constructor(private searchService: SearchService, private storageService: StorageService) { 
this.searchService.pagesOutput.subscribe(images => {
  this.images = images;
  this.pages = this.searchService.numberOfPages;
  
})
}
I have a service as a dependency injection. I would like to mock it for test. I know how to mock service and some methods
 searchServiceMock = jasmine.createSpyObj('SearchService', ['pagesOutput']);
 searchServiceMock.pagesOutput.and.returnValue(someValue)
But how can I reach nested functions?(searchServiceMock.pagesOutput.subscribe?)