fetchMock не реализует насмешки

Question

У меня есть тест:

import { REQUEST_JOKES, RECEIVE_JOKES_SUCCESS } from '../types/jokes'
import { fetchJokesIfNeeded } from './jokes'
import configureStore from 'redux-mock-store'
import thunk from 'redux-thunk'
import fetchMock from 'fetch-mock'
import expect from 'expect'

require('es6-promise').polyfill()
import 'isomorphic-fetch'

const middlewares = [thunk];
const mockStore = configureStore(middlewares)


const expectedActions = [{type: REQUEST_JOKES, quantity:1}, 
                         {type: RECEIVE_JOKES_SUCCESS, jokes:['Chuck Norris first job was as a paperboy. There were no survivors.']}];

describe('fetchJokes action', () => {

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

it('creates RECEIVE_JOKES_SUCCESS then fetching of jokes has been done', () => {
  fetchMock.getOnce('%', { body: {
    "type": "success",
    "value": [
      {
        "joke": "Chuck Norris first job was as a paperboy. There were no survivors."
      }
    ]
    }, headers: {'content-type': 'application/json'}})    
  const initState = {jokes:{isFetching: false, value:[]}};       
  const store = mockStore(initState);
  return store.dispatch(fetchJokesIfNeeded(1)) // Promise 
    .then(() => {
      expect(store.getActions()).toEqual(expectedActions)
    })
  }) 
}) 

npm test возвращает что-то вроде этого:

 expect(received).toEqual(expected)

Expected value to equal:
  [{"quantity": 1, "type": "REQUEST_JOKES"}, {"jokes": ["Chuck Norris first job was as a paperboy. There were no survivors."], "type": "RECEIVE_JOKES_SUCCESS"}]
Received:
  [{"quantity": 1, "type": "REQUEST_JOKES"}, {"jokes": ["Using his trademark roundhouse kick, Chuck Norris once made a fieldgoal in RJ Stadium in Tampa Bay from the 50 yard line of Qualcomm stadium in San Diego."], "type": "RECEIVE_JOKES_SUCCESS"}]

Очевидно, что fetchMock не реализует извлечение насмешек в fetchJokesIfNeeded, Следовательно, он вызывает фактический вызов извлечения. Я уже рассмотрел это средство устранения неполадок https://github.com/wheresrhys/fetch-mock/blob/master/docs/troubleshooting.md#fetch-doesnt-seem-to-be-getting-mocked устранение неисправностей.md#fetch-doesnt-seem-to-be-getting- издевались, но это не помогло.