API

React Testing Library re-exports everything from DOM Testing Library as well as these methods:


render

function render(
ui: React.ReactElement<any>,
options?: {
/* You won't often use this, expand below for docs on options */
}
): RenderResult

Render into a container which is appended to document.body.

import { render } from '@testing-library/react'
render(<div />)
import { render } from '@testing-library/react'
import '@testing-library/jest-dom/extend-expect'
test('renders a message', () => {
const { container, getByText } = render(<Greeting />)
expect(getByText('Hello, world!')).toBeInTheDocument()
expect(container.firstChild).toMatchInlineSnapshot(`
<h1>Hello, World!</h1>
`)
})

render Options

You won't often need to specify options, but if you ever do, here are the available options which you could provide as a second argument to render.

container

By default, React Testing Library will create a div and append that div to the document.body and this is where your React component will be rendered. If you provide your own HTMLElement container via this option, it will not be appended to the document.body automatically.

For example: If you are unit testing a tablebody element, it cannot be a child of a div. In this case, you can specify a table as the render container.

const table = document.createElement('table')
const { container } = render(<TableBody {...props} />, {
container: document.body.appendChild(table),
})

baseElement

If the container is specified, then this defaults to that, otherwise this defaults to document.body. This is used as the base element for the queries as well as what is printed when you use debug().

hydrate

If hydrate is set to true, then it will render with ReactDOM.hydrate. This may be useful if you are using server-side rendering and use ReactDOM.hydrate to mount your components.

wrapper

Pass a React Component as the wrapper option to have it rendered around the inner element. This is most useful for creating reusable custom render functions for common data providers. See setup for examples.

queries

Queries to bind. Overrides the default set from DOM Testing Library unless merged.

// Example, a function to traverse table contents
import * as tableQueries from 'my-table-query-libary'
import { queries } from '@testing-library/react'
const { getByRowColumn, getByText } = render(<MyTable />, {
queries: { ...queries, ...tableQueries },
})

See helpers for guidance on using utility functions to create custom queries.

Custom queries can also be added globally by following the custom render guide.

render Result

The render method returns an object that has a few properties:

...queries

The most important feature of render is that the queries from DOM Testing Library are automatically returned with their first argument bound to the baseElement, which defaults to document.body.

See Queries for a complete list.

Example

const { getByLabelText, queryAllByTestId } = render(<Component />)

container

The containing DOM node of your rendered React Element (rendered using ReactDOM.render). It's a div. This is a regular DOM node, so you can call container.querySelector etc. to inspect the children.

Tip: To get the root element of your rendered element, use container.firstChild.

NOTE: When that root element is a React Fragment, container.firstChild will only get the first child of that Fragment, not the Fragment itself.

๐Ÿšจ If you find yourself using container to query for rendered elements then you should reconsider! The other queries are designed to be more resilient to changes that will be made to the component you're testing. Avoid using container to query for elements!

baseElement

The containing DOM node where your React Element is rendered in the container. If you don't specify the baseElement in the options of render, it will default to document.body.

This is useful when the component you want to test renders something outside the container div, e.g. when you want to snapshot test your portal component which renders its HTML directly in the body.

Note: the queries returned by the render looks into baseElement, so you can use queries to test your portal component without the baseElement.

debug

NOTE: It's recommended to use screen.debug instead.

This method is a shortcut for console.log(prettyDOM(baseElement)).

import React from 'react'
import { render } from '@testing-library/react'
const HelloWorld = () => <h1>Hello World</h1>
const { debug } = render(<HelloWorld />)
debug()
// <div>
// <h1>Hello World</h1>
// </div>
// you can also pass an element: debug(getByTestId('messages'))
// and you can pass all the same arguments to debug as you can
// to prettyDOM:
// const maxLengthToPrint = 10000
// debug(getByTestId('messages'), maxLengthToPrint, {highlight: false})

This is a simple wrapper around prettyDOM which is also exposed and comes from DOM Testing Library.

rerender

It'd probably be better if you test the component that's doing the prop updating to ensure that the props are being updated correctly (see the Guiding Principles section). That said, if you'd prefer to update the props of a rendered component in your test, this function can be used to update props of the rendered component.

import { render } from '@testing-library/react'
const { rerender } = render(<NumberDisplay number={1} />)
// re-render the same component with different props
rerender(<NumberDisplay number={2} />)

See the examples page

unmount

This will cause the rendered component to be unmounted. This is useful for testing what happens when your component is removed from the page (like testing that you don't leave event handlers hanging around causing memory leaks).

This method is a pretty small abstraction over ReactDOM.unmountComponentAtNode

import { render } from '@testing-library/react'
const { container, unmount } = render(<Login />)
unmount()
// your component has been unmounted and now: container.innerHTML === ''

asFragment

Returns a DocumentFragment of your rendered component. This can be useful if you need to avoid live bindings and see how your component reacts to events.

import React, { useState } from 'react'
import { render, fireEvent } from '@testing-library/react'
const TestComponent = () => {
const [count, setCounter] = useState(0)
return (
<button onClick={() => setCounter(count => count + 1)}>
Click to increase: {count}
</button>
)
}
const { getByText, asFragment } = render(<TestComponent />)
const firstRender = asFragment()
fireEvent.click(getByText(/Click to increase/))
// This will snapshot only the difference between the first render, and the
// state of the DOM after the click event.
// See https://github.com/jest-community/snapshot-diff
expect(firstRender).toMatchDiffSnapshot(asFragment())

cleanup

Unmounts React trees that were mounted with render.

Please note that this is done automatically if the testing framework you're using supports the afterEach global and it is injected to your testing environment (like mocha, Jest, and Jasmine). If not, you will need to do manual cleanups after each test.

For example, if you're using the ava testing framework, then you would need to use the test.afterEach hook like so:

import { cleanup, render } from '@testing-library/react'
import test from 'ava'
test.afterEach(cleanup)
test('renders into document', () => {
render(<div />)
// ...
})
// ... more tests ...

Failing to call cleanup when you've called render could result in a memory leak and tests which are not "idempotent" (which can lead to difficult to debug errors in your tests).


act

This is a light wrapper around the react-dom/test-utils act function. All it does is forward all arguments to the act function if your version of react supports act. It is recommended to use the import from @testing-library/react over react-dom/test-utils for consistency reasons.

Last updated on by Matan Borenkraout