错误：StaticInjectorError(DynamicTestModule)[CityService -> Http]: No provider for Http

Question

我有这项服务，可以从 ws 返回所有城市。

@Injectable()
export class CityService {
  constructor(private http: Http, private router: Router,
  private auth: AuthService) { }

  public getAllCity(): Observable<City[]> {
    let headers = new Headers();
    headers.append('x-access-token', this.auth.getCurrentUser().token);
    return this.http.get(Api.getUrl(Api.URLS.getAllCity), {
      headers: headers
    })
      .map((response: Response) => {
        let res = response.json();
        if (res.StatusCode === 1) {
          this.auth.logout();
        } else {
          return res.StatusDescription.map(city => {
            return new City(city);
          });
        }
      });
  }
}

现在，我尝试了这段代码来测试我的服务。在这篇文章中我想知道，如何测试这个服务CityService

describe('Service: City', () => {
    let component: CityService;
    let fixture: ComponentFixture<CityService>;

    beforeEach(() => {
        TestBed.configureTestingModule({
            declarations: [],
            providers: [CityService] 
        })
        fixture = TestBed.get(CityService);
        component = fixture.componentInstance;
    });
   it('#getAllCity should return real value', () => {
     expect(component.getAllCity()).toBe('real value');
  });
});

我尝试了这段代码，但显示错误：

错误：StaticInjectorError(DynamicTestModule)[CityService -> Http]：
StaticInjectorError（平台：核心）[CityService -> Http]： NullInjectorError: 没有 Http 提供者！

如何测试/如何在ng test 中显示我的城市？

这是我的第一次尝试，你能给我一些例子，或者像我的代码这样的教程吗？

Answer 1

CityService 依赖于 3 个服务，即Http、Router 和AuthService。您需要将它们注入到测试中。

describe('Service: City', () => {
    let service: CityService;

    beforeEach(() => {
        TestBed.configureTestingModule({
            declarations: [],
            providers: [CityService, AuthService],  // all all services upon which AuthService depends
            imports: [RouterTestingModule, HttpClientTestingModule], 
        });
    });

    beforeEach(() => {
        service = TestBed.get(CityService);
    });

    it('#getAllCity should return real value', () => {
        expect(service.getAllCity()).toBe('real value');
    });
});

https://angular.io/guide/testing - 这是 Angular 单元测试的必读内容。 https://angular.io/guide/testing#service-tests - 与测试服务相关的部分。 https://angular.io/guide/http#setup-1 - 与测试使用 Http 服务进行的调用有关。