jest: ReferenceError: KeyframeEffect is not defined

Question

I'm recently learning how to write component tests with jest and the react testing library.

I have an animation in useLayoutEffect, the code works fine on the browser but has error in jest, the code and error message are as follows

Progress/index.tsx

import React, { useRef, useState, useLayoutEffect, useEffect } from "react"
import { useCarousel, useCarouselDispatch } from "../../store/AppContext"
import { ECarouselActionType } from '../../store/types'
import "./styles.css"

export default function Progress( { pid }: { pid: number}) {
  const { progressId } = useCarousel()
  const dispatch = useCarouselDispatch()
  const inner = useRef<HTMLDivElement>(null)
  useLayoutEffect(()=>{
    if (pid === progressId) {
      const keyframes = new KeyframeEffect(
        inner.current, 
        [
          { transform: 'scaleX(0%)', transformOrigin: 'left center' }, 
          { transform: 'scaleX(100%)', transformOrigin: 'left center' }
        ],
        { duration: 3000, fill: 'forwards' }
      );
      const anim = new Animation(keyframes, document.timeline);
      anim.play()
      const finish = anim.finished
      finish.then(() => {
        dispatch({
          type: ECarouselActionType.SET_MOVE
        })
      })
    }
  }, [progressId])
  return (
    <div className="Progress">
      <div className="progress-wrap">
        <div className="progress-bar progress-outer">
          <div 
            className="progress-bar progress-inner" 
            ref={inner} 
            style={{ background: pid === progressId ? '#fff' : '#9aa0a6'}}
          >
          </div>
        </div>
      </div>
    </div>
  )
}

App.test.tsx // Not the actual test case, just to see the test running process

/**
 * @jest-environment jsdom
 */

import React from 'react';
import '@testing-library/jest-dom';
import { render } from '@testing-library/react';
import App from './App';

test('renders learn react link', () => {
  const { getByText } = render(<App />);
  const linkElement = getByText(/Tablet/i);
  expect(linkElement).toBeInTheDocument();
});

setupTests.ts

// jest-dom adds custom jest matchers for asserting on DOM nodes.
// allows you to do things like:
// expect(element).toHaveTextContent(/react/i)
// learn more: https://github.com/testing-library/jest-dom
import '@testing-library/jest-dom';

package.json // create-react-app eject

{
  "name": "react-assignment",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "jest-environment-jsdom": "^27.0.6",
    "@babel/core": "^7.16.0",
    "@pmmmwh/react-refresh-webpack-plugin": "^0.5.3",
    "@svgr/webpack": "^5.5.0",
    "babel-jest": "^27.4.2",
    "babel-loader": "^8.2.3",
    "babel-plugin-named-asset-import": "^0.3.8",
    "babel-preset-react-app": "^10.0.1",
    "bfj": "^7.0.2",
    "browserslist": "^4.18.1",
    "camelcase": "^6.2.1",
    "case-sensitive-paths-webpack-plugin": "^2.4.0",
    "css-loader": "^6.5.1",
    "css-minimizer-webpack-plugin": "^3.2.0",
    "dotenv": "^10.0.0",
    "dotenv-expand": "^5.1.0",
    "eslint": "^8.3.0",
    "eslint-config-react-app": "^7.0.0",
    "eslint-webpack-plugin": "^3.1.1",
    "file-loader": "^6.2.0",
    "fs-extra": "^10.0.0",
    "html-webpack-plugin": "^5.5.0",
    "identity-obj-proxy": "^3.0.0",
    "jest": "^27.4.3",
    "jest-resolve": "^27.4.2",
    "jest-watch-typeahead": "^1.0.0",
    "mini-css-extract-plugin": "^2.4.5",
    "postcss": "^8.4.4",
    "postcss-flexbugs-fixes": "^5.0.2",
    "postcss-loader": "^6.2.1",
    "postcss-normalize": "^10.0.1",
    "postcss-preset-env": "^7.0.1",
    "prompts": "^2.4.2",
    "react": "^17.0.2",
    "react-app-polyfill": "^3.0.0",
    "react-dev-utils": "^12.0.0",
    "react-dom": "^17.0.2",
    "react-refresh": "^0.11.0",
    "resolve": "^1.20.0",
    "resolve-url-loader": "^4.0.0",
    "sass-loader": "^12.3.0",
    "semver": "^7.3.5",
    "source-map-loader": "^3.0.0",
    "style-loader": "^3.3.1",
    "tailwindcss": "^3.0.2",
    "terser-webpack-plugin": "^5.2.5",
    "webpack": "^5.64.4",
    "webpack-dev-server": "^4.6.0",
    "webpack-manifest-plugin": "^4.0.2",
    "workbox-webpack-plugin": "^6.4.1"
  },
  "devDependencies": {
    "@testing-library/jest-dom": "^5.16.1",
    "@testing-library/react": "^12.1.2",
    "@testing-library/user-event": "^13.5.0",
    "@types/jest": "^27.4.0",
    "@types/node": "^17.0.13",
    "@types/react": "^17.0.38",
    "@types/react-dom": "^17.0.11",
    "typescript": "^4.5.5"
  },
  "scripts": {
    "start": "node scripts/start.js",
    "build": "node scripts/build.js",
    "test": "node scripts/test.js"
  },
  "eslintConfig": {
    "extends": "react-app"
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  },
  "jest": {
    "roots": [
      "<rootDir>/src"
    ],
    "collectCoverageFrom": [
      "src/**/*.{js,jsx,ts,tsx}",
      "!src/**/*.d.ts"
    ],
    "setupFiles": [
      "react-app-polyfill/jsdom"
    ],
    "setupFilesAfterEnv": [
      "<rootDir>/src/setupTests.ts"
    ],
    "testMatch": [
      "<rootDir>/src/**/__tests__/**/*.{js,jsx,ts,tsx}",
      "<rootDir>/src/**/*.{spec,test}.{js,jsx,ts,tsx}"
    ],
    "testEnvironment": "jsdom",
    "transform": {
      "^.+\\.(js|jsx|mjs|cjs|ts|tsx)$": "<rootDir>/config/jest/babelTransform.js",
      "^.+\\.css$": "<rootDir>/config/jest/cssTransform.js",
      "^(?!.*\\.(js|jsx|mjs|cjs|ts|tsx|css|json)$)": "<rootDir>/config/jest/fileTransform.js"
    },
    "transformIgnorePatterns": [
      "[/\\\\]node_modules[/\\\\].+\\.(js|jsx|mjs|cjs|ts|tsx)$",
      "^.+\\.module\\.(css|sass|scss)$"
    ],
    "modulePaths": [],
    "moduleNameMapper": {
      "^react-native$": "react-native-web",
      "^.+\\.module\\.(css|sass|scss)$": "identity-obj-proxy"
    },
    "moduleFileExtensions": [
      "web.js",
      "js",
      "web.ts",
      "ts",
      "web.tsx",
      "tsx",
      "json",
      "web.jsx",
      "jsx",
      "node"
    ],
    "watchPlugins": [
      "jest-watch-typeahead/filename",
      "jest-watch-typeahead/testname"
    ],
    "resetMocks": true
  },
  "babel": {
    "presets": [
      "react-app"
    ]
  }
}

Running yarn test shows the following error

 FAIL  src/App.test.tsx
  ✕ renders learn react link (46 ms)

  ● renders learn react link

    ReferenceError: KeyframeEffect is not defined

      10 |   useLayoutEffect(()=>{
      11 |     if (pid === progressId) {
    > 12 |       const keyframes = new KeyframeEffect(
         |                         ^
      13 |           inner.current, 
      14 |           [
      15 |             { transform: 'scaleX(0%)', transformOrigin: 'left center' }, 

      at src/components/Progress/index.tsx:12:25

Any idea how to fix this?

Answer 1

You got this error because jest is not using an actual browser when running test, but a NodeJS environment with jest-dom, which is a mock of many browser feature but unfortunately does not provide the class KeyframeEffect.

You can either mock the KeyframeEffect by yourself

window.KeyframeEffect = class KeyframeEffect {
   // mock class methods here
}

Or prevent this code to be executed in an environment where KeyframeEffect does not exist, example: old browser or testing

useLayoutEffect(() => {
   if (pid === progressId && window.KeyframeEffect) {