测试发出延迟动作或不发出任何内容的 NGRX 效果

问题描述

我有一个 NGRX 效果 - 根据状态 - 发出延迟的动作或不发出任何动作。 我想编写一个测试，涵盖这两种情况。

效果如下：

myEffect$ = createEffect(() =>
  this.actions$.pipe(
    ofType(MyAction),filter(state => state.foo === false),delay(4000),map(state => myOtherAction())
  )
);

测试它应该发出具有延迟的 otherAction 的情况：

describe('emit my action',() => {
   const action = MyAction();

   it('should return a stream with myOtherAction',() => {
      const scheduler = getTestScheduler();
      scheduler.run(helpers => {
        // build the observable with the action
        actions = hot('-a',{ a: action });

        // define what is the expected outcome of the effect
        const expected = {
           b: MyOtherAction()
        };
        helpers.expectObservable(effects.myEffect$).toBe('- 4000ms b',expected);
      });
   });
});

但我不知道如何测试另一个状态，它应该不发出另一个动作（流的长度为零）：

   it('should return an empty stream',() => {
      store.setState({
        myFeature: {
           foo: true
        }
      });
      // ???
   });

请帮忙:)

解决方法

这将很难做到，因为过滤器会阻止效果返回可观察的。

选项 1： // 无论您在何处调度 MyAction，仅当创建的操作的 foo 属性为 true 时才调度它

选项 2： // 改变效果结构返回空

import { EMPTY } from 'rxjs';
....
myEffect$ = createEffect(() =>
  this.actions$.pipe(
    ofType(MyAction),delay(4000),map(state => state.foo ? myOtherAction() : EMPTY)
  )
);

测试：

import { EMPTY } from 'rxjs';
....
describe('emit my action',() => {
   const action = MyAction();
   action.foo = false; // set foo property to false

   it('should return a stream with myOtherAction',() => {
      const scheduler = getTestScheduler();
      scheduler.run(helpers => {
        // build the observable with the action
        actions = hot('-a',{ a: action });

        // define what is the expected outcome of the effect
        const expected = {
           b: EMPTY // assert now it is empty
        };
        helpers.expectObservable(effects.myEffect$).toBe('- 4000ms b',expected);
      });
   });
})

,

由于 AliF50 的提示，我将链中的 filter（阻止 Observable 发出）替换为“Noop Action”（= 没有任何侦听器的正常操作）。因此，我没有检查过滤器中的 foo 属性，而是返回映射中的 noopAction，当 foo 为真时，返回 otherAction 时为假。

效果：

myEffect$ = createEffect(() =>
  this.actions$.pipe(
    ofType(MyAction),//filter(state => state.foo === false),map(state => state.foo !== false ? noopAction() : myOtherAction())
  )
);

测试：

describe('emit my action',() => {
  const action = MyAction();

  it('should return a stream with myOtherAction',() => {
    const scheduler = getTestScheduler();
    scheduler.run(helpers => {
      // build the observable with the action
      actions = hot('-a',{ a: action });
      // define what is the expected outcome of the effect
      const expected = {
        b: MyOtherAction()
      };
      helpers.expectObservable(effects.myEffect$).toBe('- 4000ms b',expected);
    });
  });

  it('should return a stream with noop action as foo is true',() => {
    store.setState({
      myFeature: {
        foo: true
      }
    });
    const scheduler = getTestScheduler();
    scheduler.run(helpers => {
      // build the observable with the action
      actions = hot('-a',{ a: action });
      // define what is the expected outcome of the effect
      const expected = {
        b: NoopAction()
      };
      helpers.expectObservable(effects.myEffect$).toBe('- 4000ms b',expected);
    });
  });

});