Simple Picture Viewer - Testing

Important notes

Please fork this project, otherwise your changes will not be saved.
When you have finished the task, send us the link of the forked project.

Your Task

Your task is to get an understanding of this app and write tests for it. What to test is completely up to you and what you think should be tested.

Hints

• The files containing tests need to be imported in src/tests.ts
• You can use src/app/imageService.spec.ts as a boilerplate for other tests
• To run the normal app, and not the testing environment, set TEST_MODE to false in the file src/main.ts and then save and reload.