facebook/jest

github：https://github.com/facebook/jest

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Up to 2016.09.21

What is jest?

Jest is a JavaScript unit testing framework, used by Facebook to test services and React applications.

Features

• Adaptable
  Jest uses Jasmine assertions by default and Jest is modular, extendible and configurable.

• Sandboxed and Fast
  Jest virtualizes JavaScript environments, provides browser mocks and runs tests in parallel across workers.

• Snapshot Testing
  Jest can capture snapshots of React trees or other serializable values to write tests quickly and it provides a seamless update experience.

Why use jest?

• Jest automatically finds tests to execute in your repo

• It sandboxes test files, and resets state automatically for every test.

• Jest allows you to test asynchronous code synchronously as well as Promises and async/await.

• Uses static analysis to find and only run relevant test files during local development.

• Runs your tests with a fake DOM implementation (via jsdom) on the command line.

• Runs tests in parallel processes to minimize test runtime.

• It works with any compile-to-JS language and integrates seamlessly with Babel.

• Jest provides a manual mocking library. And it creates coverage reports.