Unit testing async action creators

action.js

/*
 * Actions
 */
export const FETCHING_USER_FROM_API = 'FETCHING_USER_FROM_API';
export const FETCHED_USER_FROM_API = 'FETCHED_USER_FROM_API';
export const FETCHED_USER_ERROR = 'FETCHED_USER_ERROR';

/*
 * Action creators
 */
export function fetchingUserFromApi() {
  return {
    type: FETCHING_USER_FROM_API,
    data: {
      isLoading: true,
      isError: false
    }
  }
}

export function fetchedUserFromApi(data) {
  return {
    type: FETCHED_USER_FROM_API,
    data: {
      isLoading: false,
      isError: false,
      ...data
    }
  }
}

export function fetchedUserFromApiError() {
  return {
    type: FETCHED_USER_ERROR,
    data: {
      isLoading: false,
      error: true
    }
  }
}

/*
 * Async actions 
 */
export function fetchMe() {
  return dispatch => 
    fetch(`/me`, { method: 'GET' })
      .then(res => res.json())
      .then(data => dispatch(fetchedUserFromApi(data)))
};

actions.test.js

import { 
  FETCHING_USER_FROM_API,
  FETCHED_USER_FROM_API,
  FETCHED_USER_ERROR,
  fetchingUserFromApi,
  fetchedUserFromApi,
  fetchedUserFromApiError,
  fetchMe
} from '../actions';
import configureMockStore from 'redux-mock-store';
import thunk from 'redux-thunk';
import fetchMock from 'fetch-mock';

let mockStore;
let store;

beforeEach(() => {
  mockStore = configureMockStore([thunk]);
  store = mockStore({});
});

describe('actions.test.js', () => {
  test('fetchingUserFromApi returns action', () => {
    expect(fetchingUserFromApi()).toEqual({
      type: FETCHING_USER_FROM_API,
      data: {
        isLoading: true,
        isError: false
      }
    });
  });

  test('fetchedUserFromApi returns action', () => {
    const data = {
      user: {
        name: 'test',
        level: 0
      }
    };

    expect(fetchedUserFromApi(data)).toEqual({
      type: FETCHED_USER_FROM_API,
      data: {
        isLoading: false,
        isError: false,
        user: {
          name: 'test',
          level: 0
        }
      }
    });
  });

  test('fetchedUserFromApiError returns action', () => {
    expect(fetchedUserFromApiError()).toEqual({
      type: FETCHED_USER_ERROR,
      data: {
        isLoading: false,
        error: true
      }
    });
  });

  test('fetchMe dispatches FETCHED_USER_FROM_API action', () => {
    fetchMock.getOnce('/me', {
      body: {},
      headers: { 'content-type': 'application/json' }
    });

    const expected = [
      {
        data: {
          isError: false,
          isLoading: false
        },
        type: "FETCHED_USER_FROM_API"
      }
    ];

    return store.dispatch(fetchMe()).then(() => {
      expect(store.getActions()).toEqual(expected)
    });
  });

  test('FETCHED_USER_FROM_API action has correct data from API', () => {
    fetchMock.getOnce('/me', {
      body: {
        username: 'test',
        email: '[email protected]'
      },
      headers: { 'content-type': 'application/json' }
    });

    const expected = [
      {
        data: {
          isError: false,
          isLoading: false,
          username: 'test',
          email: '[email protected]'
        },
        type: "FETCHED_USER_FROM_API"
      }
    ];

    return store.dispatch(fetchMe()).then(() => {
      expect(store.getActions()).toEqual(expected)
    });
  });
});