let userServiceStub: Partial;
beforeEach(() => {
  // stub UserService for test purposes
  userServiceStub = {
    isLoggedIn: true,
    user: { name: 'Test User'}
  };
  TestBed.configureTestingModule({
     declarations: [ WelcomeComponent ],
     providers:    [ {provide: UserService, useValue: userServiceStub } ]
  });
  fixture = TestBed.createComponent(WelcomeComponent);
  comp    = fixture.componentInstance;
  // UserService from the root injector
  userService = TestBed.get(UserService);
  //  get the "welcome" element by CSS selector (e.g., by class name)
  el = fixture.nativeElement.querySelector('.welcome');
});