javascript - Mock inner axios.create()

Question

I'm using jest and axios-mock-adapter to test axios API calls in redux async action creators.

I can't make them work when I'm using a axios instance that was created with axios.create() as such:

import axios from 'axios';

const { REACT_APP_BASE_URL } = process.env;

export const ajax = axios.create({
  baseURL: REACT_APP_BASE_URL,
});

which I would consume it in my async action creator like:

import { ajax } from '../../api/Ajax'

export function reportGet(data) {
  return async (dispatch, getState) => {
    dispatch({ type: REQUEST_TRANSACTION_DATA })

    try {
      const result = await ajax.post(
         END_POINT_MERCHANT_TRANSACTIONS_GET,
         data,
      )
      dispatch({ type: RECEIVE_TRANSACTION_DATA, data: result.data })
      return result.data
    } catch (e) {
      throw new Error(e);
    }
  }
}

Here is my test file:

import {
  reportGet,
  REQUEST_TRANSACTION_DATA,
  RECEIVE_TRANSACTION_DATA,
} from '../redux/TransactionRedux'
import configureMockStore from 'redux-mock-store'
import thunk from 'redux-thunk'
import { END_POINT_MERCHANT_TRANSACTIONS_GET } from 'src/utils/apiHandler'
import axios from 'axios'
import MockAdapter from 'axios-mock-adapter'

const middlewares = [thunk]
const mockStore = configureMockStore(middlewares)
const store = mockStore({ transactions: {} })

test('get report data', async () => {
  let mock = new MockAdapter(axios)

  const mockData = {
    totalSalesAmount: 0
  }

  mock.onPost(END_POINT_MERCHANT_TRANSACTIONS_GET).reply(200, mockData)

  const expectedActions = [
    { type: REQUEST_TRANSACTION_DATA },
    { type: RECEIVE_TRANSACTION_DATA, data: mockData },
  ]

  await store.dispatch(reportGet())
  expect(store.getActions()).toEqual(expectedActions)
})

And I only get one action Received: [{"type": "REQUEST_TRANSACTION_DATA"}] because there was an error with the ajax.post.

I have tried many ways to mock the axios.create to no avail without really knowing what I'm doing..Any Help is appreciated.

Answer 1

OK I got it. Here is how I fixed it! I ended up doing without any mocking libraries for axios!

Create a mock for axios in src/__mocks__:

// src/__mocks__/axios.ts

const mockAxios = jest.genMockFromModule('axios')

// this is the key to fix the axios.create() undefined error!
mockAxios.create = jest.fn(() => mockAxios)

export default mockAxios

Then in your test file, the gist would look like:

import mockAxios from 'axios'
import configureMockStore from 'redux-mock-store'
import thunk from 'redux-thunk'

// for some reason i need this to fix reducer keys undefined errors..
jest.mock('../../store/rootStore.ts')

// you need the 'async'!
test('Retrieve transaction data based on a date range', async () => {
  const middlewares = [thunk]
  const mockStore = configureMockStore(middlewares)
  const store = mockStore()

  const mockData = {
    'data': 123
  }

  /** 
   *  SETUP
   *  This is where you override the 'post' method of your mocked axios and return
   *  mocked data in an appropriate data structure-- {data: YOUR_DATA} -- which
   *  mirrors the actual API call, in this case, the 'reportGet'
   */
  mockAxios.post.mockImplementationOnce(() =>
    Promise.resolve({ data: mockData }),
  )

  const expectedActions = [
    { type: REQUEST_TRANSACTION_DATA },
    { type: RECEIVE_TRANSACTION_DATA, data: mockData },
  ]

  // work
  await store.dispatch(reportGet())

  // assertions / expects
  expect(store.getActions()).toEqual(expectedActions)
  expect(mockAxios.post).toHaveBeenCalledTimes(1)
})