Angular单元测试TypeError:this.http.get(...).pipe不是函数

Question

我正在按照这个例子对服务进行单元测试(来自spring app后端的get请求)https://angular.io/guide/testing#testing-http-services

服务类:

@Injectable()
export class TarifService {

  constructor(private messageService: MessageService, private http: HttpClient) { }

  public getTarifs(): Observable<Tarif[]> {
    return this.http.get<Tarif[]>(tarifffsURL).pipe(
      tap(() => {}),
      catchError(this.handleError('getTarifs', []))
    );
  }
}

单元测试

describe('TarifService', () => {

  let tarifService: TarifService;
  let httpClientSpy: { get: jasmine.Spy };
  let expectedTarifs;

  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [ToastrModule.forRoot(), HttpClientModule, HttpClientTestingModule],
      providers: [TarifService, HttpClient, MessageService]
    });

    httpClientSpy = jasmine.createSpyObj('HttpClient', ['get']);
    tarifService = new TarifService(<any> MessageService,<any> httpClientSpy);

  });


  it('should be created', inject([TarifService], (service: TarifService) => {
    expect(service).toBeTruthy();
  }));


  it('should return expected tarif (HttpClient called once)', () => {
    const expectedTarifs: Tarif[] =
      [{ id: 1, name: 'Tarif1', value: '20' }, { id: 2, name: 'Tarif2', value:'30' }];

    httpClientSpy.get.and.returnValue(expectedTarifs);

    tarifService.getTarifs().subscribe(
      tarifs => expect(tarifs).toEqual(expectedTarifs, 'expected tarifs'),
      fail
    );
    expect(httpClientSpy.get.calls.count()).toBe(1, 'one call');
  });
});

运行测试时,我一直有这个错误

TarifService should return expected tarif (HttpClient called once)
TypeError: this.http.get(...).pipe is not a function

这可能是什么原因？

Answer 1

问题是当你spy被调用时,它返回一个Array并且Array没有pipe函数.你需要Observable从你spy这样的东西中 返回一个

const expectedTarifs: Tarif[] =
  [{ id: 1, name: 'Tarif1', value: '20' }, { id: 2, name: 'Tarif2', value:'30' }];

httpClientSpy.get.and.returnValue(Observable.of(expectedTarifs));

看怎么returnValue是Observable.of(expectedTarifs).Observable.of创建一个Observable发出一些您指定为参数的值,一个接一个地发出,然后发出完整的通知.查看文档

希望能帮助到你