angular - Typescript - Angular 测试，如何使用 ngOnInit 中的参数处理 http 请求？

Question

我有一个模态组件，它从外部获取输入，打开后，确实会向服务器发送请求以获取数据。获取数据后，它被分配给一个公共(public)变量并用于显示数据。我如何为它编写测试？我需要模拟 HttpClient 吗？还是我必须提供所有 @Input 元素，然后像往常一样发出请求？但在那种情况下，我需要有真实的数据供后端在数据库中查找。

我尝试用谷歌搜索这个特定问题，但似乎找不到任何东西。我确实找到了如何模拟请求，但当它们在 ngOnInit() 中时却找不到。我将在下面添加所有必要的代码。

组件:

enum Nav {
  General = 'General',
  SSL = 'SSL',
  Routes = 'Routes',
  Statistics = 'Statistics'
};

@Component({
  selector: 'app-mod-route-properties',
  templateUrl: './mod-route-properties.component.html',
  styleUrls: ['./mod-route-properties.component.scss']
})
export class ModRoutePropertiesComponent implements OnInit {

  @Input()
  title: string;

  @Input()
  resourceAddress: ResourceAddress;

  @Input()
  wgsKey: string;

  public emsRouteInfoData: EmsRouteInfoData;

  public sideMenuItems = Object.values(Nav);
  public active: string;
  Nav = Nav;

  constructor(
    private modRoutePropertiesService: ModRoutePropertiesService
  ) {
  }

  ngOnInit() {
    this.active = Nav.General;
    this.modRoutePropertiesService.getRouteProperties(this.resourceAddress, this.wgsKey).subscribe((res: EmsRouteInfoData) => {
      this.emsRouteInfoData = res;
    }, err => {
      console.log(err);
    });
  }
}

服务:

@Injectable()
export class ModRoutePropertiesService {

    constructor(
        private urlService: UrlService,
        private serverSettingsService: ServerSettingsService,
        private http: HttpClient
    ) { }

    public getRouteProperties(resourceAddress: ResourceAddress, wgsKey: string) {
        let token = this.urlService.getTokenByKey(wgsKey);
        let url = this.serverSettingsService.getRequestUrl('/route/properties');

        let headers = { 'x-access-token': token };
        let params = {
            manager: resourceAddress.manager,
            node: resourceAddress.node,
            qmgr: resourceAddress.qmgr,
            route: resourceAddress.objectName
        };
        const rq = { headers: new HttpHeaders(headers), params: params };

        return this.http.get<EmsRouteInfoData>(url, rq);
    }
}

self 测试:

describe('ModRoutePropertiesComponent', () => {
    let component: ModRoutePropertiesComponent;
    let fixture: ComponentFixture<ModRoutePropertiesComponent>;
    let httpMock: HttpTestingController;

    beforeEach(async(() => {
        TestBed.configureTestingModule({
            imports: [
                FormsModule,
                HttpClientTestingModule,
                NgbModule.forRoot(),
                RouterModule
            ],
            declarations: [
                AppComponent,
                ModRoutePropertiesComponent,
                ModalTitleComponent,
                ModRoutePropertiesGeneralComponent,
                ModRoutePropertiesSslComponent,
                ModRoutePropertiesRoutesComponent,
                ModRoutePropertiesStatisticsComponent,
                ModRoutePropertiesRouteSelectorComponent
            ],
            providers: [
                ModRoutePropertiesService,
                UrlService,
                TabsService,
                {
                    provide: Router,
                    useClass: class { navigate = jasmine.createSpy('tab'); }
                },
                NgbActiveModal,
                ServerSettingsService,
                ModErrorsDisplayService,
                ModalWindowService,
                LoadingIndicatorService
            ]
        })
            .compileComponents();
    }));

    beforeEach(() => {
        fixture = TestBed.createComponent(ModRoutePropertiesComponent);
        component = fixture.componentInstance;
        httpMock = TestBed.get(HttpTestingController);
        fixture.detectChanges();
    });

    it('should create', () => {
        expect(component).toBeTruthy();
    });

    it(`should init 'active'`, () => {
        expect(component.active).toBeDefined();
        expect(component.active).toEqual(component.Nav.General);
    });


    it(`should have initialized 'emsRouteInfoData'`, async(() => {
        expect(component.emsRouteInfoData).toBeDefined();
    }));
});

Answer 1

我确实找到了解决方案。因此，为了测试 ngOnInit 方法内部的请求调用，您需要在调用 ngOnInit 之前监视该特定请求函数。与 spyOn(service, 'function').and.returnValue(Observable.of(object)) 一起模拟请求调用并返回您指定的数据。
为此，我删除了 beforeEach() 测试 stub 上的 fixture.detectChanges()。 detechChanges() 会触发组件的变更检测周期。之后，这就是我的 beforeEach() 的样子:

beforeEach(() => {
        fixture = TestBed.createComponent(ModRoutePropertiesComponent);
        component = fixture.componentInstance;

        resourceAddress = new ResourceAddress();
        resourceAddress.node = 'Node';
        resourceAddress.manager = 'MANAGER';
        resourceAddress.qmgr = 'T1';
        resourceAddress.objectName = 'TestRoute';

        // setting inputs
        component.resourceAddress = resourceAddress;
        component.title = title;
        component.wgsKey = wgsKey;
    });

然后，在模拟调用所需函数 getRouteProperties 之后，我将 detectChanges() 移至特定测试用例。

it(`should have initialized 'emsRouteInfoData'`, async(() => {
        // needs 'Observable.of()' to simulate real Observable and subscription to it
        spyOn(service, 'getRouteProperties').and.returnValue(Observable.of(dummyRoute));
        // start ngOnInit
        fixture.detectChanges();
        expect(service.getRouteProperties).toHaveBeenCalled();
        expect(component.emsRouteInfoData).toBeDefined();
    }));