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单元测试NGRX效果以确保调用服务方法-不工作

ngrx-effects ngrx jestjs unit-testing angular

codeepic zetriks · 技术社区 · 5 年前

我正在使用NGRX^7.0.0版本。这是我的NGRX效果课程:

import { Injectable } from '@angular/core';
import { ApisService } from '../apis.service';
import { Effect, Actions, ofType } from '@ngrx/effects';
import { Observable } from 'rxjs';
import { ApisActionTypes, ApisFetched } from './apis.actions';
import { mergeMap, map } from 'rxjs/operators';

@Injectable()
export class ApisEffects {

  constructor(private apisS: ApisService, private actions$: Actions) { }

  @Effect()
  $fetchApisPaths: Observable<any> = this.actions$.pipe(
    ofType(ApisActionTypes.FetchApisPaths),
    mergeMap(() =>
      this.apisS.fetchHardCodedAPIPaths().pipe(
        map(res => new ApisFetched(res))
      )
    )
  );
}

这是一个简单的测试。正如你所看到的,它应该失败,但总是会过去。我在StackOverflow上也有类似的问题 How to unit test this effect (with {dispatch: false})? 但它对我不起作用,好像代码执行从未进入效果。$fetchapaths.subscribe块

import { TestBed } from '@angular/core/testing';
import { provideMockActions } from '@ngrx/effects/testing';
import { hot, cold } from 'jasmine-marbles';
import { Observable, ReplaySubject } from 'rxjs';
import { ApisEffects } from '../state/apis.effects';
import { ApisFetch, ApisFetched } from '../state/apis.actions';
import { IApiPath } from '../models';
import { convertPaths, getAPIPathsAsJson, ApisService } from '../apis.service';
import { ApisServiceMock } from './mocks';

describe('Apis Effects', () => {
  let effects: ApisEffects;
  let actions: Observable<any>;
  let apisS: ApisService;

  beforeEach(() => {
    TestBed.configureTestingModule({
      providers: [
        ApisEffects,
        provideMockActions(() => actions),
        {
          provide: ApisService,
          useClass: ApisServiceMock
        }
      ]
    });

    effects = TestBed.get(ApisEffects);
    apisS = TestBed.get(ApisService);
  });

  it('should call ApisService method() to get Api Paths', () => {
    const spy = spyOn(apisS, 'fetchHardCodedAPIPaths');

    const action = new ApisFetch();
    actions = hot('--a-', {a: action});

    effects.$fetchApisPaths.subscribe(() => {
      console.log('%c effect trigerred', 'color: orange; border: 1px solid red;');
      // expect(spy).toHaveBeenCalled();
      expect(true).toBe(false); // never fails
    });
  });
});

为了以防万一,我做了一些愚蠢的动作,下面是动作文件: 很可能我不是,因为它按预期在应用程序中工作。

import { Action } from '@ngrx/store';
import { IApiPath } from '../models';

export enum ApisActionTypes {
    FetchApisPaths = '[Apis] Fetch Paths',
    FetchedApisPaths = '[Apis] Fetched Paths'
}

export class ApisFetch implements Action {
    readonly type = ApisActionTypes.FetchApisPaths;
}

export class ApisFetched implements Action {
    readonly type = ApisActionTypes.FetchedApisPaths;
    constructor(public payload: IApiPath[]) {}
}

export type ApisActions = ApisFetch | ApisFetched;

=================编辑===================

我使用了一个来自官方NGRX文档的示例 https://ngrx.io/guide/effects/testing 现在我可以成功地进入下面的subscribe块,记录两个控制台日志,但是测试成功。这太奇怪了!我尝试从订阅块抛出错误,测试仍然成功。

it('should work also', () => {
    actions$ = new ReplaySubject(1);

    actions$.next(new ApisFetch());

    effects.$fetchApisPaths.subscribe(result => {
      console.log('will be logged');
      expect(true).toBe(false); // should fail but nothing happens - test succeeds
      console.log(' --------- after '); // doesn't get called, so the code
      // execution stops on expect above
    });
  });

1 回复 | 直到 5 年前

codeepic zetriks 5 年前

好吧,我让它工作了。为了成功测试特定的角度服务方法是否在ngrx效果中被调用,我将一个测试用例包装在 async :

  it('should call ApisService method to fetch Api paths', async () => {
    const spy = spyOn(apisS, 'fetchHardCodedAPIPaths');

    actions$ = new ReplaySubject(1);
    actions$.next(new ApisFetch());
    await effects.$fetchApisPaths.subscribe();

    expect(spy).toHaveBeenCalled();
  });

我 await effects.$fetchApisPaths.subscribe(); 阻止执行并在下一行运行测试断言。

现在当我试着跑的时候 expect(true).toBe(false); 为了测试测试是否失败,它正确地失败了。

问题中我的代码有问题(示例 ReplaySubject 在NGRX文档中 https://ngrx.io/guide/effects/testing )当断言在内部时,不可能使测试失败 .subscribe() 块。在那里发生了一些不确定的事情,我仍然不知道代码为什么会以以下方式运行:

effects.$fetchApisPaths.subscribe(result => {
  console.log('will be logged');  // 1) gets logged
  expect(true).toBe(false);       // 2) should fail
  console.log(' - after ');       // 3) doesn't get called
});

因此,代码执行将在线停止 2) ,测试用例返回正和行 3) 永远不会被处决。

因此,在包含断言的ngrx文档中的测试用例 订阅() 块将始终是绿色的,给您的测试用例一个假阳性。这就是我经历过的行为 ngrx ^7.0.0