redux-mock-store

What is redux-mock-store?

The redux-mock-store npm package is used for testing Redux async action creators and middleware. The package provides a mock store for your tests with a state that you can control. It allows you to dispatch actions and test the state of the store after they are dispatched without having to interact with the real Redux store.

What are redux-mock-store's main functionalities?

Creating a mock store

This code sample demonstrates how to create a mock store using redux-mock-store. The `configureStore` function is imported from the package, and then it is called with an array of middlewares (empty in this case). Finally, the `mockStore` function is used to create an instance of the store with an initial state.

const configureStore = require('redux-mock-store');
const middlewares = [];
const mockStore = configureStore(middlewares);
const store = mockStore({ todos: [] });

Dispatching actions and checking dispatched actions

This code sample shows how to dispatch an action to the mock store and then retrieve the dispatched actions using `getActions` method. The `expect` function is used to assert that the dispatched actions are as expected.

store.dispatch({ type: 'ADD_TODO', text: 'Test Redux' });
const actions = store.getActions();
expect(actions).toEqual([{ type: 'ADD_TODO', text: 'Test Redux' }]);

Resetting the state of the store

This code sample illustrates how to reset the state of the mock store. The `clearActions` method is used to clear all actions in the store, and then `getActions` is used to verify that the store's actions have been reset.

store.clearActions();
const actions = store.getActions();
expect(actions).toEqual([]);

Other packages similar to redux-mock-store

jest-redux

jest-redux is another testing utility that provides a set of Jest matchers for Redux. It is similar to redux-mock-store in that it helps with testing Redux-related code, but it is more focused on integrating with Jest and providing a different set of utilities for assertions.

README

Deprecation notice

The Redux team does not recommend testing using this library. Instead, see our docs for recommended practices, using a real store.

Testing with a mock store leads to potentially confusing behaviour, such as state not updating when actions are dispatched. Additionally, it's a lot less useful to assert on the actions dispatched rather than the observable state changes.

You can test the entire combination of action creators, reducers, and selectors in a single test, for example:

it('should add a todo', () => {
  const store = makeStore() // a user defined reusable store factory

  store.dispatch(addTodo('Use Redux'))

  expect(selectTodos(store.getState())).toEqual([
    { text: 'Use Redux', completed: false }
  ])
})

This avoids common pitfalls of testing each of these in isolation, such as mocked state shape becoming out of sync with the actual application.

redux-mock-store

A mock store for testing Redux async action creators and middleware. The mock store will create an array of dispatched actions which serve as an action log for tests.

Please note that this library is designed to test the action-related logic, not the reducer-related one. In other words, it does not update the Redux store. If you want a complex test combining actions and reducers together, take a look at other libraries (e.g., redux-actions-assertions). Refer to issue #71 for more details.

Install

npm install redux-mock-store --save-dev

Or

yarn add redux-mock-store --dev

Usage

Synchronous actions

The simplest usecase is for synchronous actions. In this example, we will test if the addTodo action returns the right payload. redux-mock-store saves all the dispatched actions inside the store instance. You can get all the actions by calling store.getActions(). Finally, you can use any assertion library to test the payload.

import configureStore from 'redux-mock-store' //ES6 modules
const { configureStore } = require('redux-mock-store') //CommonJS

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

// You would import the action from your codebase in a real scenario
const addTodo = () => ({ type: 'ADD_TODO' })

it('should dispatch action', () => {
  // Initialize mockstore with empty state
  const initialState = {}
  const store = mockStore(initialState)

  // Dispatch the action
  store.dispatch(addTodo())

  // Test if your store dispatched the expected actions
  const actions = store.getActions()
  const expectedPayload = { type: 'ADD_TODO' }
  expect(actions).toEqual([expectedPayload])
})

Asynchronous actions

A common usecase for an asynchronous action is a HTTP request to a server. In order to test those types of actions, you will need to call store.getActions() at the end of the request.

import configureStore from 'redux-mock-store'
import thunk from 'redux-thunk'

const middlewares = [thunk] // add your middlewares like `redux-thunk`
const mockStore = configureStore(middlewares)

// You would import the action from your codebase in a real scenario
function success() {
  return {
    type: 'FETCH_DATA_SUCCESS'
  }
}

function fetchData() {
  return (dispatch) => {
    return fetch('/users.json') // Some async action with promise
      .then(() => dispatch(success()))
  }
}

it('should execute fetch data', () => {
  const store = mockStore({})

  // Return the promise
  return store.dispatch(fetchData()).then(() => {
    const actions = store.getActions()
    expect(actions[0]).toEqual(success())
  })
})

API

configureStore(middlewares?: Array) => mockStore: Function

Configure mock store by applying the middlewares.

mockStore(getState?: Object,Function) => store: Function

Returns an instance of the configured mock store. If you want to reset your store after every test, you should call this function.

store.dispatch(action) => action

Dispatches an action through the mock store. The action will be stored in an array inside the instance and executed.

store.getState() => state: Object

Returns the state of the mock store.

store.getActions() => actions: Array

Returns the actions of the mock store.

store.clearActions()

Clears the stored actions.

store.subscribe(callback: Function) => unsubscribe: Function

Subscribe to the store.

store.replaceReducer(nextReducer: Function)

Follows the Redux API.

Old version (< 1.x.x)

https://github.com/arnaudbenard/redux-mock-store/blob/v0.0.6/README.md

Versions

The following versions are exposed by redux-mock-store from the package.json:

• main: commonJS Version
• module/js:next: ES Module Version
• browser : UMD version

License

The MIT License