Gleb Bahmutov PRO
JavaScript ninja, image processing expert, software quality fanatic
My Favorite Cypress Plugins
LambdaTest
Voices of Community
Gleb Bahmutov
Sr Director of Engineering
our planet is in imminent danger
https://lizkeogh.com/2019/07/02/off-the-charts/
+3 degrees Celsius will be the end and we are close
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- change your life
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Speaker: Gleb Bahmutov PhD
C / C++ / C# / Java / CoffeeScript / JavaScript / Node / Angular / Vue / Cycle.js / functional programming / testing
Gleb Bahmutov
Sr Director of Engineering
Lots Of Testing
AGENDA
- Don't use plugins
- The many types of plugins
- My (favorite) plugins
- cypress-map
- cypress-each
- cypress-watch-and-reload
- cypress-grep
- cypress-recurse
- cypress-data-session
- The end
$ npm install -D cypress
- Win / Mac / Linux
- MIT License
- OSS https://github.com/cypress-io/cypress
- https://on.cypress.io/introduction-to-cypress
// ui-spec.js
it('loads the app', () => {
cy.visit('http://localhost:3000')
cy.get('.todoapp').should('be.visible')
})
Mocha BDD syntax
Chai assertions
it('adds 2 todos', () => {
cy.visit('http://localhost:3000')
cy.get('.new-todo')
.type('learn testing{enter}')
.type('be cool{enter}')
cy.get('.todo-list li')
.should('have.length', 2)
})
$ npx cypress opendescribe('intercept', () => {
it('returns different fruits every 30 seconds', () => {
cy.clock()
// return difference responses on each call
// notice the order of the intercepts
cy.intercept('/favorite-fruits', ['kiwi 🥝']) // 3rd, 4th, etc
cy.intercept('/favorite-fruits', { times: 1 }, ['grapes 🍇']) // 2nd
cy.intercept('/favorite-fruits', { times: 1 }, ['apples 🍎']) // 1st
cy.visit('/fruits.html')
cy.contains('apples 🍎')
cy.tick(30000)
cy.contains('grapes 🍇')
// after using the first two intercepts
// forever reply with "kiwi" stub
cy.tick(30000)
cy.contains('kiwi 🥝')
cy.tick(30000)
cy.contains('kiwi 🥝')
cy.tick(30000)
cy.contains('kiwi 🥝')
})
})Cypress Power
controls app clock and mocks network
Cypress Power
describe('intercept', () => {
it('returns different fruits every 30 seconds', () => {
cy.clock()
// return difference responses on each call
// notice the order of the intercepts
cy.intercept('/favorite-fruits', ['kiwi 🥝']) // 3rd, 4th, etc
cy.intercept('/favorite-fruits', { times: 1 }, ['grapes 🍇']) // 2nd
cy.intercept('/favorite-fruits', { times: 1 }, ['apples 🍎']) // 1st
cy.visit('/fruits.html')
cy.contains('apples 🍎')
cy.tick(30000)
cy.contains('grapes 🍇')
// after using the first two intercepts
// forever reply with "kiwi" stub
cy.tick(30000)
cy.contains('kiwi 🥝')
cy.tick(30000)
cy.contains('kiwi 🥝')
cy.tick(30000)
cy.contains('kiwi 🥝')
})
})controls app clock and mocks network
Cypress is a complete testing solution
- The test runner
- Built-in Electron browser
- Node.js in the config file
- Chai assertions
- Chai-jQuery & Sinon-Chai assertions
- Clock control
- Network control
- Cypress._ (Lodash), Cypress.Promise, Cypress.$, Cypress.Blob, Cypress.minimatch
How do I create a testing framework using Cypress?
You don't have to
Don't
🧑💻
Do
📚
🙇
🎓
Study (?)
$ npm i -D cypress cypress-map prettierHow I start every project...
Cypress v12
adds retriable chains of query commands.
"kiwi" is the last item 🧑🏻
get elements
take the last element
its text should be "kiwi"
🤖
it('shows the kiwi last', () => {
cy.visit('cypress/index.html')
cy.get('#items li').last().should('have.text', 'kiwi')
})get elements
take the last element
its text should be "kiwi"
🤖
it('shows the kiwi last', () => {
cy.visit('cypress/index.html')
cy.get('#items li').last().should('have.text', 'kiwi')
})Cypress v11
it('shows the kiwi last', () => {
cy.visit('cypress/index.html')
cy.get('#items li').last().should('have.text', 'kiwi')
})Cypress v12
it('shows the kiwi last', () => {
cy.visit('cypress/index.html')
cy.get('#items li')
.last()
.invoke('text')
.should('equal', 'kiwi')
})Cypress v12
it('shows 30 last', () => {
cy.visit('cypress/index.html')
cy.get('#items li')
.last()
.invoke('text')
.then(parseInt)
.should('equal', 30)
})Cypress v12
no retries
import 'cypress-map'
it('shows 30 last', () => {
cy.visit('cypress/index.html')
cy.get('#items li')
.last()
.invoke('text')
.apply(parseInt) // query from cypress-map
.should('equal', 30)
})Cypress v12
import 'cypress-map'
it('shows 30 last', () => {
cy.visit('cypress/index.html')
cy.get('#items li')
.last()
.invoke('text')
.apply(parseInt) // query from cypress-map
.should('equal', 30)
})Cypress v12
import 'cypress-map'
it('shows numbers', () => {
cy.visit('cypress/index.html')
cy.get('#items li')
.map('innerText')
.map(Number)
.should('deep.equal', [10, 20, 30])
})Cypress v12
import 'cypress-map'
it('shows numbers', () => {
cy.visit('cypress/index.html')
cy.get('#items li')
.map('innerText')
.map(Number)
.should('deep.equal', [10, 20, 30])
})Cypress v12
cypress-map
- apply
- map
- mapInvoke
- mapChain
- reduce
- tap
- ...
cypress-map
cy.table for checking the full table (or part of it)
cypress-map
Cypress query commands for v12+
Cypress tests run in the browser and Cypress can interact with the OS via its plugin file that runs in the Node process
plugins
plugins
Node.js
Process
Browser
Cypress architecture
cypress-map
cypress-each
cypress-recurse
cypress-esbuild-preprocessor
cypress-grep
cypress-watch-and-reload
cypress-data-session
Plugin Badges
Plugin written by the Cypress team
Plugin is written by a Cypress user outside the core team (most common)
Outside plugin, but reviewed by the Cypress team
Trying to prototype a feature by using a plugin first
(component testing)
cypress-real-events
import 'cypress-real-events/support'
it('over the theme switcher', () => {
cy.visit('/')
cy.get('[data-cy=add-todo]').type('text title')
cy.get('#theme-switcher').realHover()
})cypress-real-events
import 'cypress-real-events/support'
it('over the theme switcher', () => {
cy.visit('/')
cy.get('[data-cy=add-todo]').type('text title')
cy.get('#theme-switcher').realHover()
})-
Adding new things
-
Overwriting existing behavior
Cypress is just JavaScript. Anything not bolted down can be overwritten and changed.
Add New Things
it('is visible', () => {
cy.get('header').should('be.visible')
cy.get('main').should('be.visible')
cy.get('footer').should('be.visible')
})it('is visible', () => {
const selectors = ['header', 'main', 'footer']
selectors.forEach(selector => {
cy.get(selector).should('be.visible')
})
})It would be nice to create a separate test for each selector...
it.each = (items, title, cb) => {
items.forEach(item => {
it(title, function () {
return cb.call(this, item)
})
})
}const selectors = ['header', 'main', 'footer']
it.each(selectors, 'is visible', (selector) => {
cy.get(selector).should('be.visible')
})Add New Things
// create a separate test for each selector
const selectors = ['header', 'footer', '.new-todo']
it.each(selectors)('element %s is visible', (selector) => {
cy.visit('/')
cy.get(selector).should('be.visible')
})
// creates tests
// "element header is visible"
// "element footer is visible"
// "element .new-todo is visible"const data = [
// each entry is an array [selector, assertion]
['header', 'be.visible'],
['footer', 'exist']
['.new-todo', 'not.be.visible']
]
it.each(data)('element %s should %s', (selector, assertion) => {
cy.visit('/')
cy.get(selector).should(assertion)
})
// creates tests
// "element header should be.visible"
// "element footer should exist"
// "element .new-todo should not.be.visible"// repeat the same test 5 times
it.each(5)('test %K of 5', function (k) {
// note the iteration index k is passed to each test
expect(k).to.be.within(0, 4)
})Repeat the test N times
const items = [1, 2, 3, 4, 5, 6, ...]
it.each(items, 3)(...)
// tests item 1, 4, 7, ...Filter, take every Nth item
// split all items among 3 specs
// spec-a.js
it.each(items, 3, 0)(...)
// spec-b.js
it.each(items, 3, 1)(...)
// spec-c.js
it.each(items, 3, 2)(...)Split into N chunks, test one of them
// pick 2 random items from the array and create 2 tests
it.each(Cypress._.sampleSize(items, 2))(...)Pick N samples from all items
Add New Things To GUI
Re-run the test when the application files change
Unfortunately, Cypress team does not plan to help plugins implement UI elements 😢
Overwrite Existing Things
it('works', () => {
...
})
it('loads', () => {
...
})
it('saves', () => {
...
})It would be nice to run just the "it loads" test...
Overwrite Existing Things
const _it = it
const grep = Cypress.env('grep')
it = (title, cb) => {
if (title.includes(grep)) {
_it(title, cb)
} else {
_it.skip(title, cb)
}
}cypress run --env grep=loads
# or
CYPRESS_grep=loads cypress runPass plugin config via Env
require('cypress-grep')() // overwrites "it"
it('works', () => {
...
})
it('loads', {tags: '@smoke'}, () => {
...
})
it('saves', () => {
...
})$ cypress run --env grep=loads
# run all tests tagged "@smoke"
$ cypress run --env grepTags=@smoke
# run all tests NOT tagged "@smoke"
$ cypress run --env grepTags=-@smoke
# run all tests tagged "@smoke" and "@fast"
$ cypress run --env grepTags=@smoke+@fast# run the test 5 times
$ cypress run --env grep=loads,burn=5# omit filtered tests
$ cypress run --env grep=loads,grepOmitFiltered=true# omit specs without filtered tests
$ cypress run --env grep=loads,grepFilterSpecs=true# run tests without any tags
$ cypress run --env grepUntagged=true// run filtered tests 100 times
Cypress.grep('hello world', null, 100)Grep tests from DevTools
AGENDA
- Don't use plugins
- The many types of plugins
-
My (favorite) plugins
- cypress-map
- cypress-each
- cypress-watch-and-reload
- cypress-grep
- cypress-recurse
- cypress-data-session
- The end
Q: How do I click on the Next button until I get to the last page?
- get the Next button
- if it is disabled
- stop (the last page)
- else click on it
- go to step 1
import {recurse} from 'cypress-recurse'
recurse(
() => cy.get('[value=next]'),
($button) => $button.attr('disabled') === 'disabled',
{
log: 'Last page',
delay: 500,
post() {
cy.get('[value=next]').click()
},
},
)🤖
- get the Next button
- if it is disabled
- stop (the last page)
- else click on it
- go to step 1
import {recurse} from 'cypress-recurse'
recurse(
() => cy.get('[value=next]'),
($button) => $button.attr('disabled') === 'disabled',
{
log: 'Last page',
delay: 500,
post() {
cy.get('[value=next]').click()
},
},
)- Reload the page until the text appears
- Scroll the page until the text is found
- Check the list until it is sorted
- Call cy.request until it succeeds
- Call cy.task until it yields expected result
- Visual screenshot until it matches
- Type into a flaky input box
- Do X until Y...
AGENDA
- Don't use plugins
- The many types of plugins
-
My (favorite) plugins
- cypress-map
- cypress-each
- cypress-watch-and-reload
- cypress-grep
- cypress-recurse
- cypress-data-session
- The end
Data Creation Problem
function registerUser(username, password) {
...
}
function loginUser(username, password) {
...
}
it('registers user', () => {
const username = 'Test'
const password = 'MySecreT'
registerUser(username, password)
loginUser(username, password)
cy.location('pathname')
.should('equal', '/rooms')
})Data Creation Problem
function registerUser(username, password) {
...
}
function loginUser(username, password) {
...
}
it('registers user', () => {
const username = 'Test'
const password = 'MySecreT'
registerUser(username, password)
loginUser(username, password)
cy.location('pathname')
.should('equal', '/rooms')
})Run Again ...
Data Creation Problem
- Do not create the data if it exists
- Start using the existent cached data
registerUser(username, password)
loginUser(username, password)Before
cy.dataSession({
name: 'user',
setup() {
registerUser(username, password)
},
validate: true,
})
loginUser(username, password)After
Runs the test twice. The same user is re-used
Look up any stored data session from the DevTools console
- Cypress.getDataSession(name)
- Cypress.getDataSessionDetails(name)
- Cypress.clearDataSession(name)
- Cypress.clearDataSessions()
- Cypress.dataSessions(enable)
- Cypress.setDataSession(name, value)
- Cypress.formDataSessionKey(name)
cy.dataSession({
name: 'user',
setup() {
registerUser(username, password)
},
validate: true,
})
loginUser(username, password)What if the user exists in the database?
cy.dataSession({
name: 'user',
init() {
cy.task('findUser', username)
},
setup() {
registerUser(username, password)
},
validate: true,
})
loginUser(username, password)What if the user exists in the database?
Find the user and cache in memory
The user already is in the database,
and we just opened Cypress
Re-run Cypress and cached user is used
cy.dataSession({
name: 'user',
init() {
cy.task('findUser', username)
},
setup() {
registerUser(username, password)
},
validate: true,
})
loginUser(username, password)Can we "cache" the login session?
cy.dataSession({
name: 'user',
init() {
cy.task('findUser', username)
},
setup() {
registerUser(username, password)
},
validate: true,
})
cy.dataSession({
name: 'logged in',
setup() {
loginUser(username, password)
cy.getCookie('connect.sid')
},
validate: true,
recreate(cookie) {
cy.setCookie('connect.sid', cookie.value)
cy.visit('/rooms')
},
dependsOn: ['user'],
})From 4.5 seconds to 240 ms
Cypress is extendable
- cypress-map
- cypress-real-events
- cypress-each
- cypress-watch-and-reload
- cypress-grep
- cypress-recurse
- cypress-data-session
But there are lots lots lots more!
Subscribe: https://cypresstips.substack.com
100 hands-on lessons, 22 plugins, lots of videos
My Favorite Cypress Plugins
Thank you 👏
gleb.dev
@bahmutov
Gleb Bahmutov
Sr Director of Engineering at Mercari US
LambdaTest
Voices of Community
My Favorite Cypress Plugins
By Gleb Bahmutov
My Favorite Cypress Plugins
You can supercharge your end-to-end, component, and API Cypress tests using plugins. In this talk, I will show my favorite Cypress plugins, explain how they work, and how easy it is to write simple, elegant testing code. From accessing databases, receiving emails, and setting up data, to repeating commands and checking the page's accessibility - there is a Cypress plugin for everything!
