unit-testing - 带有 ngrx 的 angular 2 组件 - 运行单元测试时出错

Question

我正在从事 Angular 2 项目，使用 ngrx(用于 Redux 逻辑)和 rxjs(用于可观察)。

现在我尝试通过运行自动创建的 .spec.ts 文件来测试项目。

部分测试失败，所有测试都是使用 Store(来自 ngrx)的组件测试。 这是其中之一:

import { async, ComponentFixture, TestBed } from '@angular/core/testing';
import { By } from '@angular/platform-browser';
import { DebugElement } from '@angular/core';

import { MyComponent } from './overlay-menu-item.component';

describe('MyComponent', () => {
let component: MyComponent;
let fixture: ComponentFixture<MyComponent>;

beforeEach(async(() => {
  TestBed.configureTestingModule({
    declarations: [ MyComponent ],
  })
  .compileComponents();
}));

beforeEach(() => {
  fixture = TestBed.createComponent(MyComponent);
  component = fixture.componentInstance;
  fixture.detectChanges();
});

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

我查了一下问题，错误是:

No provider to Store

所以我补充:(我用jasmine做测试)

 beforeEach(async(() => {
TestBed.configureTestingModule({
  declarations: [ MyComponent ],
  providers: [Store]
 })
 .compileComponents();
}));

现在我得到了其他错误:

No provider for StateObservable

所以我补充说:

  beforeEach(async(() => {
TestBed.configureTestingModule({
  declarations: [ MyComponent ],
  providers: [Store, StateObservable]
 })
 .compileComponents();
}));

但现在我遇到了新的错误，我不知道如何处理它:

Failed: Can't resolve all parameters for StateObservable: (?).
    Error: Can't resolve all parameters for StateObservable: (?).
        at syntaxError [mywebprojectPath]/node_modules/@angular/compiler/@angular/compiler.es5.js:1689:22)

我该怎么办？

Answer 1

你应该创建一个 MockStore .

简而言之:

import { Action } from '@ngrx/store';
import { Observable } from 'rxjs/Observable';
import { Subject } from 'rxjs/Subject';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
import { map } from 'rxjs/operator/map';

export class MockStore<T> extends BehaviorSubject<T> {  
  constructor(private _initialState: T) {
    super(_initialState);
  }
  dispatch = (action: Action): void => {
  }

  select = <T, R>(pathOrMapFn: any, ...paths: string[]): Observable<R> => {
    return map.call(this, pathOrMapFn);
  }
}

然后您可以在测试中提供 mockStore:

const initialState = {...};
TestBed.configureTestingModule({
  ...
  providers:[
    {provide:Store, useValue: new MockStore(initialState)}
  ]
  ...
})