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

问题描述

我正在按照此示例进行服务的单元测试(获取来自Spring应用程序后端的请求) https://angular.io/guide/testing#testing-http-services

I'm following this example to make a unit test for service (get request coming from spring app backend) https://angular.io/guide/testing#testing-http-services

服务类别:

@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，我一直遇到此错误

When running the tests, I keep having this error

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?

推荐答案

问题是，当您的spy被调用时，它返回一个Array，而Array没有一个pipe函数.您需要从spy返回Observable，例如

The problem is that when your spy is being called, it is returning an Array and Array does not have a pipe function. You need to return an Observable from your spy, something like this

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

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

查看returnValue是Observable.of(expectedTarifs)的方式. Observable.of创建一个Observable，该Observable会立即发出一个您指定为自变量的值，然后发出一个完整的通知. 请参阅文档

See how the returnValue is Observable.of(expectedTarifs). Observable.of creates an Observable that emits some values you specify as arguments, immediately one after the other, and then emits a complete notification. See the docs

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