE_VERSION: '15.0'
+
+defaults:
+  run:
+    shell: bash
+
+jobs:
+  plugin:
+    name: Test Plugin
+    runs-on: macos-13
+    steps:
+      - name: Select Xcode
+        uses: maxim-lobanov/setup-xcode@v1
+        with:
+          xcode-version: ${{ env.XCODE_VERSION }}
+      - name: Checkout SwiftLintPlugins
+        uses: actions/checkout@v4
+        with:
+          path: SwiftLintPlugins
+      - name: Create project directory
+        run: mkdir SwiftLintPluginsTest
+      - name: Configure project
+        run: |
+          swift package init --type executable
+          cp ../SwiftLintPlugins/.github/workflows/Package.swift .
+          echo "let myVar : Int = 0" > Sources/main.swift
+        working-directory: ./SwiftLintPluginsTest
+      - name: Build project and check findings
+        run: swift build 2>&1 | grep -q "Colon Spacing Violation"
+        working-directory: ./SwiftLintPluginsTest
+      - name: Verify command plugin
+        run: |
+          swift package swiftlint --help
+          swift package swiftlint --version
+          swift package swiftlint 2>&1 | grep -q "Colon Spacing Violation"
+        working-directory: ./SwiftLintPluginsTest