Fixing the tests and understanding TestBed

To better understand the use of TestBed, we’ll fix the rest of our project’s tests by adding dependencies to the test files. We’ll start with the app.component.spec.ts file and make the fixes as follows:

describe('AppComponent', () => {
  beforeEach(async () => {
    await TestBed.configureTestingModule({
     declarations: [AppComponent],
     imports: [RouterTestingModule],
   }).compileComponents();
  });
  it('should create the app', () => {
    const fixture = TestBed.createComponent(AppComponent);
    const app = fixture.componentInstance;
    expect(app).toBeTruthy();
  });
});

In this test, we cleaned up the test cases that had already been created by the Angular CLI when we started the project....