Jest is a JavaScript testing framework designed to ensure correctness of any JavaScript codebase. It allows you to write tests with an approachable, familiar and feature-rich API that …

You can run Jest directly from the CLI (if it's globally available in your PATH, e.g. by yarn global add jest or npm install jest --global) with a variety of useful options.

See React: Function and Class Components. Reminders that with Class components, we expect Jest to be used to test props and not methods directly. Now let's use React's test renderer and …

In your test files, Jest puts each of these methods and objects into the global environment. You don't have to require or import anything to use them. However, if you prefer explicit imports, …

Jest runs the code of your project as JavaScript, hence a transformer is needed if you use some syntax not supported by Node out of the box (such as JSX, TypeScript, Vue templates).

Jest is a universal testing platform, with the ability to adapt to any JavaScript library or framework. In this section, we'd like to link to community posts and articles about integrating Jest into …

Note: Jest documentation uses yarn commands, but npm will also work. You can compare yarn and npm commands in the yarn docs, here. Let's get started by writing a test for a hypothetical …

The jest command line runner has a number of useful options. You can run jest --help to view all available options. Many of the options shown below can also be used together to run tests …

Jest adds the inlineSnapshot string argument to the matcher in the test file (instead of an external .snap file) the first time that the test runs. Check out the section on Inline Snapshots for more …

Browse the docs Find what you're looking for in our detailed documentation and guides. Learn how to get started with Jest. Troubleshoot problems with Jest. Learn how to configure Jest. …