Gleb Bahmutov PRO
JavaScript ninja, image processing expert, software quality fanatic
Painless testing for React applications
ReactJS Boston
C / C++ / C# / Java / CoffeeScript / JavaScript / Node / Angular / Vue / Cycle.js / functional
EveryScape
virtual tours
MathWorks
MatLab on the web
Kensho
finance dashboards
8 people. Atlanta, Philly, Boston, LA
Fast, easy and reliable testing for anything that runs in a browser
E2E
integration
unit
Smallest pieces
Testing Pyramid △
Unit tests pass...
E2E
integration
unit
Component
(enzyme with full rendering)
E2E
integration
unit
Website
You go to a dealership to take a new car for a test drive, not to measure its wheels
planning
coding
deploying
staging / QA
production
E2E
E2E
Users
planning
coding
deploying
staging / QA
production
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E2E
E2E
Users
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🐞$0
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planning
coding
deploying
staging / QA
production
💵
E2E
E2E
Users
💵
🐞$0
💵
💰
💰
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Answer: E2E
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Let's test!
- Open and control real browser
Your tests
Selenium
Driver
FF, Chrome , IE
Let's test!
- Open and control real browser
Your tests
FF, Chrome , IE
slow, flaky, unreliable tests
Let's test!
Your tests
FF, Chrome , IE
Let's test!
Your tests
Headless browser
What is happening?
$ npm install -D cypress
- Win / Mac / Linux
- MIT License
- OSS https://github.com/cypress-io/cypress
- http://on.cypress.io/introduction-to-cypress
// ui-spec.js
it('loads the app', () => {
cy.visit('https://some-url.com')
cy.get('.todoapp').should('be.visible')
})const visit = () => cy.visit('/')
describe('UI', () => {
beforeEach(resetDatabase)
beforeEach(visit)
context('basic features', () => {
it('starts with zero items', () => {
cy.get('.todo-list')
.find('li')
.should('have.length', 0)
})
})
})
Cypress demo
- Opening a page
- Typical test
- Failing test
- API and documentation
- Recording tests
- CI setup
Sliding down the testing pyramid
E2E
integration
unit
Need:
- real browser (DOM, storage, ...)
- state cleanup between tests
- stubbing server
E2E
integration
unit
Need:
- real browser (DOM, storage, ...)
- state cleanup between tests
- stubbing server
WAIT A MINUTE!
Interact, inspect, use
cypress-vue-unit-test
cypress-react-unit-test
cypress-svelte-unit-test
cypress-hyperapp-unit-test
...
$ npm install -D cypress cypress-react-unit-testimport { HelloSpider } from './src/hello-spiderman.jsx'
import React from 'react'
import { mount } from 'cypress-react-unit-test'
React component test demo with Cypress
it('works', () => {
mount(<HelloSpider />)
// start testing!
cy.contains('Hello Spider-man!')
})
E2E
integration
unit
Why are they called
cypress-<X>-unit-test ?!
Cypress for Integration
E2E
integration
unit
function add(a, b) {
return a + b
}add(a, b)
outputs
inputs
a, b
returned value
it('adds', () => {
expect(add(2,3)).to.equal(5)
})Unit test
function add(a, b) {
const el = document.getElementById('result')
el.innerText = a + b
}add(a, b)
outputs
inputs
a, b
DOM
it('adds', () => {
add(2,3)
const el = document.getElementById('result')
expect(el.innerText).to.equal('5')
})Integration test?
function add() {
const {a, b} =
JSON.parse(localStorage.getItem('inputs'))
const el = document.getElementById('result')
el.innerText = a + b
}add(a, b)
outputs
inputs
localStorage
DOM
it('adds', () => {
localStorage.setItem('inputs') =
JSON.stringify({a: 2, b: 3})
add()
const el = document.getElementById('result')
expect(el.innerText).to.equal('5')
})Integration test?
component
outputs
inputs
DOM,
localStorage,
location,
HTTP,
cookies
WW, SW,
...
DOM,
localStorage,
location,
HTTP,
cookies
WW, SW,
...
component
outputs
inputs
DOM,
localStorage,
location,
HTTP,
cookies
WW, SW,
...
DOM,
localStorage,
location,
HTTP,
cookies
WW, SW,
...
Unit test
Set up
Assert
Mount
E2E
unit
it('logs user in', () => {
cy.visit('page.com')
cy.get('#login').click()
})E2E
unit
it('logs user in', () => {
mount(LoginComponent)
cy.get('#login').click()
})E2E
unit
Use same syntax, life cycle and Cypress API
🔋🔋🔋🔋🔋🔋🔋🔋🔋🔋🔋
Thank you
@cypress_io
@bahmutov
Painless Testing for React Applications
By Gleb Bahmutov
Painless Testing for React Applications
Testing is hard. End to end testing is really hard. But maybe it is hard because our tools are not up to task. What if we could redesign the testing experience from the ground up to be fast, useful and effective? Let me show you how to quickly test a React application using Cypress.io - an open source modern test runner that replaces Selenium. Don't believe the hype - come see Cypress demo for yourself, and I guarantee you will start writing tests. Presented at ReactJS Boston meetup April 2018. Video at https://www.youtube.com/watch?v=lgurVvQsOTY
