Fetch-mock don't work in version 3.2.0 redux-api-middleware test

I use the latest version of redux-api-middleware and i do the same test of documentation but the fetch mock don't work. The request it's made to real server.

import configureMockStore from 'redux-mock-store'
import { apiMiddleware } from 'redux-api-middleware'
import thunk from 'redux-thunk'
import fetchMock from 'fetch-mock'

import {getUser} from './user'

const middlewares = [ thunk, apiMiddleware ]
const mockStore = configureMockStore(middlewares)

describe('async user actions', () => {
  // If we have several tests in our test suit, we might want to
  // reset and restore the mocks after each test to avoid unexpected behaviors
  afterEach(() => {
    fetchMock.reset()
    fetchMock.restore()
  })

  it('should dispatch USER_SUCCESS when getUser is called', () => {
    // We create a mock store for our test data.
    const store = mockStore({})

    const body = {
      email: 'EMAIL',
      username: 'USERNAME'
    }
    // We build the mock for the fetch request.
    // beware that the url must match the action endpoint.
    fetchMock.getOnce(`https://hostname/api/users/`, {body: body, headers: {'content-type': 'application/json'}})
    // We are going to verify the response with the following actions
    const expectedActions = [
      {type: actions.USER_REQUEST},
      {type: actions.USER_SUCCESS, payload: body}
    ]
    return store.dispatch(actions.getUser()).then(() => {
      // Verify that all the actions in the store are the expected ones
      expect(store.getActions()).toEqual(expectedActions)
    })
  })
})

and i use the use next template to do the actions creators:

export const USER_REQUEST = '@@user/USER_REQUEST'
export const USER_SUCCESS = '@@user/USER_SUCCESS'
export const USER_FAILURE = '@@user/USER_FAILURE'

export const getUser = () => createAction({
  endpoint: 'https://hostname/api/users/',
  method: 'GET',
  headers: { 'Content-Type': 'application/json' },
  types: [
    USER_REQUEST,
    USER_SUCCESS,
    USER_FAILURE
  ]
})

I use the version of redux-api-middleware 3.2.0 and fetch-mock 9.0.0-beta.2, to perform the tests i use the version of cypress 4.0.1. If someone can help, i be glad for this. Thanks