Setup mutation testing

Author: staabm

.github/workflows/static-analysis.yml

@@ -85,6 +85,11 @@ jobs:
       - name: "PHPStan"
         run: "make phpstan"
 
+      - uses: "actions/upload-artifact@v4"
+        with:
+          name: "result-cache-${{ matrix.php-version }}${{ matrix.operating-system-packages}}"
+          path: "tmp/resultCache.php"
+
   static-analysis-with-result-cache:
     name: "PHPStan with result cache"
 

.github/workflows/tests.yml

@@ -222,3 +222,65 @@ jobs:
 
       - name: "Tests"
         run: "make tests"
+
+  mutation-testing:
+    name: "Mutation Testing"
+    runs-on: "ubuntu-latest"
+    needs: ["tests", "tests-levels"]
+
+    strategy:
+      fail-fast: false
+      matrix:
+        php-version:
+          - "8.2"
+          - "8.3"
+          - "8.4"
+        operating-system: [ubuntu-latest]
+
+    steps:
+      - name: "Checkout"
+        uses: actions/checkout@v5
+
+      - name: "Install PHP"
+        uses: "shivammathur/setup-php@v2"
+        with:
+          coverage: "pcov"
+          php-version: "${{ matrix.php-version }}"
+          tools: pecl, infection:0.31.7
+          extensions: ds,mbstring
+          ini-file: development
+          ini-values: memory_limit=-1
+
+      - uses: "ramsey/composer-install@v3"
+
+      - name: "Check PHP configuration"
+        run: "vendor/bin/phpunit --check-php-configuration"
+
+      - name: "Checkout build-infection"
+        uses: actions/checkout@v5
+        with:
+          repository: "phpstan/build-infection"
+          path: "build-infection"
+          ref: "1.x"
+
+      - name: "Install build-infection dependencies"
+        working-directory: "build-infection"
+        run: "composer install --no-interaction --no-progress"
+
+      - uses: "actions/download-artifact@v4"
+        with:
+          name: "result-cache-${{ matrix.php-version }}${{ matrix.operating-system-packages}}"
+          path: "tmp/"
+
+      - name: "Run infection"
+        run: |
+          git fetch --depth=1 origin $GITHUB_BASE_REF
+          infection \
+            --git-diff-base=origin/$GITHUB_BASE_REF \
+            --git-diff-lines \
+            --ignore-msi-with-no-mutations \
+            --min-msi=100 \
+            --min-covered-msi=100 \
+            --log-verbosity=all \
+            --debug \
+            --logger-text=php://stdout

infection.json5

@@ -0,0 +1,18 @@
+{
+  "$schema": "vendor/infection/infection/resources/schema.json",
+  "timeout": 30,
+  "source": {
+    "directories": [
+      "src"
+    ]
+  },
+  "staticAnalysisTool": "phpstan",
+  "logs": {
+    "text": "tmp/infection.log"
+  },
+  "bootstrap": "build-infection/vendor/autoload.php",
+  "mutators": {
+    "@default": false,
+    "PHPStan\\Infection\\TrinaryLogicMutator": true
+  }
+}