babel-jest
Advanced tools
Package description
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.
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']
}ts-jest is a TypeScript preprocessor with source map support for Jest. It allows you to use Jest to test projects written in TypeScript. It is similar to babel-jest but specifically tailored for TypeScript rather than general Babel transformations.
jest-transform-stub is a package that allows you to stub out resources, like images or styles, during testing with Jest. It is similar to babel-jest in that it transforms assets, but it focuses on non-JavaScript assets instead of JavaScript code.
jest-vue-preprocessor is a preprocessor for Jest to handle .vue files, allowing you to test Vue components. It is similar to babel-jest in the sense that it preprocesses files for testing, but it is specifically designed for Vue components.
Changelog
29.0.0
[expect] [BREAKING] Differentiate between MatcherContext MatcherUtils and MatcherState types (#13141)[jest-circus] Add support for test.failing.each (#13142)[jest-config] [BREAKING] Make snapshotFormat default to escapeString: false and printBasicPrototype: false (#13036)[jest-config] [BREAKING] Remove undocumented collectCoverageOnlyFrom option (#13156)[jest-environment-jsdom] [BREAKING] Upgrade to jsdom@20 (#13037, #13058)[@jest/globals] Add jest.Mocked, jest.MockedClass, jest.MockedFunction and jest.MockedObject utility types (#12727)[jest-mock] [BREAKING] Refactor Mocked* utility types. MaybeMockedDeep and MaybeMocked became Mocked and MockedShallow respectively; only deep mocked variants of MockedClass, MockedFunction and MockedObject are exported (#13123, #13124)[jest-mock] [BREAKING] Change the default jest.mocked helper’s behavior to deep mocked (#13125)[jest-snapshot] [BREAKING] Let babel find config when updating inline snapshots (#13150)[@jest/test-result, @jest/types] [BREAKING] Replace Bytes and Milliseconds types with number (#13155)[jest-worker] Adds workerIdleMemoryLimit option which is used as a check for worker memory leaks >= Node 16.11.0 and recycles child workers as required (#13056, #13105, #13106, #13107)[pretty-format] [BREAKING] Remove ConvertAnsi plugin in favour of jest-serializer-ansi-escapes (#13040)[pretty-format] Allow to opt out from sorting object keys with compareKeys: null (#12443)[jest-config] Fix testing multiple projects with TypeScript config files (#13099)[@jest/expect-utils] Fix deep equality of ImmutableJS Record (#13055)[jest-haste-map] Increase the maximum possible file size that jest-haste-map can handle (#13094)[jest-runtime] Properly support CJS re-exports from dual packages (#13170)[jest-snapshot] Make prettierPath optional in SnapshotState (#13149)[jest-snapshot] Fix parsing error from inline snapshot files with JSX (#12760)[jest-worker] When a process runs out of memory worker exits correctly and doesn't spin indefinitely (#13054)[*] [BREAKING] Drop support for Node v12 and v17 (#13033)[docs] Fix webpack name (#13049)[docs] Explicit how to set n for --bail (#13128)[docs] Update Enzyme URL (#13166)[jest-leak-detector] Remove support for weak-napi (#13035)[jest-snapshot] [BREAKING] Require rootDir as argument to SnapshotState (#13150)Readme
If you are already using jest-cli, add babel-jest and it will automatically compile JavaScript code using Babel.
yarn add --dev babel-jest @babel/core
If you would like to write your own preprocessor, uninstall and delete babel-jest and set the config.transform option to your preprocessor.
Note: this step is only required if you are using babel-jest with additional code preprocessors.
To explicitly define babel-jest as a transformer for your JavaScript code, map .js files to the babel-jest module. Typescript files are also supported.
"transform": {
"\\.[jt]sx?$": "babel-jest"
},
FAQs
Jest plugin to use babel for transformation.
The npm package babel-jest receives a total of 23,781,031 weekly downloads. As such, babel-jest popularity was classified as popular.
We found that babel-jest demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 3 open source maintainers collaborating on the project.
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