When you run the test command, Angular will run through each of these generated test files and check whether they exist and initialize properly. These simple tests don't know enough about the functionality of your application to do much else, but they are helpful as a place to start writing your own tests. They also provide a small amount of coverage that all the individual parts of your application can properly initialize on its own. You should look at these automatically generated test stubs as a ready-made space for you to add your own tests for your application.