FRAMEWORK » REACT » TESTING

DOM Testing Library

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Reference:testing-library.com

Querying ​

When creating tests using DOM Testing Library, you should avoid using element.getElementsBy* and the likes. Prefer using the options given by the library.

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

First option: getByRole ​

List of roles

User actionHTMLTest
Button click<button>Submit</button>fireEvent.click(screen.getByRole('button', { name: 'Submit' }))
Insert text<label htmlFor="inputid">Message</label><input id="inputid" type="text" />fireEvent.change(screen.getByRole('textbox', { name: 'Message' }), { target: { value: 'Text to be inserted' } })
Check radio button<input id="inputid" type="radio" /><label htmlFor="inputid">Option A</label>fireEvent.click(screen.getByRole('radio', { name: 'Option A' }))
Get almost any element<input aria-label="no-label-or-placeholder" />screen.getByRole('textbox', { name: 'no-label-or-placeholder' })

Second option: getByPlaceholderText ​

When there is no <label>, aria-label, and we want to get it by placeholder.

User actionHTMLTest
Insert text<input placeholder="Name" />fireEvent.change(screen.getByPlaceholderText('Name'), { target: { value: 'Suguri' } })

Third option: getByText ​

When role is generic (like div).

User actionHTMLTest
Click a div<div onClick="doSomething()">Click me</div>fireEvent.click(screen.getByText('Click me'))

Fourth option: getByTitle ​

When role is generic and there is no text.

INFO

title is a tooltip that appears to users on hover.

User actionHTMLTest
Click a div<div onClick="doSomething()" title="Toggle menu"><i class="icon" /></div>fireEvent.click(screen.getByTitle('Toggle menu'))

Last option: getByTestId ​

When role is generic, there is no text and we don't want to insert a title.

Probably should only be used to click icons.

User actionHTMLTest
Click a div<div onClick="doSomething()" data-testid="toggle-menu"><i class="icon" /></div>fireEvent.click(screen.getByTestId('toggle-menu'))

Nesting queries ​

After getting an element, query from it instead of from screen. Reference

typescript
import { screen, within } from '@testing-library/react'

const modal = screen.getByTestId('modal');
const button = within(modal).getByRole('button');

Debug ​

Print the screen contents in HTML:

javascript
screen.debug();

Extensions ​

Jest DOM ​

Use jest-dom to extend the expect keyword and allow asserting the state of a DOM.

jsx
expect(element).toBeVisible();

React Select ​

react-select-event is a helper library to help testing react-select elements:

jsx
import selectEvent from 'react-select-event';

const selectElement = screen.getByLabelText('Please select');
await selectEvent.select(selectElement, 'Option 2');
// If the selection triggers some background request, use the `waitFor` to prevent warnings
await waitFor(() => {
  // expect() something or even keep it empty
});