Call created spy before change detection

Question

I want to call created spy method before change detection is triggered. here is my mocked class.

const stubStudentService: Pick<StudentsCrudService, keyof StudentsCrudService> =
  {
    getAllStudents: jasmine
      .createSpy('getAllStudents')
      .and.returnValue(of(studentPayload)),
     ...other methods
  };

How do I call that getAllStudents before fixture.detectChanges()

 beforeEach(() => {
    fixture = TestBed.createComponent(StudentsListComponent);
    component = fixture.componentInstance;
    <-- want to call that spy here --->
    fixture.detectChanges();
  });

I wanted to do this because of this issue. but can't figure out how to change the solution according to my mocked service https://stackoverflow.com/questions/69989284/...

Answer 1

You need to use TestBed.inject here:

beforeEach(() => {
  TestBed.configureTestingModule({
    // ...
    providers: [
      {
        provide: StudentsCrudService,
        useValue: stubStudentService,
      },
    ],
  });
});

beforeEach(() => {
  fixture = TestBed.createComponent(StudentsListComponent);
  component = fixture.componentInstance;

  const studentsCrudService = TestBed.inject(StudentsCrudService);
  // spyOn(studentsCrudService, 'getAllStudents')...;

  fixture.detectChanges();
});