Jest

Jest

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Get StartedDocsConfigGet help

Jest is a delightful JavaScript Testing Framework with a focus on simplicity.

It works with projects using: Babel, TypeScript, Node, React, Angular, Vue and more!

Zero config

Jest aims to work out of the box, config free, on most JavaScript projects.

Snapshots

Make tests which keep track of large objects with ease. Snapshots live either alongside your tests, or embedded inline.

Isolated

Tests are parallelized by running them in their own processes to maximize performance.

Great api

From it to expect - Jest has the entire toolkit in one place. Well documented, well maintained, well good.

Fast and safe

By ensuring your tests have unique global state, Jest can reliably run tests in parallel. To make things quick, Jest runs previously failed tests first and re-organizes runs based on how long test files take.

Code coverage

Generate code coverage by adding the flag --coverage. No additional setup needed. Jest can collect code coverage information from entire projects, including untested files.

Easy Mocking

Jest uses a custom resolver for imports in your tests making it simple to mock any object outside of your test’s scope. You can use mocked imports with the rich Mock Functions API to spy on function calls with readable test syntax.

Great Exceptions

Tests fail, when they do Jest provides rich context why, here’s some examples:

Philosophy

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 quickly.

Jest is well-documented, requires little configuration and can be extended to match your requirements.

Jest makes testing delightful.

- Jest Core Team

- Jest Core Team

Docs and talks

The Jest core team and contributors regularly speak about Jest and Delightful JavaScript Testing. Check out our talk about Building High-Quality JavaScript Tools at jsconf.eu 2017 and our talk about Jest as a Platform at ReactiveConf 2017.

Open Collective

With so many users, the core team of Jest uses an Open Collective for non-Facebook contributors.

Sponsors

Sponsors are those who contribute $100 or more per month to Jest

Facebook Open Source's avatarPrincipal Financial Group's avatarFrontend Masters's avatarYakaz's avatarTrueVendor's avatarTriplebyte's avatar

Backers

Backers are those who contribute $2 or more per month to Jest

Airbnb's avatarAaron Abramov's avatarKent C. Dodds's avatarMarcel Guerin's avatarCodePilot.ai's avatarFilipe Guerra's avatarPhilipp Spieß's avatarJava Tutorial's avatarRan Yitzhaki's avatarEduardo Rabelo's avatarKent Dodds's avatarBrian Jacobel's avatarDaniel Arthur Gallagher's avatarCodeFirst's avatarakameco's avatarRyota Murakami's avatarBootstrap Build's avatarLaflume's avatarHostPresto's avatarJehong Ahn's avatarTLDR Newsletter's avatarMatan Kushner's avatarTrevor Waddell's avatarMatter's avatarUldis Sturms's avatarAdult Work's avatarAdSpeed AdServer's avatarBryan Cardillo's avatarGil Barbara's avatarAdultseek's avatarHRANK.com's avatarThe Gobeliners's avatarAandelen Kopen's avatarVPS Server's avatarGustavo Muñoz's avatarTestingBot's avatarTakeShape's avatarWill Ceolin's avatarMoustafa M's avatarJean-Luc Geering's avatarTomasz Wojciechowski's avatarLink Directory's avatarMaid2Clean's avatarTalentPlot's avatarBigtimedaily.com's avatarCasinoExpo's avatarCasinoidag's avatarNorgelån.com's avatarDavidson Fellipe's avatarDatantify's avatarPiscine Advisor's avatarFreespin.nu's avatarDivyanshu Maithani's avatarUnhype's avatarKodi Addons's avatarFirestick Apps's avatarReid Burke's avatarCinema HD's avatar

Who uses Jest?

A lot of people! With 8.5m downloads in the last 30 days, and used on over 500,000 public repos on GitHub. Jest is used extensively at these companies:

And many others

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