If you'd like to try out Jest with an existing codebase, there are a number of ways to convert to Jest:
If you are using AVA, Chai, Expect.js (by Automattic), Jasmine, Mocha, proxyquire, Should.js or Tape you can use the third-party jest-codemods to do most of the dirty migration work. It runs a code transformation on your codebase using jscodeshift.
Install Jest Codemods with npm
by running:
npm install -g jest-codemods
To transform your existing tests, navigate to the project containing the tests and run:
jest-codemods
More information can be found at https://github.com/skovhus/jest-codemods.
© 2014–present Facebook Inc.
Licensed under the BSD License.
https://facebook.github.io/jest/docs/en/migration-guide.html