Угловое модульное тестирование: как выполнить модульное тестирование подписки внутри ngOnInIt ()?

Question

Проверяемый компонент:

export class ComponentDetailsComponent implements OnInit {
     ngOnInit() {

            this.componentDetailsService.currentProperties.subscribe((data) => {
                this.loader.hideLoader();    
                 this.showPopup = data.showPopup;
         .....more code....
    }

Спецификация:

class ComponentDetailsServiceStub {
  defaultProperties ={       
    showToolbar: false,        
    showPopup: true, //show popup is set to true here       
    refresh: false,
  };

    propertiesSource = new BehaviorSubject(this.defaultProperties);
  currentProperties = this.propertiesSource.asObservable();

  setDefaultCancelClicked(){}
}


it('should set showPopup to correct value', () => {

    componentDetailsService.propertiesSource.next({         
      showToolbar: true,         
      showPopup: false, // show popup is set to false          
      refresh: false,

    }); 

    expect(subject.showPopup).toBe(true) ///this always passes

   });