Angular 如何在@ngrx/data中对EntityCollectionServiceBase进行单元测试？如何测试@ngrx/数据服务？

我想测试我的ngrx数据服务：

@Injectable({
  providedIn: 'root',
})
export class PostsService extends EntityCollectionServiceBase<Post>{
  constructor(serviceElemtsFactory: EntityCollectionServiceElementsFactory) {
    super('Post', serviceElemtsFactory);
  }
}

但我收到了错误：

TypeError:无法分解“serviceElementsFactory.create（…）”的属性“dispatcher”，因为它未定义

我怎样才能正确地修改我的测试

describe('PatientService', () => {
  let service: PostsService;

  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [
        HttpClientTestingModule,
        EffectsModule.forRoot([]),
        StoreModule.forRoot({}),
        EntityDataModule.forRoot(entityConfig)
      ],
      providers: [
        {
          provide: EntityCollectionServiceElementsFactory,
          useValue: MockService(EntityCollectionServiceElementsFactory),
        },
        PostsService,
      ],
    }).compileComponents();
    service = TestBed.inject(PostsService);
  });

  it('should be created', () => {
    expect(service).toBeTruthy();
  });

});