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

Question

我正在按照此示例为服务编写单元测试（从Spring应用程序后端接收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，我一直遇到这个错误

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

这可能是什么原因引起的？

- med.b

Answer 1

问题在于当你调用spy时，它返回的是一个Array，而Array没有pipe函数。你需要从你的spy中返回一个Observable，就像这样：

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

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

观察returnValue如何是Observable.of(expectedTarifs)。 Observable.of创建一个Observable，它会立即按顺序发出您指定的一些值，并随后发出完成通知。 请参阅文档

在最新版本的rxjs中，我们可以使用of运算符。

import { of } from 'rxjs';

//... omitting some code here for brevity 

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

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

希望对您有所帮助

- Castro Roy

Answer 2

我不得不这样做才能让我的工作正常:

import { from } from 'rxjs';

之后:

return from([expectedTarifs]);

- zappa