@testing-library/react (original) (raw)

React Testing Library

goat

Simple and complete React DOM testing utilities that encourage good testing practices.

Read The Docs |Edit the docs

Build Status Code Coverage version downloads MIT License All Contributors PRs Welcome Code of Conduct Discord

Watch on GitHub Star on GitHub Tweet

TestingJavaScript.com Learn the smart, efficient way to test any JavaScript application.

Table of Contents

The problem

You want to write maintainable tests for your React components. As a part of this goal, you want your tests to avoid including implementation details of your components and rather focus on making your tests give you the confidence for which they are intended. As part of this, you want your testbase to be maintainable in the long run so refactors of your components (changes to implementation but not functionality) don't break your tests and slow you and your team down.

The solution

The React Testing Library is a very lightweight solution for testing React components. It provides light utility functions on top of react-dom andreact-dom/test-utils, in a way that encourages better testing practices. Its primary guiding principle is:

The more your tests resemble the way your software is used, the more confidence they can give you.

Installation

This module is distributed via npm which is bundled with node and should be installed as one of your project's devDependencies.
Starting from RTL version 16, you'll also need to install@testing-library/dom:

npm install --save-dev @testing-library/react @testing-library/dom

or

for installation via yarn

yarn add --dev @testing-library/react @testing-library/dom

This library has peerDependencies listings for react, react-dom and starting from RTL version 16 also @testing-library/dom.

React Testing Library versions 13+ require React v18. If your project uses an older version of React, be sure to install version 12:

npm install --save-dev @testing-library/react@12


yarn add --dev @testing-library/react@12

You may also be interested in installing @testing-library/jest-dom so you can use the custom jest matchers.

Docs

Suppressing unnecessary warnings on React DOM 16.8

There is a known compatibility issue with React DOM 16.8 where you will see the following warning:

Warning: An update to ComponentName inside a test was not wrapped in act(...).

If you cannot upgrade to React DOM 16.9, you may suppress the warnings by adding the following snippet to your test configuration (learn more):

// this is just a little hack to silence a warning that we'll get until we // upgrade to 16.9. See also: https://github.com/facebook/react/pull/14853 const originalError = console.error beforeAll(() => { console.error = (...args) => { if (/Warning.*not wrapped in act/.test(args[0])) { return } originalError.call(console, ...args) } })

afterAll(() => { console.error = originalError })

Examples

Basic Example

// hidden-message.js import * as React from 'react'

// NOTE: React Testing Library works well with React Hooks and classes. // Your tests will be the same regardless of how you write your components. function HiddenMessage({children}) { const [showMessage, setShowMessage] = React.useState(false) return (

Show Message <input id="toggle" type="checkbox" onChange={e => setShowMessage(e.target.checked)} checked={showMessage} /> {showMessage ? children : null}
) }

export default HiddenMessage

// tests/hidden-message.js // these imports are something you'd normally configure Jest to import for you // automatically. Learn more in the setup docs: https://testing-library.com/docs/react-testing-library/setup#cleanup import '@testing-library/jest-dom' // NOTE: jest-dom adds handy assertions to Jest and is recommended, but not required

import * as React from 'react' import {render, fireEvent, screen} from '@testing-library/react' import HiddenMessage from '../hidden-message'

test('shows the children when the checkbox is checked', () => { const testMessage = 'Test Message' render({testMessage})

// query* functions will return the element or null if it cannot be found // get* functions will return the element or throw an error if it cannot be found expect(screen.queryByText(testMessage)).toBeNull()

// the queries can accept a regex to make your selectors more resilient to content tweaks and changes. fireEvent.click(screen.getByLabelText(/show/i))

// .toBeInTheDocument() is an assertion that comes from jest-dom // otherwise you could use .toBeDefined() expect(screen.getByText(testMessage)).toBeInTheDocument() })

Complex Example

// login.js import * as React from 'react'

function Login() { const [state, setState] = React.useReducer((s, a) => ({...s, ...a}), { resolved: false, loading: false, error: null, })

function handleSubmit(event) { event.preventDefault() const {usernameInput, passwordInput} = event.target.elements

setState({loading: true, resolved: false, error: null})

window
  .fetch('/api/login', {
    method: 'POST',
    headers: {'Content-Type': 'application/json'},
    body: JSON.stringify({
      username: usernameInput.value,
      password: passwordInput.value,
    }),
  })
  .then(r => r.json().then(data => (r.ok ? data : Promise.reject(data))))
  .then(
    user => {
      setState({loading: false, resolved: true, error: null})
      window.localStorage.setItem('token', user.token)
    },
    error => {
      setState({loading: false, resolved: false, error: error.message})
    },
  )

}

return (

Username
Password
Submit{state.loading ? '...' : null} {state.error ?
{state.error}
: null} {state.resolved ? (
Congrats! You're signed in!
) : null}
) }

export default Login

// tests/login.js // again, these first two imports are something you'd normally handle in // your testing framework configuration rather than importing them in every file. import '@testing-library/jest-dom' import * as React from 'react' // import API mocking utilities from Mock Service Worker. import {rest} from 'msw' import {setupServer} from 'msw/node' // import testing utilities import {render, fireEvent, screen} from '@testing-library/react' import Login from '../login'

const fakeUserResponse = {token: 'fake_user_token'} const server = setupServer( rest.post('/api/login', (req, res, ctx) => { return res(ctx.json(fakeUserResponse)) }), )

beforeAll(() => server.listen()) afterEach(() => { server.resetHandlers() window.localStorage.removeItem('token') }) afterAll(() => server.close())

test('allows the user to login successfully', async () => { render()

// fill out the form fireEvent.change(screen.getByLabelText(/username/i), { target: {value: 'chuck'}, }) fireEvent.change(screen.getByLabelText(/password/i), { target: {value: 'norris'}, })

fireEvent.click(screen.getByText(/submit/i))

// just like a manual tester, we'll instruct our test to wait for the alert // to show up before continuing with our assertions. const alert = await screen.findByRole('alert')

// .toHaveTextContent() comes from jest-dom's assertions // otherwise you could use expect(alert.textContent).toMatch(/congrats/i) // but jest-dom will give you better error messages which is why it's recommended expect(alert).toHaveTextContent(/congrats/i) expect(window.localStorage.getItem('token')).toEqual(fakeUserResponse.token) })

test('handles server exceptions', async () => { // mock the server error response for this test suite only. server.use( rest.post('/api/login', (req, res, ctx) => { return res(ctx.status(500), ctx.json({message: 'Internal server error'})) }), )

render()

// fill out the form fireEvent.change(screen.getByLabelText(/username/i), { target: {value: 'chuck'}, }) fireEvent.change(screen.getByLabelText(/password/i), { target: {value: 'norris'}, })

fireEvent.click(screen.getByText(/submit/i))

// wait for the error message const alert = await screen.findByRole('alert')

expect(alert).toHaveTextContent(/internal server error/i) expect(window.localStorage.getItem('token')).toBeNull() })

We recommend using Mock Service Worker library to declaratively mock API communication in your tests instead of stubbingwindow.fetch, or relying on third-party adapters.

More Examples

We're in the process of moving examples to thedocs site

You'll find runnable examples of testing with different libraries inthe react-testing-library-examples codesandbox. Some included are:

Hooks

If you are interested in testing a custom hook, check out React Hooks Testing Library.

NOTE: it is not recommended to test single-use custom hooks in isolation from the components where it's being used. It's better to test the component that's using the hook rather than the hook itself. The React Hooks Testing Libraryis intended to be used for reusable hooks/libraries.

Guiding Principles

The more your tests resemble the way your software is used, the more confidence they can give you.

We try to only expose methods and utilities that encourage you to write tests that closely resemble how your React components are used.

Utilities are included in this project based on the following guiding principles:

  1. If it relates to rendering components, it deals with DOM nodes rather than component instances, nor should it encourage dealing with component instances.
  2. It should be generally useful for testing individual React components or full React applications. While this library is focused on react-dom, utilities could be included even if they don't directly relate toreact-dom.
  3. Utility implementations and APIs should be simple and flexible.

Most importantly, we want React Testing Library to be pretty light-weight, simple, and easy to understand.

Docs

Read The Docs |Edit the docs

Issues

Looking to contribute? Look for the Good First Issue label.

πŸ› Bugs

Please file an issue for bugs, missing documentation, or unexpected behavior.

See Bugs

πŸ’‘ Feature Requests

Please file an issue to suggest new features. Vote on feature requests by adding a πŸ‘. This helps maintainers prioritize what to work on.

See Feature Requests

❓ Questions

For questions related to using the library, please visit a support community instead of filing an issue on GitHub.

Contributors

Thanks goes to these people (emoji key):

Kent C. Dodds Kent C. DoddsπŸ’» πŸ“– πŸš‡ ⚠️ Ryan Castner Ryan CastnerπŸ“– Daniel Sandiego Daniel SandiegoπŸ’» PaweΕ‚ MikoΕ‚ajczyk PaweΕ‚ MikoΕ‚ajczykπŸ’» Alejandro ÑÑñez Ortiz Alejandro ÑÑñez OrtizπŸ“– Matt Parrish Matt ParrishπŸ› πŸ’» πŸ“– ⚠️ Justin Hall Justin HallπŸ“¦
Anto Aravinth Anto AravinthπŸ’» ⚠️ πŸ“– Jonah Moses Jonah MosesπŸ“– Łukasz Gandecki Łukasz GandeckiπŸ’» ⚠️ πŸ“– Ivan Babak Ivan BabakπŸ› πŸ€” Jesse Day Jesse DayπŸ’» Ernesto GarcΓ­a Ernesto GarcΓ­aπŸ’¬ πŸ’» πŸ“– Josef Maxx Blake Josef Maxx BlakeπŸ’» πŸ“– ⚠️
Michal Baranowski Michal BaranowskiπŸ“ βœ… Arthur Puthin Arthur PuthinπŸ“– Thomas Chia Thomas ChiaπŸ’» πŸ“– Thiago Galvani Thiago GalvaniπŸ“– Christian Christian⚠️ Alex Krolick Alex KrolickπŸ’¬ πŸ“– πŸ’‘ πŸ€” Johann Hubert Sonntagbauer Johann Hubert SonntagbauerπŸ’» πŸ“– ⚠️
Maddi Joyce Maddi JoyceπŸ’» Ryan Vice Ryan ViceπŸ“– Ian Wilson Ian WilsonπŸ“ βœ… Daniel DanielπŸ› πŸ’» Giorgio Polvara Giorgio PolvaraπŸ› πŸ€” John Gozde John GozdeπŸ’» Sam Horton Sam HortonπŸ“– πŸ’‘ πŸ€”
Richard Kotze (mobile) Richard Kotze (mobile)πŸ“– Brahian E. Soto Mercedes Brahian E. Soto MercedesπŸ“– Benoit de La Forest Benoit de La ForestπŸ“– Salah SalahπŸ’» ⚠️ Adam Gordon Adam GordonπŸ› πŸ’» Matija MarohniΔ‡ Matija MarohniΔ‡πŸ“– Justice Mba Justice MbaπŸ“–
Mark Pollmann Mark PollmannπŸ“– Ehtesham Kafeel Ehtesham KafeelπŸ’» πŸ“– Julio PavΓ³n Julio PavΓ³nπŸ’» Duncan L Duncan LπŸ“– πŸ’‘ Tiago Almeida Tiago AlmeidaπŸ“– Robert Smith Robert SmithπŸ› Zach Green Zach GreenπŸ“–
dadamssg dadamssgπŸ“– Yazan Aabed Yazan AabedπŸ“ Tim TimπŸ› πŸ’» πŸ“– ⚠️ Divyanshu Maithani Divyanshu Maithaniβœ… πŸ“Ή Deepak Grover Deepak Groverβœ… πŸ“Ή Eyal Cohen Eyal CohenπŸ“– Peter Makowski Peter MakowskiπŸ“–
Michiel Nuyts Michiel NuytsπŸ“– Joe Ng'ethe Joe Ng'etheπŸ’» πŸ“– Kate KateπŸ“– Sean SeanπŸ“– James Long James LongπŸ€” πŸ“¦ Herb Hagely Herb HagelyπŸ’‘ Alex Wendte Alex WendteπŸ’‘
Monica Powell Monica PowellπŸ“– Vitaly Sivkov Vitaly SivkovπŸ’» Weyert de Boer Weyert de BoerπŸ€” πŸ‘€ 🎨 EstebanMarin EstebanMarinπŸ“– Victor Martins Victor MartinsπŸ“– Royston Shufflebotham Royston ShufflebothamπŸ› πŸ“– πŸ’‘ chrbala chrbalaπŸ’»
Donavon West Donavon WestπŸ’» πŸ“– πŸ€” ⚠️ Richard Maisano Richard MaisanoπŸ’» Marco Biedermann Marco BiedermannπŸ’» 🚧 ⚠️ Alex Zherdev Alex ZherdevπŸ› πŸ’» AndrΓ© Matulionis dos Santos AndrΓ© Matulionis dos SantosπŸ’» πŸ’‘ ⚠️ Daniel K. Daniel K.πŸ› πŸ’» πŸ€” ⚠️ πŸ‘€ mohamedmagdy17593 mohamedmagdy17593πŸ’»
Loren ☺️ Loren β˜ΊοΈπŸ“– MarkFalconbridge MarkFalconbridgeπŸ› πŸ’» Vinicius ViniciusπŸ“– πŸ’‘ Peter Schyma Peter SchymaπŸ’» Ian Schmitz Ian SchmitzπŸ“– Joel Marcotte Joel MarcotteπŸ› ⚠️ πŸ’» Alejandro Dustet Alejandro DustetπŸ›
Brandon Carroll Brandon CarrollπŸ“– Lucas Machado Lucas MachadoπŸ“– Pascal Duez Pascal DuezπŸ“¦ Minh Nguyen Minh NguyenπŸ’» LiaoJimmy LiaoJimmyπŸ“– Sunil Pai Sunil PaiπŸ’» ⚠️ Dan Abramov Dan AbramovπŸ‘€
Christian Murphy Christian MurphyπŸš‡ Ivakhnenko Dmitry Ivakhnenko DmitryπŸ’» James George James GeorgeπŸ“– JoΓ£o Fernandes JoΓ£o FernandesπŸ“– Alejandro Perea Alejandro PereaπŸ‘€ Nick McCurdy Nick McCurdyπŸ‘€ πŸ’¬ πŸš‡ Sebastian Silbermann Sebastian SilbermannπŸ‘€
AdriΓ  Fontcuberta AdriΓ  FontcubertaπŸ‘€ πŸ“– John Reilly John ReillyπŸ‘€ MichaΓ«l De Boey MichaΓ«l De BoeyπŸ‘€ πŸ’» Tim Yates Tim YatesπŸ‘€ Brian Donovan Brian DonovanπŸ’» Noam Gabriel Jacobson Noam Gabriel JacobsonπŸ“– Ronald van der Kooij Ronald van der Kooij⚠️ πŸ’»
Aayush Rajvanshi Aayush RajvanshiπŸ“– Ely Alamillo Ely AlamilloπŸ’» ⚠️ Daniel Afonso Daniel AfonsoπŸ’» ⚠️ Laurens Bosscher Laurens BosscherπŸ’» Sakito Mukai Sakito MukaiπŸ“– TΓΌrker Teke TΓΌrker TekeπŸ“– Zach Brogan Zach BroganπŸ’» ⚠️
Ryota Murakami Ryota MurakamiπŸ“– Michael Hottman Michael HottmanπŸ€” Steven Fitzpatrick Steven FitzpatrickπŸ› Juan Je GarcΓ­a Juan Je GarcΓ­aπŸ“– Championrunner ChampionrunnerπŸ“– Sam Tsai Sam TsaiπŸ’» ⚠️ πŸ“– Christian Rackerseder Christian RackersederπŸ’»
Andrei Picus Andrei PicusπŸ› πŸ‘€ Artem Zakharchenko Artem ZakharchenkoπŸ“– Michael MichaelπŸ“– Braden Lee Braden LeeπŸ“– Kamran Ayub Kamran AyubπŸ’» ⚠️ Matan Borenkraout Matan BorenkraoutπŸ’» Ryan Bigg Ryan Bigg🚧
Anton Halim Anton HalimπŸ“– Artem Malko Artem MalkoπŸ’» Gerrit Alex Gerrit AlexπŸ’» Karthick Raja Karthick RajaπŸ’» Abdelrahman Ashraf Abdelrahman AshrafπŸ’» Lidor Avitan Lidor AvitanπŸ“– Jordan Harband Jordan HarbandπŸ‘€ πŸ€”
Marco Moretti Marco MorettiπŸ’» sanchit121 sanchit121πŸ› πŸ’» Solufa SolufaπŸ› πŸ’» Ari PerkkiΓΆ Ari Perkkiâ⚠️ Johannes Ewald Johannes EwaldπŸ’» Angus J. Pope Angus J. PopeπŸ“– Dominik Lesch Dominik LeschπŸ“–
Marcos GΓ³mez Marcos GΓ³mezπŸ“– Akash Shyam Akash ShyamπŸ› Fabian Meumertzheim Fabian MeumertzheimπŸ’» πŸ› Sebastian Malton Sebastian MaltonπŸ› πŸ’» Martin BΓΆttcher Martin BΓΆttcherπŸ’» Dominik Dorfmeister Dominik DorfmeisterπŸ’» Stephen Sauceda Stephen SaucedaπŸ“–
Colin Diesh Colin DieshπŸ“– Yusuke Iinuma Yusuke IinumaπŸ’» Jeff Way Jeff WayπŸ’» Bernardo Belchior Bernardo BelchiorπŸ’» πŸ“–

This project follows the all-contributors specification. Contributions of any kind welcome!

LICENSE

MIT