jest-component-snapshot 📸

Component snapshot testing made easy.

Install ⚙️

yarn add -D jest-component-snapshot puppeteer

Usage 🤖

The recommended way to use this library is by adding the following to your Jest config:

{
  "globalSetup": "jest-component-snapshot/setup",
  "globalTeardown": "jest-component-snapshot/teardown",
  "setupFilesAfterEnv": ["jest-component-snapshot/extend-expect"]
}

This config is optional - the globalSetup and globalTeardown functions ensure that the same instance of Puppeteer is shared between tests to improve performance. If you do not set these options then a new instance of Puppeteer will be launched for each test.

If you cannot configure setupFilesAfterEnv (such as in create-react-app), you can manually extend Jest in your test files using:

import { extendExpect } from 'jest-component-snapshot'

extendExpect()

Image snapshot tests

Creates an image snapshot from a component using jest-image-snapshot. All of the same options are supported.

test('image snapshot from HTML string', () => {
  expect('<h1>Hello world</h1>').toMatchImageSnapshot()
})

test('image snapshot from DOM element', () => {
  const headingElement = document.createElement('h1')
  headingElement.innerHtml = 'Hello world'

  expect(headingElement).toMatchImageSnapshot()
})

test('image snapshot from React element', () => {
  expect(<h1>Hello world</h1>).toMatchImageSnapshot()
})

A11y snapshot tests

Uses Puppeteer to create an accessibility tree snapshot. The snapshot is converted to YAML for readability and empty properties and generic containers are removed.

test('a11y snapshot from HTML string', () => {
  expect('<h1>Hello world</h1>').toMatchA11ySnapshot()
})

test('a11y snapshot from DOM element', () => {
  const headingElement = document.createElement('h1')
  headingElement.innerHtml = 'Hello world'

  expect(headingElement).toMatchA11ySnapshot()
})

test('a11y snapshot from React element', () => {
  expect(<h1>Hello world</h1>).toMatchA11ySnapshot()
})

DOM snapshot tests

Snapshots formatted HTML for the given component.

test('DOM snapshot from HTML string', () => {
  expect('<h1>Hello world</h1>').toMatchDomSnapshot()
})

test('DOM snapshot from DOM element', () => {
  const headingElement = document.createElement('h1')
  headingElement.innerHtml = 'Hello world'

  expect(headingElement).toMatchDomSnapshot()
})

test('DOM snapshot from React element', () => {
  expect(<h1>Hello world</h1>).toMatchDomSnapshot()
})

mmmurray / jest-component-snapshot Goto Github PK