Testing components
You may have noticed that every time we used the Angular CLI to scaffold a new Angular app or generate an Angular artifact, it would also create some test files for us.
Test files in the Angular CLI contain the word spec in their filename so that it is easier for the Karma runner to find and run them. Mainly, the filename of a test is the same as the Angular artifact that is testing followed by the suffix .spec.ts. For example, the test file for the main component of an Angular app, app.component.ts, would be app.component.spec.ts and would reside in the same path as the component file.
Important Note
We should think about an Angular artifact and its corresponding test as one thing. When we change the logic of the artifact, we need to modify the unit test as well. Placing unit test files together with their Angular artifacts makes it easier for us to remember and edit both of them. It also helps us when we need to do some refactoring to our code, such as...
