Jest test fails with window is not defined

I am trying to get started with state of the art web development learning React/Redux.

Right now I am stuck at getting tests running. For some reason jest fails with

Task :frontend:test 
yarn jest v1.0.2
$ "/Users/gunnar/git/app.oakstair.se/frontend/node_modules/.bin/jest" 
FAIL src/containers/App/App.test.js
  ● Test suite failed to run

 ReferenceError: window is not defined
  
  at Object.<anonymous> (config/polyfills.js:18:1)
  at next (native)
  at process._tickCallback (internal/process/next_tick.js:109:7)

I have googled for a while without any success ...

I had the same issue and I do not believe modifying globals is the way to do it. The issue was because in my jest config I had testEnvironment set to node when it should've been jsdom. For me this setting was located in package.json as defined by the react starter app.

In your package.json add window like global something like this

"jest": {
  "verbose": true,
  "preset": "react-native",
  "setupFiles": ["./jest/setup.js"],
  "testRegex": "(/tests/.*|\\.(test|spec))\\.(ts|tsx|js)$",
  "transformIgnorePatterns": [
    "node_modules/(?!(jest-)?react-native|lottie-react-native)"
  ],
  "globals": {
    "window": {}
  }
}

2021 (Jest 27)

Jest's testEnvironment default used to be jsdom. It was changed to node recently starting with version 27.

You can set testEnvironment: 'jsdom' in your config file to keep using JSDOM.

However 'node' seems to be a lot faster, so you should be mocking browser APIs where possible.

https://jestjs.io/blog/2021/05/25/jest-27

npm i jest-environment-jsdom

index.test.tsx

/**
 * @jest-environment jsdom
 */

If you want to keep testEnvironment set to node, you can configure a global window in your jest.config.js/ts and then mock what you need in your test cases.

Works fine as long as you don't need any advanced features. Same answer as some of the high rated above but including some examples.

import type {Config} from '@jest/types';

const config: Config.InitialOptions = {
  ...jestConfig,
  testEnvironment: "node",
  globals: {
    window: {
     location: {}
    }
  }
};

export default config;

SomeTestCase.spec.ts

test('Is correct href', () => {
  window.location.href = 'https://somedomain.com';
  expect(window.location.href).toBe('https://somedomain.com');
})