我有这样的reducer，使用fetch API作为它的基础最终：

export const fetchRelatedFamilies = () => {
  return (dispatch, getState) => {
    if (isEmpty(getState().relatedFamiliesById)) {
      dispatch({ type: REQUEST_RELATED_FAMILIES_BY_ID })
      new HttpRequestHelper('/api/related_families',
        (responseJson) => {
          dispatch({ type: RECEIVE_RELATED_FAMILIES_BY_ID, updates: responseJson.relatedFamiliesById })
        },  
        e => dispatch({ type: RECEIVE_RELATED_FAMILIES_BY_ID, error: e.message, updates: {} }), 
      ).get()
    }   
  }
}

HttpRequestHelper的程式码如下：https://github.com/broadinstitute/seqr/blob/master/ui/shared/utils/httpRequestHelper.js
下面是我如何尝试测试它（但它不工作）：

import configureStore from 'redux-mock-store'
import fetchMock from 'fetch-mock'
import thunk from 'redux-thunk'
import { cloneDeep } from 'lodash'
import { fetchRelatedFamilies, REQUEST_RELATED_FAMILIES_BY_ID, RECEIVE_RELATED_FAMILIES_BY_ID } from 'redux/rootReducer'

import { STATE1 } from '/shared/components/panel/fixtures.js'

describe('fetchRelatedFamilies', () => {
  const middlewares = [thunk]
  const testActionsDispatch = async (currstate, expectedActions) => {
    const store = configureStore(middlewares)(currstate)
    store.dispatch(fetchRelatedFamilies())

    // need to mimick wait for async actions to be dispatched
    //await new Promise((r) => setTimeout(r, 200));
    expect(store.getActions()).toEqual(expectedActions)
  }

  afterEach(() => {
    fetchMock.reset()
    fetchMock.restore()
  })  

  it('Dispatches correct actions when data - relatedFamiliesById - is absent in state', () => {
    const relatedFamiliesById = cloneDeep(STATE1.relatedFamiliesById)
    fetchMock
      .getOnce('/api/related_families', { body: relatedFamiliesById, headers: { 'content-type': 'application/json' } })

    STATE1.relatedFamiliesById = {}
    const expectedActions = [ 
      { type: REQUEST_RELATED_FAMILIES_BY_ID },
      { type: RECEIVE_RELATED_FAMILIES_BY_ID, updates: relatedFamiliesById }
    ]   
    testActionsDispatch(STATE1, expectedActions)
  })  
})

我在结果存储操作中没有看到{ type: RECEIVE_RELATED_FAMILIES_BY_ID, updates: relatedFamiliesById }，所以我尝试使用以下技巧：await new Promise((r) => setTimeout(r, 200));，希望这是异步fetch的问题，但它导致的是，无论预期的操作是什么，测试都会通过，就好像await后面的代码被完全忽略了一样。我不能使用store.dispatch(fetchRelatedFamilies()).then(...，可能是因为没有返回Promise，并且我得到了then access of undefined错误。我尝试从库中使用waitFor：https://testing-library.com/docs/guide-disappearance/，但是由于项目本身的性质和版本，我在安装库本身时遇到了很大的麻烦，所以我仍然需要以某种方式避免它。
因此，我唯一的问题是如何使异步reducer内部的操作出现，在本例中为{ type: RECEIVE_RELATED_FAMILIES_BY_ID, updates: relatedFamiliesById }。