TypeError: Cannot read property 'pipe' of undefined - Angular Unit test

Question

I'm trying to write a unit test and I'm getting this error.

TypeError: Cannot read property 'pipe' of undefined at Jasmine

const mockServiceObj = jasmine.createSpyObj < FormRegistrationService > (["registerForm", "pipe"]);
const getCurrentSystemPreference = jasmine.createSpyObj < CurrentSystemPreferencesService > ([
    "getCurrentSystemPreference",
    "pipe",
]);

function getServiceManagerLinks(): ServiceManagerSharedLinksComponent {
    return new ServiceManagerSharedLinksComponent(null, mockServiceObj, getCurrentSystemPreference);
}

Answer 1

Probably the correct (or at least close to correct) unit tests approach for your situation.

You have currentSystemPreferencesService const and provide it to providers. Now it's accessible in all tests cases. You also provide getPreferences field as callable method. And of(true) means you return on Observable which is needed for pipe() in real code since you immediately call .pipe(...) after calling getPreferences(SystemPreference.APITestValue)

describe('ServiceManagerSharedLinksComponent ', () => {
  let component: ServiceManagerSharedLinksComponent ;
  let fixture: ComponentFixture<ServiceManagerSharedLinksComponent>;

  const currentSystemPreferencesService: any = {
    getPreferences: () => of(true),
  };

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [ServiceManagerSharedLinksComponent],
      providers: [
        {
          provide: FormRegistrationService,
          useValue: {}, // <-- You will need a different const for registerForm() method
        },
        {
          provide: CurrentSystemPreferencesService,
          useValue: currentSystemPreferencesService,
        },
      ],
    }).compileComponents();

    fixture = TestBed.createComponent(ServiceManagerSharedLinksComponent);
    component = fixture.componentInstance;
    fixture.detectChanges();
  }));

  it('should set display owner info when showOwnerInfo is TRUE', () => {
    expect(component.isDisplayOwnerInfoSetOnSystemPreference).toEqual(true);
  });
});