add stryker for mutation testing

.github/workflows/main.yaml

@@ -47,6 +47,9 @@ jobs:
           name: coverage-reports
           path: coverage/
 
+      - name: Run mutation testing
+        run: npm run mutate
+
       - name: Upload build artifacts
         uses: actions/upload-artifact@v4
         with:

.gitignore

@@ -1,3 +1,5 @@
-node_modules/
-dist/
 /coverage/
+/dist/
+/node_modules/
+/reports/
+/.stryker-tmp

package.json

@@ -17,7 +17,8 @@
     "lint-fix": "eslint . --ext .js,.ts --fix",
     "test": "jest",
     "coverage": "npx jest --coverage",
-    "all": "npm run lint-fix && npm run format && npm run build && npm run coverage"
+    "mutate": "stryker run",
+    "all": "npm run lint-fix && npm run format && npm run build && npm run coverage && npm run mutate"
   },
   "repository": {
     "type": "git",
@@ -36,6 +37,8 @@
     "@rollup/plugin-json": "^6.1.0",
     "@rollup/plugin-node-resolve": "^16.0.0",
     "@rollup/plugin-typescript": "^12.1.2",
+    "@stryker-mutator/core": "^8.7.1",
+    "@stryker-mutator/jest-runner": "^8.7.1",
     "@types/jest": "^29.5.14",
     "@types/jsdom": "^21.1.7",
     "@types/node": "^22.13.9",

stryker.conf.json

@@ -0,0 +1,15 @@
+{
+  "reporters": ["html", "clear-text", "progress"],
+  "testRunner": "jest",
+  "coverageAnalysis": "perTest",
+  "mutate": ["src/**/*.ts?(x)", "!src/__tests__/**/*.test.ts"],
+  "jest": {
+    "projectType": "custom"
+  },
+  "ignoreStatic": true,
+  "thresholds": {
+    "high": 90,
+    "low": 75,
+    "break": 65
+  }
+}