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https://github.com/skovhus/jest-codemods

Codemods for migrating to Jest https://github.com/facebook/jest 👾
https://github.com/skovhus/jest-codemods

ava chai codemod codemods jest jest-codemods jscodeshift mocha tape testing

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Codemods for migrating to Jest https://github.com/facebook/jest 👾

Awesome Lists containing this project

README 

        


 jest-codemods 👾



Codemods that simplify migrating JavaScript and TypeScript test files from

[AVA](https://github.com/avajs/ava),

[Chai](https://github.com/chaijs/chai),

[Expect.js (by Automattic)](https://github.com/Automattic/expect.js),

[[email protected] (by mjackson)](https://github.com/mjackson/expect),

[Jasmine](https://github.com/jasmine/jasmine),

[Mocha](https://github.com/mochajs/mocha),

[proxyquire](https://github.com/thlorenz/proxyquire),

[Should.js](https://github.com/tj/should.js/),

[Tape](https://github.com/substack/tape),

[Sinon](https://github.com/sinonjs/),

and

[Node-Tap](https://github.com/tapjs/node-tap)

to [Jest](https://facebook.github.io/jest/).



[![version][version-badge]][package]

[![downloads](https://img.shields.io/npm/dm/jest-codemods.svg?style=flat-square)](http://npm-stat.com/charts.html?package=jest-codemods&from=2017-07-17)

[![Code Coverage](https://img.shields.io/codecov/c/github/skovhus/jest-codemods.svg?style=flat-square)](https://codecov.io/github/skovhus/jest-codemods)

[![MIT License](https://img.shields.io/npm/l/jest-codemods.svg?style=flat-square)](https://github.com/skovhus/jest-codemods/blob/master/LICENSE)

[![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg?style=flat-square)](http://makeapullrequest.com)









Codemods are small programs that help you automate changes to your codebase.

Think of them as search and replace on steroids.



We made jest-codemods so you can try out Jest on your existing codebase.

We strive to make the migration as smooth as possible, but some manual intervention

and tweaks to your tests are to be expected.



## Usage (CLI)



To use the interactive CLI run



	$ npx jest-codemods



If you do not have `npx` installed, you can install the `jest-codemods` command globally by running `npm install -g jest-codemods`.



For more options

```

$ npx jest-codemods --help



    Usage:      npx jest-codemods  [options]



    Examples:   npx jest-codemods src

                npx jest-codemods src/**/*.test.js



    Options:

      -f, --force       Bypass Git safety checks and force codemods to run

      -d, --dry         Dry run (no changes are made to files)

```



To transform all test files in a directory run `jest-codemods .` in your terminal.



Notice the console output for errors, manual intervention and tweaks might be required.



## Usage (jscodeshift)



To make the process as simple as possible, we recommend the `jest-codemods` CLI

that wraps the [jscodeshift](https://github.com/facebook/jscodeshift) executable.

But you can also run the transformations directly using `jscodeshift`.



```

$ npm install -g jscodeshift

$ npm install jest-codemods

$ jscodeshift -t node_modules/jest-codemods/dist/transformers/ava.js test-folder

$ jscodeshift -t node_modules/jest-codemods/dist/transformers/chai-assert.js test-folder

$ jscodeshift -t node_modules/jest-codemods/dist/transformers/chai-should.js test-folder

$ jscodeshift -t node_modules/jest-codemods/dist/transformers/expect-js.js test-folder

$ jscodeshift -t node_modules/jest-codemods/dist/transformers/expect.js test-folder

$ jscodeshift -t node_modules/jest-codemods/dist/transformers/jasmine-globals.js test-folder

$ jscodeshift -t node_modules/jest-codemods/dist/transformers/jasmine-this.js test-folder

$ jscodeshift -t node_modules/jest-codemods/dist/transformers/mocha.js test-folder

$ jscodeshift -t node_modules/jest-codemods/dist/transformers/should.js test-folder

$ jscodeshift -t node_modules/jest-codemods/dist/transformers/tape.js test-folder

$ jscodeshift -t node_modules/jest-codemods/dist/transformers/sinon.js test-folder

$ jscodeshift -t node_modules/jest-codemods/dist/transformers/jest-globals-import.js test-folder

```



## Test environment: Jest on Node.js or other



If you're using Jest as your test runner and executing tests on Node.js, you'll want to use

the default option when prompted. In this case, `jest-codemods` assumes that global values

such as `expect` and `jest` are provided and will not `require()` them explicitly.



If, however, you are using a different test runner or executing Jest tests in a browser,

you may need to choose the option with explicit `require()` calls.



In the second case, after running `jest-codemods`, you might need to install a few dependencies:



    yarn add --dev expect jest-mock



    npm install --save-dev expect jest-mock



    pnpm install --save-dev expect jest-mock



## Transformations



If possible `import` / `require` statements determine if any transformation are carried out.

The original code quoting style is preserved.

Warnings are made if packages are used that are incompatible with Jest.



## Inspiration



Thanks to [avajs/ava-codemods](https://github.com/avajs/ava-codemods) for inspiration and original CLI setup.



The Mocha and Chai assert support began its life at [paularmstrong/mocha-to-jest-codemod](https://github.com/paularmstrong/mocha-to-jest-codemod).



Chai Should/Expect came from [AlexJuarez/chai-to-jasmine](https://github.com/AlexJuarez/chai-to-jasmine).



## Links



- Official Jest migration guide https://jestjs.io/docs/en/migration-guide

- "Migrating 2,000+ Specs from Karma to Jest" https://labs.contactually.com/migrating-2-000-specs-from-karma-to-jest-25dd8b0f3cfb

- "Into the Great Unknown — Migrating from Mocha to Jest" https://ebaytech.berlin/into-the-great-unknown-migrating-from-mocha-to-jest-3baced083c7e

- "Automate your migration to Jest using codemods" Egghead video https://egghead.io/lessons/jest-automate-your-migration-to-jest-using-codemods

- "Migrating Ava to Jest" https://codedaily.io/tutorials/11/Migrating-Ava-to-Jest

- "Switching from Ava to Jest for TypeScript" https://shift.infinite.red/switching-from-ava-to-jest-for-typescript-a6dac7d1712f

- "Migrating a Mocha project to Jest Test Framework" https://medium.com/@liran.tal/migrating-a-mocha-project-to-jest-test-framework-76d13d76685

- "Migrating to Jest on the P2P team at PayPal" https://blog.kentcdodds.com/migrating-to-jest-881f75366e7e



## Contributing



To get started, run:



	pnpm install



When developing:



	pnpm verify  # (build/lint/test)

	pnpm build

	pnpm lint

	pnpm test

	pnpm test:cov

	pnpm test:watch



## License



MIT



[version-badge]: https://img.shields.io/npm/v/jest-codemods.svg?style=flat-square

[package]: https://www.npmjs.com/package/jest-codemods