Jasmine 服务的单元测试没有 return 数据

Question

伙计们！我是测试人员的新手并且遇到了这个问题。我正在尝试为我的服务编写单元测试，它从服务器获取数据。经典案例：

import {TestBed} from '@angular/core/testing';
import {ShiftsService} from "./shifts.service";
import {Shift} from "../shift/shift";

describe('ShiftService - testing HTTP request method getShifts()', () => {
  let httpTestingController: HttpTestingController;

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

  it('can test HttpClient.get', () => {
    let shifts = new Array<Shift>();
    let shiftsService;
    let calendarMonth = new Date().getMonth()+2;
    let calendarYear  = new Date().getFullYear();
    shiftsService = TestBed.inject(ShiftsService);
    httpTestingController = TestBed.inject(HttpTestingController);
    shiftsService.getShifts(calendarYear, calendarMonth).subscribe(response => {expect(response).toBe(response.length);
    console.log(response);
    });

    let apiRequest:string = '/api/shifts?year='.concat(calendarYear.toString()).concat('&month=').concat(calendarMonth.toString());
    const req = httpTestingController.expectOne(apiRequest);
    console.log(apiRequest);
    expect(req.request.method).toBe('GET');

    req.flush(shifts);
  });

  afterEach(() => httpTestingController.verify());
});

我在服务文件中的方法如下所示：

getShifts (year: number, month: number): Observable<Shift[]> {
    let params = new HttpParams();
    params = params.append('year', year.toString());
    params = params.append('month', month.toString());

    return this.http.get<Shift[]>(this.shiftsUrl, { params: params })
      .pipe(tap((shifts) => shifts),
        catchError((err) => this.handleError(err)))
  }

我收到错误：错误：预期 [ ] 为 0。 当我打印出 response 变量时，我得到了它是空的！但我确信这种方法可以正常工作！它在我的应用程序中运行良好！你能帮我解决这个问题吗？如何更正我的测试方法来测试服务？

Answer 1

在最后，您正在做 req.flush(shifts) 和 shifts = new Array<Shift>();，这实际上是 []。刷新是您希望 HTTP get 请求响应的内容，在本例中它是一个空数组。

在订阅中，您断言 response ([]) 等于 response.length 即 0.

试试这个：

it('can test HttpClient.get', (done) => { // add done callback to be able to call it in the subscribe
    let shifts = new Array<Shift>();
    let shiftsService;
    let calendarMonth = new Date().getMonth()+2;
    let calendarYear  = new Date().getFullYear();
    shiftsService = TestBed.inject(ShiftsService);
    httpTestingController = TestBed.inject(HttpTestingController);
    shiftsService.getShifts(calendarYear, calendarMonth).subscribe(response => {
       // we have to use toEqual because toBe does a deep assertion
       // but the array to compare to is in a different location in memory so 
       // toBe would fail
       expect(response).toEqual([]);
       console.log(response);
       // call done to tell the unit test you are done with this test
       done();
    });

    let apiRequest:string = '/api/shifts?year='.concat(calendarYear.toString()).concat('&month=').concat(calendarMonth.toString());
    const req = httpTestingController.expectOne(apiRequest);
    console.log(apiRequest);
    expect(req.request.method).toBe('GET');

    shifts.push(/* push a shift here */) // change the shifts array to what you want the server to respond with 
    req.flush(shifts);
  });

Jasmine 服务的单元测试没有 return 数据

Unit test for service with Jasmine does not return data

jasmine

karma-runner

angular9