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, you can do …

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 function that …

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 popular JS libraries.

Note: babel-jest is automatically installed when installing Jest and will automatically transform files if a babel configuration exists in your project. To avoid this behavior, you can explicitly reset the …

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 exactly …

You can cherry pick specific features of Jest and use them as standalone packages. Here's a list of the available packages:

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 Jest's …

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. Look at the full …

The jest object is automatically in scope within every test file. The methods in the jest object help create mocks and let you control Jest's overall behavior. It can also be imported explicitly by via import from …

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 gives you results …