Add mutation testing configuration and steps to CI

Author: chapterjason

.github/workflows/ci.yml

@@ -85,4 +85,20 @@ jobs:
             -   run: vendor/bin/phpunit --coverage-clover=coverage.xml
             -   uses: codecov/codecov-action@v5
                 env:
-                    CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
+                    CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
+    mutation-tests:
+        name: Mutation Tests
+        needs:
+            - dependency-validation
+        runs-on: ubuntu-latest
+        timeout-minutes: 5
+        steps:
+            -   uses: actions/checkout@v4
+            -   uses: shivammathur/setup-php@v2
+                with:
+                    php-version: 8.4
+                    tools: infection
+            -   uses: ramsey/composer-install@v3
+            -   run: infection --min-msi=58 --min-covered-msi=69 --threads=4
+                env:
+                    STRYKER_DASHBOARD_API_KEY: ${{ secrets.STRYKER_DASHBOARD_API_KEY }}

infection.json

@@ -0,0 +1,18 @@
+{
+  "source": {
+    "directories": [
+      "src"
+    ]
+  },
+  "timeout": 10,
+  "logs": {
+    "text": "coverage/infections.log",
+    "html": "coverage/mutants.html",
+    "stryker": {
+      "badge": "master"
+    }
+  },
+  "mutators": {
+    "@default": true
+  }
+}