在测试httpclient调用时，无法读取未定义的属性“管道”

Question

我试图在离子应用程序代码中对我的代码进行单元测试，调用端点并将响应映射到对象，它还添加了一个点击，这样我就可以将this.faults作为我的dataservice中的一个observable返回。

fetchFaults(): Observable<Fault[]>
{
return this.http.get<{data: Fault[]}>('https://server/api/faults')
  .pipe(tap((data) => this.faults = data.data) // cache
      , map((data) => data.data)); // return just Fault[] from data.data to the subscriber
}

我正试图测试

  describe('fetchFaults', () => {
    it('makes expected calls', () => {
      const httpClientStub: HttpClient = TestBed.get(HttpClient);
      spyOn(httpClientStub, 'get');
      service.fetchFaults();
      expect(httpClientStub.get).toHaveBeenCalled();
    });
  });

但是我收到错误无法读取属性'pipe'的undefined我需要从httpstub返回任何内容吗？

Answer 1

以下是针对您的服务编写单元测试的正确方法。

import { TestBed, fakeAsync, tick, getTestBed } from '@angular/core/testing';
import { HttpClientTestingModule, HttpTestingController } from '@angular/common/http/testing';

import { FaultService, Fault } from './fault.service';

describe('Program Service Tests', () => {
    let injector: TestBed;
    let service: FaultService;
    let httpMock: HttpTestingController;

    beforeEach(() => {
        TestBed.configureTestingModule({
            imports: [HttpClientTestingModule],
            providers: [
                FaultService
            ]
        });

        injector = getTestBed();
        service = injector.get(FaultService);
        httpMock = injector.get(HttpTestingController);
    });

    afterEach(() => {
        httpMock.verify();
    });

    it('should get the faults', fakeAsync(() => {
        const results = {data: []};

        service.fetchFaults().subscribe(_ => expect(results.data).toBe(_));

        const req = httpMock.expectOne((request: HttpRequest<any>): boolean => {
            expect(request.url).toEqual('https://server/api/faults');
            expect(request.method).toBe('GET');
            return true;
        });
        req.flush(results);
        tick();
    }));
});

---

您收到该错误的原因是您需要告诉间谍调用原始实现。你可以通过链接.and.callThrough()来做到这一点。一个更好，更彻底的测试实现是我上面包含的代码。