vzaidman

const increaseBy = makeActionCreator('INCREASE_BY')

vzaidman

import {increaseBy} from 'actions'
export const countReducer = makeReducer(increaseBy,
 (state, {payload}) => state + payload,
 {defaultState: 100}
)

vzaidman

const state1 = countReducer(undefined, {TYPE: '@@redux/INIT'})
// the initial state was set in defaultState and its value is 100
// ⇒ state1 === 100

const state2 = countReducer(state1, increaseBy(100))
// ⇒ state2 === 200

const state3 = countReducer(state2, increaseBy(-500))
// ⇒ state3 === -300

vzaidman

{
  profile: {
    data: undefined,
    loading: false
  },
  customers: {
    data: undefined,
    loading: false
  },
  orders: {

vzaidman

{
  profile: {
    data: { id: '...', name: '...', /** ...user profile **/ },
    loading: false
  },
  customers: {
    data: [ 'customer0', 'customer1', /** ...customers array **/ ],
    loading: false
  },
  orders: {

vzaidman

{
  profile: {
    data: null,
    loading: false
  },
  customers: {
    data: null,
    loading: false
  },
  orders: {

vzaidman

describe('calculator', function() {
  // describes a module with nested "describe" functions
  describe('add', function() {
    // specify the expected behavior
    it('should add 2 numbers', function() {
       //Use assertion functions to test the expected behavior
       ...  
    })
  })
})

vzaidman

// Chai expect (popular)
expect(foo).to.be.a('string')
expect(foo).to.equal('bar')

// Jasmine expect (popular)
expect(foo).toBeString()
expect(foo).toEqual('bar')

// Chai assert
assert.typeOf(foo, 'string')

vzaidman

class Child {
  ...
  execute(arg) { ... }
  ...
}
  
class Father {
  constructor() {
    this.child = new Child()
  }

vzaidman

// make sure User.fetch to respond with a mocked user
// instead of making an actual ajax request
const stub = sinon
  .stub(Users.prototype, 'fetch')
  .resolves([
    { id: 0, name: 'David', score: 0 },
    { id: 1, name: 'Adam', score: 20 }
  ])

it('Should add score to a user', done => {