Redux How to update the store in unit tests?

configureMockStore is a factory that is used to configure a mock store by applying the specified middlewares. This factory returns a mockStore function.

The mockStore function itself returns an instance of the configured mock store. It doesn't change state through actions; instead it just records which actions were passed. This is because it's a utility tool to create unit tests and not "integration" (state + component) tests.

Nonetheless, you can simulate a state change. mockStore accepts a function, so you could do the following:

import configureMockStore from 'redux-mock-store';const middlewares = [];const mockStore = configureMockStore(middlewares);let state = {  players: {    'audio-player-1': { paused: false }  }};const store = mockStore(() => state);

Then in your tests, you can do:

state = NEW_STATE;// now you need to make the components update the state.// so you can dispatch any action so the mock store will notify the subscribersstore.dispatch({ type: 'ANY_ACTION' }); 

What you can do is use a real store in your test. First, create a reducer function:

const reducer = (state, action) => {  if (action.type === actionTypes.player.UPDATE_OPTION) {    return {      ...state,      players: {        ...state.players,        [action.id]: {          ...state.players[action.id],          [action.key]: action.value,        },      },    };  }  return state;};

(Note, if you're ok with not preserving other state in this test you could simplify the above and just return a new state.)

Then create a store with that reducer and the initial state:

import { createStore } from 'redux';const store = createStore(reducer, {  players: {    'audio-player-1': { paused: false }  }});

With that, your dispatch with updateOption should result in the new state.

It seems now that thanks to a pr by @catarinasoliveira that you can provide your real reducer which will update the store accordingly. It's in master but I don't know if it's in npm yet, or frankly if it does what I just said, but I'm about to try it out and will report back