The babel-jest package is a Jest plugin that makes it easy to use Babel to transform your JavaScript tests. It automatically hooks Babel into Jest and compiles files before running them, allowing you to use the latest JavaScript features and syntax in your test files.

What are babel-jest's main functionalities?

Transforming test files with Babel

This configuration in Jest's setup file tells Jest to use babel-jest for transforming any files that match the regex pattern (in this case, any JavaScript files) before running the tests.

module.exports = {
  transform: {
    '^.+\\.js$': 'babel-jest'
  }
};

Using modern JavaScript syntax in tests

With babel-jest, you can write tests using modern JavaScript features like async/await without worrying about compatibility issues.

test('async/await works', async () => {
  const data = await fetchData();
  expect(data).toBe('expected data');
});

Custom Babel configuration

babel-jest allows you to specify a custom Babel configuration to tailor the transformation process to your project's needs.

{
  'presets': [['@babel/preset-env', { 'targets': { 'node': 'current' } }]],
  'plugins': ['@babel/plugin-proposal-class-properties']
}

Other packages similar to babel-jest

Changelog

Source

26.0.0

Features

[jest-environment-jsdom] [BREAKING] Upgrade jsdom to v16 (#9606)
[@jest/fake-timers] Add possibility to use a modern implementation of fake timers, backed by @sinonjs/fake-timers (#7776)
[jest-runtime] Add createMockFromModule as an alias for genMockFromModule (#9962)

Fixes

[babel-jest] Handle null being passed to createTransformer (#9955)
[jest-circus, jest-console, jest-jasmine2, jest-reporters, jest-util, pretty-format] Fix time durating formatting and consolidate time formatting code (#9765)
[jest-circus] [BREAKING] Fail tests if a test takes a done callback and have return values (#9129)
[jest-circus] [BREAKING] Throw a proper error if a test / hook is defined asynchronously (#8096)
[jest-circus] Throw more descriptive error if hook is defined inside test (#9957)
[jest-circus] [BREAKING] Align execution order of tests to match jasmine's top to bottom order (#9965)
[jest-config, jest-resolve] [BREAKING] Remove support for browser field (#9943)
[jest-haste-map] Stop reporting files as changed when they are only accessed (#7347)
[jest-resolve] Show relative path from root dir for module not found errors (#9963)
[jest-runtime] Fix absolute path moduleNameMapper + jest.mock bug (#8727)

Chore & Maintenance

[*] [BREAKING] TypeScript definitions requires a minimum of TypeScript v3.8 (#9823)
[*] [BREAKING] Drop support for Node 8 (#9423)
[*] Upgrade to chalk@4 (#9752)
[*] Remove usage of realpath-native (#9952)
[docs] Fix example reference implementation to use Jest with Phabricator (#8662)
[docs] Added default compiler to transform (#8583)
[docs] Updated Testing Frameworks guide with React; make it generic (#9106)
[expect, jest-mock, pretty-format] [BREAKING] Remove build-es5 from package (#9945)
[@jest/fake-timers, @jest/environment] [BREAKING] Rename LolexFakeTimers to ModernFakeTimers (#9960)
[jest-haste-map] [BREAKING] removed providesModuleNodeModules (#8535)
[jest-runtime] [BREAKING] Remove long-deprecated require.requireActual and require.requireMock methods (#9854)

Readme

Source

babel-jest

Babel jest plugin

Usage

Make the following changes to package.json:

{
  "devDependencies": {
    "babel-jest": "*",
    "jest-cli": "*"
  },
  "scripts": {
    "test": "jest"
  },
  "jest": {
    "scriptPreprocessor": "<rootDir>/node_modules/babel-jest",
    "testFileExtensions": ["es6", "js"],
    "moduleFileExtensions": ["js", "json", "es6"]
  }
}

And run:

$ npm install

And you're good to go!

FAQs

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Package last updated on 07 Nov 2015

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