Question

我有一个使用takeWhile()订阅NgRx reducer时使用select的组件。因此：

    this.store.pipe(select(reducer.getProviders))
            .takeWhile( ... )
            .subscribe(providers => {
                ...
            });

现在我要为此编写测试。目前，这是非常基本的：

    import { StoreModule, Store, Action, select, combineReducers } from '@ngrx/store';
    import { Subject } from 'rxjs/Subject';

    import * as reducer from './../../reducers';

    describe('ProviderComponent', () => {
        let component: ProviderComponent;
        let fixture: ComponentFixture<ProviderComponent>;
        let store: Store<reducer.State>;

        beforeEach(async(() => {
            const actions = new Subject<Action>();
            const states = new Subject<reducer.State>();
            store = mockStore<reducer.State>({ actions, states });

            TestBed.configureTestingModule({
                imports: [
                    StoreModule.forRoot({
                        provider: combineReducers(reducer.reducers)
                    }),
                    ...
                ],
                declarations: [
                    ProviderComponent
                ],
                providers: [
                    { provide: Store, useValue: store },
                    { provide: HAMMER_LOADER, useValue: () => new Promise(() => { return; }) }
                ]
            })
            fixture = TestBed.createComponent(ProviderComponent);
            component = fixture.componentInstance;
            component.providerCtrl = new FormControl();
            spyOn(store, 'dispatch').and.callThrough();
        }));

        describe('When provider is rendered', () => {
            beforeEach(() => {
                fixture.detectChanges();
            });

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

            it('store to be defined', async(() => {
                expect(store).toBeDefined();
            }));
        });
    });

但是当我运行它时，出现此错误：

TypeError: this.store.pipe(...).takeWhile is not a function

我不知道如何导入它！有人可以帮我吗？

Answer 1

需要在组件中导入Takewhile运算符

import 'rxjs/add/operator/takeWhile';

对于以上的rxjs 5.5，请在下面的语句中使用

import { takeWhile } from 'rxjs/operators';

Answer 2

takeWhile是可管道运算符，应包含在管道中：

this.store.pipe(
   select(reducer.getProviders),
   takeWhile( ... ) 
).subscribe(providers => {
    ...
});

角度测试因takeWhile（）而失败

2 个答案: