Redux Quick Start Guide

Testing reducers

A reducer is a function that returns the new state after applying the action to the previous state. Testing a reducer is no different from testing action creators. Let's create our reducers and the corresponding Jest file. We'll save our reducer file as reducers.js:

import { ADD_NEW_DOCTOR } from "./actionTypes";const initialState = [ {   newDoctorData: {},   completed: false }];export default function addDoctor(state = initialState, action) { switch (action.type) {   case ADD_NEW_DOCTOR:     return [       {         completed: false,         data: action.newDoctorData       },       ...state     ];   default:     return state; }}

Our action types will be saved as actionTypes.js:

export const ADD_NEW_DOCTOR = "ADD_NEW_DOCTOR";

Our test file will be saved in the __tests__ folder, ...