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react-testing-library

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

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React Testing Library

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

**Read The Docs** | Edit the docs


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

Table of Contents

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.

This solution

The

React Testing Library

is a very lightweight solution for testing React components. It provides light utility functions on top of

react-dom

and

react-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

:

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

or

for installation via yarn

yarn add --dev @testing-library/react

This library has

peerDependencies

listings for

react

and

react-dom

.

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: 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 React from 'react' // NOTE: React Testing Library works with React Hooks \_and\_ classes just as well // and your tests will be the same however you write your components. function HiddenMessage({children}) { const [showMessage, setShowMessage] = React.useState(false) return ( 
<label htmlfor="toggle">Show Message</label><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 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(<hiddenmessage>{testMessage}</hiddenmessage>) // 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 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( user =\> { setState({loading: false, resolved: true, error: null}) window.localStorage.setItem('token', user.token) }, error =\> { setState({loading: false, resolved: false, error: error.message}) }, ) } return ( 
<form onsubmit="{handleSubmit}">
        <div>
          <label htmlfor="usernameInput">Username</label>
          <input id="usernameInput">
        </div>
        <div>
          <label htmlfor="passwordInput">Password</label>
          <input id="passwordInput" type="password">
        </div>
        <button type="submit">Submit{state.loading ? '...' : null}</button>
      </form> {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 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 server = setupServer( rest.post('/api/login', (req, res, ctx) =\> { return res(ctx.json({token: 'fake\_user\_token'})) }), ) beforeAll(() =\> server.listen()) afterEach(() =\> { server.resetHandlers() window.localStorage.removeItem('token') }) afterAll(() =\> server.close()) test('allows the user to login successfully', async () =\> { render(<login></login>) // 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('/', (req, res, ctx) =\> { return res(ctx.status(500), ctx.json({message: 'Internal server error'})) }), ) render(<login></login>) // 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 stubbing

window.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 in[the

react-testing-library-examples

codesandbox](https://codesandbox.io/s/github/kentcdodds/react-testing-library-examples). Some included are:

You can also find React Testing Library examples atreact-testing-examples.com.

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 Library

is 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 to
    react-dom
    .
  3. Utility implementations and APIs should be simple and flexible.

At the end of the day, what we want is for this library to be pretty light-weight, simple, and understandable.

Docs

Read The Docs |Edit the docs

Issues

Looking to contribute? Look for the Good First Issuelabel.

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

πŸ’» πŸ“– πŸš‡ ⚠️ |
Ryan Castner

πŸ“– |
Daniel Sandiego

πŸ’» |
PaweΕ‚ MikoΕ‚ajczyk

πŸ’» |
Alejandro ÑÑñez Ortiz

πŸ“– |
Matt Parrish

πŸ› πŸ’» πŸ“– ⚠️ |
Justin Hall

πŸ“¦ | |
Anto Aravinth

πŸ’» ⚠️ πŸ“– |
Jonah Moses

πŸ“– |
Łukasz Gandecki

πŸ’» ⚠️ πŸ“– |
Ivan Babak

πŸ› πŸ€” |
Jesse Day

πŸ’» |
Ernesto GarcΓ­a

πŸ’¬ πŸ’» πŸ“– |
Josef Maxx Blake

πŸ’» πŸ“– ⚠️ | |
Michal Baranowski

πŸ“ βœ… |
Arthur Puthin

πŸ“– |
Thomas Chia

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Thiago Galvani

πŸ“– |
Christian

⚠️ |
Alex Krolick

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Johann Hubert Sonntagbauer

πŸ’» πŸ“– ⚠️ | |
Maddi Joyce

πŸ’» |
Ryan Vice

πŸ“– |
Ian Wilson

πŸ“ βœ… |
Daniel

πŸ› πŸ’» |
Giorgio Polvara

πŸ› πŸ€” |
John Gozde

πŸ’» |
Sam Horton

πŸ“– πŸ’‘ πŸ€” | |
Richard Kotze (mobile)

πŸ“– |
Brahian E. Soto Mercedes

πŸ“– |
Benoit de La Forest

πŸ“– |
Salah

πŸ’» ⚠️ |
Adam Gordon

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Matija Marohnić

πŸ“– |
Justice Mba

πŸ“– | |
Mark Pollmann

πŸ“– |
Ehtesham Kafeel

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Julio PavΓ³n

πŸ’» |
Duncan L

πŸ“– πŸ’‘ |
Tiago Almeida

πŸ“– |
Robert Smith

πŸ› |
Zach Green

πŸ“– | |
dadamssg

πŸ“– |
Yazan Aabed

πŸ“ |
Tim

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Divyanshu Maithani

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Deepak Grover

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Eyal Cohen

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Peter Makowski

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Michiel Nuyts

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Joe Ng'ethe

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Kate

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Sean

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James Long

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Herb Hagely

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Alex Wendte

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Monica Powell

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Vitaly Sivkov

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Weyert de Boer

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EstebanMarin

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Victor Martins

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Royston Shufflebotham

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chrbala

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Donavon West

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Richard Maisano

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Marco Biedermann

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Alex Zherdev

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AndrΓ© Matulionis dos Santos

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Daniel K.

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mohamedmagdy17593

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Loren ☺️

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MarkFalconbridge

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Vinicius

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Peter Schyma

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Ian Schmitz

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Joel Marcotte

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Alejandro Dustet

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Brandon Carroll

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Pascal Duez

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Minh Nguyen

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LiaoJimmy

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Dan Abramov

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Christian Murphy

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Nick McCurdy

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Tim Yates

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Brian Donovan

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Noam Gabriel Jacobson

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Ronald van der Kooij

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Aayush Rajvanshi

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Ely Alamillo

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Daniel Afonso

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Laurens Bosscher

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Sakito Mukai

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TΓΌrker Teke

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Zach Brogan

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Ryota Murakami

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Michael Hottman

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Steven Fitzpatrick

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Sam Tsai

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Christian Rackerseder

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Artem Zakharchenko

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Michael

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Braden Lee

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Kamran Ayub

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Matan Borenkraout

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

LICENSE

MIT

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