a bit tests

package.json

@@ -7,7 +7,7 @@
         "doc": "docs"
     },
     "scripts": {
-        "test": "echo \"Error: no test specified\" && exit 1",
+        "test": "jest",
         "start": "ijl-cli server --port=8099 --with-open-browser",
         "build": "npm run clean && ijl-cli build --dev",
         "build:prod": "npm run clean && ijl-cli build",
@@ -24,6 +24,7 @@
         "@types/react": "^18.2.74",
         "@types/react-dom": "^18.2.24",
         "express": "^4.19.2",
+        "jest-environment-jsdom": "^29.7.0",
         "react": "^18.2.0",
         "react-dom": "^18.2.0",
         "react-router-dom": "^6.23.0",
@@ -31,9 +32,13 @@
     },
     "devDependencies": {
         "@eslint/js": "^9.3.0",
+        "@jest/globals": "^29.7.0",
+        "@types/jest": "^29.5.12",
         "eslint": "^8.57.0",
         "eslint-plugin-react": "^7.34.1",
         "globals": "^15.2.0",
+        "jest": "^29.7.0",
+        "ts-jest": "^29.1.2",
         "typescript-eslint": "^7.9.0"
     }
 }