jest-codemods

jest-codemods

Codemods that simplify migrating JavaScript test files from Tape and AVA to Jest. We expect to support migrating from other test frameworks in the future.

Codemods are small programs that help you automate changes to your codebase. Think of them as search and replace on steroids. They are executed by the Facebook jscodeshift tool.

This tool is made for trying out Jest on your existing test files. We strive to make the migration as smooth as possible, but some manual intervention and tweaks to your tests are to be expected.

Install

$ npm install -g jest-codemods

This installs the runner as jest-codemods.

Usage (CLI)

$ jest-codemods --help

	Codemods for migrating test files to Jest.

	Usage
	  $ jest-codemods <path> [options]

	path		Files or directory to transform. Can be a glob like src/**.test.js

	Only files using Tape or AVA will be converted.

	Options
	  --force, -f	Bypass Git safety checks and forcibly run codemods
	  --dry, -d		Dry run (no changes are made to files)
	  --parser		The parser to use for parsing your source files (babel | babylon | flow)  [babel]

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

Only files requiring or importing AVA or Tape will be transformed. Notice the console output for errors, manual intervention and tweaks are to be expected.

Usage (jscodeshift)

To make the process as simple as possible, we recommend the jest-codemods CLI that wraps the 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/tape.js test-folder
$ jscodeshift -t node_modules/jest-codemods/dist/transformers/ava.js test-folder

Transformations

In general import / require statements determine if any transformation are carried out. The original code quoting style is preserved. Warnings are made if packages like Proxyquire or Testdouble are used as they can be incompatible with Jest.

AVA transformations

AVA features fully supported:

• t.truthy
• t.falsy
• t.true
• t.false
• t.is
• t.not
• t.deepEqual
• t.notDeepEqual
• t.throws
• t.notThrows
• t.regex
• t.notRegex
• t.ifError
• t.fail
• t.end
• test.before
• test.after
• test.beforeEach
• test.afterEach
• test.skip
• test.only
• test.serial
• test.cb
• currying test e.g. test.cb.serial.only

Warnings for unsupported AVA features:

• t.skip
• t.plan

Tape transformations

Tape features fully supported:

• t.ok
• t.true
• t.assert
• t.notOk
• t.false
• t.notok
• t.error
• t.ifError
• t.ifErr
• t.iferror
• t.equal
• t.equals
• t.isEqual
• t.is
• t.strictEqual
• t.strictEquals
• t.notEqual
• t.notStrictEqual
• t.notStrictEquals
• t.isNotEqual
• t.isNot
• t.not
• t.doesNotEqual
• t.isInequal
• t.deepEqual
• t.isEquivalent
• t.same
• t.notDeepEqual
• t.notEquivalent
• t.notDeeply
• t.notSame
• t.isNotDeepEqual
• t.isNotEquivalent
• t.isInequivalent
• t.throws
• t.doesNotThrow
• t.comment
• t.fail
• t.end
• test.skip
• test options like test({skip: true}, t => {})

Warnings for unsupported Tape features:

• t.timeoutAfter
• t.deepLooseEqual
• t.looseEqual
• t.looseEquals
• t.notDeepLooseEqual
• t.notLooseEqual
• t.notLooseEquals
• t.skip
• t.plan
• test.createStream
• test.onFinish

Inspiration

Thanks to ava-codemods for inspiration.

Contributing

To get started, run:

npm install

When developing:

npm run check  # (runs lint and unit test)
npm run lint
npm run test
npm run test:cov
npm run test:watch

License

MIT