README

react-hooks-testing-library

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

The problem
The solution
When to use this library
When not to use this library
Example
- useCounter.js
- useCounter.test.js
Installation
- Peer Dependencies
API
Contributors
Issues
LICENSE

The problem

You're writing an awesome custom hook and you want to test it, but as soon as you call it you see the following error:

Invariant Violation: Hooks can only be called inside the body of a function component.

You don't really want to write a component solely for testing this hook and have to work out how you were going to trigger all the various ways the hook can be updated, especially given the complexities of how you've wired the whole thing together.

The solution

The react-hooks-testing-library allows you to create a simple test harness for React hooks that handles running them within the body of a function component, as well as providing various useful utility functions for updating the inputs and retrieving the outputs of your amazing custom hook. This library aims to provide a testing experience as close as possible to natively using your hook from within a real component.

Using this library, you do not have to concern yourself with how to construct, render or interact with the react component in order to test your hook. You can just use the hook directly and assert the results.

When to use this library

You're writing a library with one or more custom hooks that are not directly tied to a component
You have a complex hook that is difficult to test through component interactions

When not to use this library

Your hook is defined alongside a component and is only used there
Your hook is easy to test by just testing the components using it

Example

`useCounter.js`

import { useState, useCallback } from 'react'

function useCounter() {
  const [count, setCount] = useState(0)

  const increment = useCallback(() => setCount((x) => x + 1), [])

  return { count, increment }
}

export default useCounter

`useCounter.test.js`

import { renderHook, act } from '@testing-library/react-hooks'
import useCounter from './useCounter'

test('should increment counter', () => {
  const { result } = renderHook(() => useCounter())

  act(() => {
    result.current.increment()
  })

  expect(result.current.count).toBe(1)
})

More advanced usage can be found in the documentation.

Installation

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

Peer Dependencies

react-hooks-testing-library does not come bundled with a version of react to allow you to install the specific version you want to test against. It also does not come installed with a specific renderer, we currently support react-test-renderer and react-dom. You only need to install one of them, however, if you do have both installed, we will use react-test-renderer as the default. For more information see the installation docs. Generally, the installed versions for react and the selected renderer should have matching versions:

npm install react@^16.9.0
npm install --save-dev react-test-renderer@^16.9.0

NOTE: The minimum supported version of react, react-test-renderer and react-dom is ^16.9.0.

API

See the API reference.

Contributors

Thanks goes to these wonderful people (emoji key):

_{Michael Peyper} 💻 📖 🤔 🚇 🚧 💬 ⚠️	_otofu-square 💻	_{Patrick P. Henley} 🤔 👀	_{Matheus Marques} 💻	_{Dhruv Patel} 🐛 👀	_{Nathaniel Tucker} 🐛 👀	_{Sergei Grishchenko} 💻 📖 🤔
_{Josep M Sobrepere} 📖	_{Marcel Tinner} 📖	_{Daniel K.} 🐛 💻	_{Vince Malone} 💻	_{Sebastian Weber} 📝	_{Christian Gill} 📖	_{JavaScript Joe} ✅
_{Sarah Dayan} 📦	_{Roman Gusev} 📖	_{Adam Seckel} 💻	_{keiya sasaki} ⚠️	_{Hu Chen} 💻 📖 💡	_Josh 📖 💬 💻 🤔 🚧 ⚠️	_{Na'aman Hirschfeld} 💻
_{Braydon Hall} 💻	_{Jacob M-G Evans} 💻 ⚠️	_{Tiger Abrodi} 💻 ⚠️	_{Amr A.Mohammed} 💻 ⚠️	_{Juhana Jauhiainen} 💻	_{Jens Meindertsma} 💻 ⚠️	_{Marco Moretti} 🚇
_{Martin V.} 📖	_Erozak 📖	_{Nick McCurdy} 🚧	_Arya 📖	_numb86 📖	_{Alex Young} 🚧	_{Ben Lambert} 📖
_{David Cho-Lerat} 📖	_{Evan Harmon} 📖	_{Jason Brown} 📖	_{KahWee Teng} 📖	_{Leonid Shagabutdinov} 📖	_{Levi Butcher} 📖	_{Michele Settepani} 📖
_Sam 📖	_{Tanay Pratap} 📖	_{Tom Rees-Herdman} 📖	_iqbal125 📖	_{cliffzhaobupt} 🚧	_{Jon Koops} 💻	_{Jonathan Peyper} 👀 💻