How can I test Thunk actions with Jest?

user_6203606 0
Viewed 11122

I'm new to unit testing Redux-Thunk async actions using Jest.

Here is my code:

export const functionA = (a, b) => (dispatch) => {
    dispatch({ type: CONSTANT_A, payload: a });
    dispatch({ type: CONSTANT_B, payload: b });
}

How can I test this function using Jest?

redux-thunk redux jestjs unit-testing
3 Answers

Also, for more more convenience, you can use this module: https://www.npmjs.com/package/redux-thunk-tester

Example:

import React from 'react';
import {createStore, applyMiddleware, combineReducers} from 'redux';
import {reducer} from './example';
import ReduxThunkTester from 'redux-thunk-tester';
import thunk from 'redux-thunk';

const request = (ms) => new Promise((resolve) => {
  setTimeout(() => resolve('success response'), ms);
});

const resultRequestAction = (value) => ({ type: SOME_BACKEND_REQUEST, payload: value });
const toggleLoadingAction = (value) => ({ type: TOGGLE_LOADING, payload: value });

const asyncThunkWithRequest = () => async (dispatch) => {
  try {
    dispatch(toggleLoadingAction(true));
    const result = await request(200);
    dispatch(resultRequestAction(result));
  } finally {
    dispatch(toggleLoadingAction(false));
  }
};

const createMockStore = () => {
  const reduxThunkTester = new ReduxThunkTester();

  const store = createStore(
    combineReducers({exampleSimple: reducer}),
    applyMiddleware(
      reduxThunkTester.createReduxThunkHistoryMiddleware(),
      thunk
    ),
  );

  return {reduxThunkTester, store};
};

describe('Simple example.', () => {
  test('Success request.', async () => {
    const {store, reduxThunkTester: {getActionHistoryAsync, getActionHistoryStringifyAsync}} = createMockStore();

    store.dispatch(asyncThunkWithRequest());

    const actionHistory = await getActionHistoryAsync(); // need to wait async thunk (all inner dispatch)

    expect(actionHistory).toEqual([
      {type: 'TOGGLE_LOADING', payload: true},
      {type: 'SOME_BACKEND_REQUEST', payload: 'success response'},
      {type: 'TOGGLE_LOADING', payload: false},
    ]);

    expect(store.getState().exampleSimple).toEqual({
      loading: false,
      result: 'success response'
    });

    console.log(await getActionHistoryStringifyAsync({withColor: true}));
  });
});
user_104294400

I recommend you to write something like this to avoid async problems:

return store
  .dispatch(actionCreators.login({}))
  .then(() => expect(store.getActions()).toEqual(expectedActions));
user_115056160
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