testing switchMap in component in Angular

Question

I have a component method with this format:

action(): Observable<void> {
    return this.service.actiontaken(this.ids).pipe(
      switchMap(() => {
        return this.otherMethod(this.ids);
      }),
    );
  }

I am able to test the part upto this.service.actiontaken, but the test I wrote is not reaching the area within switchMap.

it('action(): should call the service method', () => {
    service.actiontaken.mockReturnValue(of());
        const otherActionSpy = jest.spyOn(component, 'otherAction').mockReturnValue(of());
    fixture.detectChanges();
    component.action();
    expect(service.actiontaken).toHaveBeenCalledTimes(1);
    expect(otherActionSpy).toHaveBeenCalledTimes(1); // this part fails, and in coverage the part under switchMap is also not covered

  });

Please help on how to proceed with this.

Answer 1

Found the solution to this: Since action returns an Observable, subscribing to it will reach within switchMap.

it('action(): should call the service method', () => {
    service.actiontaken.mockReturnValue(of());
        const otherActionSpy = jest.spyOn(component, 'otherAction').mockReturnValue(of());
    fixture.detectChanges();
    component.action().subscribe(() => {
      expect(otherActionSpy).toHaveBeenCalledTimes(1);
    });
    expect(service.actiontaken).toHaveBeenCalledTimes(1);
  });