Angular 5單元測試：“無法讀取Injector中未定義的屬性'get'”

Question

我正在使用Karma-Jasmines為您的Web應用程序編寫單元測試Angular 5。 我使用Injector注入服務。

1. 創建InjectableObject方法：

    import { Injector } from '@angular/core'; let appInjectorRef: Injector; export const InjectableObject = (injector?: Injector): Injector => { if (injector) { appInjectorRef = injector; } return appInjectorRef; }; 

2. 創建BaseComponent類：

    import { InjectableObject } from './injectableobject.base'; import { MyDataService} from '../services/mydata.service'; interface IBaseComponentOptions { hotkey?: boolean; tableName?: string } export class BaseComponent implements OnInit, OnDestroy, AfterContentInit{ constructor(private opt?: IBaseComponentOptions) { const _injector = InjectableObject(); this._myDataService = _injector.get(MyDataService); } } 

3. 創建一個從BaseComponent擴展的組件：

    @Component({ selector: 'app-header', templateUrl: './header.component.html', styleUrls: ['./header.component.scss'] }) export class HeaderComponent extends BaseComponent implements OnInit { constructor( private dataService: MyDataService, ){super()} } 

4. 創建文件單元測試：從“”導入{MessageService}; 從“”導入{HeaderComponent};

    describe('HeaderComponent', () => { let component: HeaderComponent; let fixture: ComponentFixture<HeaderComponent>; let backend: MockBackend; beforeEach(async(() => { TestBed.configureTestingModule({ declarations: [HeaderComponent], provides: [MyDataService] }) }).compileComponents(); beforeEach(() => { fixture = TestBed.createComponent(HeaderComponent); component = fixture.componentInstance; fixture.detectChanges(); }); it('should create', () => { expect(component).toBeTruthy(); }); }); 

但是當我進行測試時，我得到了：

TypeError：無法讀取未定義的屬性“ get”

在“ this._myDataService = _injector.get（MyDataService）;”處 在BaseComponent中。

我不知道編寫單元測試來通過這種情況。 請大家幫我！ 謝謝大家！

Answer 1

它與異步調用有關.....

用fakeAsync調用包裝該測試用例。

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

然后從@angular/core/testing導入fakeAsync