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jest-emotion
Advanced tools
Jest testing utilities for emotion
npm install --save-dev jest-emotion
The easiest way to test React components with emotion is with the snapshot serializer. (the example below is with react-test-renderer but jest-emotion also works with enzyme)
import React from 'react'
import renderer from 'react-test-renderer'
import { createSerializer } from 'jest-emotion'
import * as emotion from 'emotion'
import styled from 'react-emotion'
expect.addSnapshotSerializer(createSerializer(emotion))
test('renders with correct styles', () => {
const H1 = styled.h1`
float: left;
`
const tree = renderer.create(<H1>hello world</H1>).toJSON()
expect(tree).toMatchSnapshot()
})
Refer to the testing doc for more information about snapshot testing with emotion.
classNameReplacer
jest-emotion's snapshot serializer replaces the hashes in class names with an index so that things like whitespace changes won't break snapshots. It optionally accepts a custom class name replacer, it defaults to the below.
function classNameReplacer(className, index) {
return `emotion-${index}`
}
import * as emotion from 'emotion'
import { createSerializer } from 'jest-emotion'
expect.addSnapshotSerializer(
createSerializer(emotion, {
classNameReplacer(className, index) {
return `my-new-class-name-${index}`
}
})
)
DOMElements
jest-emotion's snapshot serializer inserts styles and replaces class names in both React and DOM elements. If you would like to disable this behavior for the latter, you can do so by setting this property to false. For example:
import * as emotion from 'emotion'
import { createSerializer } from 'jest-emotion'
// configures jest-emotion to ignore DOM elements
expect.addSnapshotSerializer(createSerializer(emotion, { DOMElements: false }))
jest-emotion also allows you to get all the css that emotion has inserted. This is meant to be an escape hatch if you don't use React or you want to build your own utilities for testing with emotion.
import * as emotion from 'emotion'
import { css } from 'emotion'
import { getStyles } from 'jest-emotion'
test('correct styles are inserted', () => {
const cls = css`
display: flex;
`
expect(getStyles(emotion)).toMatchSnapshot()
})
Thanks to Kent C. Dodds who wrote jest-glamor-react which this library is largely based on.
FAQs
Jest utilities for emotion
The npm package jest-emotion receives a total of 28,015 weekly downloads. As such, jest-emotion popularity was classified as popular.
We found that jest-emotion demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 4 open source maintainers collaborating on the project.
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