feat: frontend unit tests

frontend/README.md

@@ -27,3 +27,39 @@ Open in browser: [http://localhost:8088](http://localhost:8088)
 Generates the folder "**_frontend/dist_**".
 
 Copy folders and files from "**_frontend/dist/static_**" into "**_static_**".
+
+---
+
+### Test Scripts
+
+#### test
+
+Run all unit tests once.
+
+```sh
+npm run test
+```
+
+#### test-watch
+
+Run tests in watch mode for development.
+
+```sh
+npm run test-watch
+```
+
+#### test-coverage
+
+Run tests with coverage reporting in `./coverage` folder.
+
+```sh
+npm run test-coverage
+```
+
+#### test-coverage-watch
+
+Run tests with coverage in watch mode.
+
+```sh
+npm run test-coverage-watch
+```