What is Jest?

Jest provides you with multiple layers on top of Jasmine.
Jest is a tool in the Javascript Testing Framework category of a tech stack.
Jest is an open source tool with 30.3K GitHub stars and 4.3K GitHub forks. Here鈥檚 a link to Jest's open source repository on GitHub

Who uses Jest?

Companies
534 companies reportedly use Jest in their tech stacks, including Airbnb, Facebook, and Instagram.

Developers
1352 developers on StackShare have stated that they use Jest.

Jest Integrations

SilverStripe, Glamorous, Wallaby.js, Just, and Majestic GUI are some of the popular tools that integrate with Jest. Here's a list of all 6 tools that integrate with Jest.

Why developers like Jest?

Here鈥檚 a list of reasons why companies and developers use Jest
Private Decisions at about Jest
Private to your company

Here are some stack decisions, common use cases and reviews by members of with Jest in their tech stack.

redux-saga
redux-saga
Redux
Redux
React
React
redux-thunk
redux-thunk
Jest
Jest

Choosing redux-saga for my async Redux.js middleware, for a React application, instead of the typical redux-thunk .

Redux-saga is much easier to test than Redux-thunk - it requires no module mocking at all. Converting from redux-thunk to redux-saga is easy enough, as you are only refactoring the action creators - not your redux store or your react components. I've linked a github repo that shows the same solution with both, including Jest tests.

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Volkan 脰z莽elik
Volkan 脰z莽elik
Chief Executive Philosopher at volkan.io | 2 upvotes 43 views
Jest
Jest

Jest is my unit-testing tool of choice.

Almost all unit testing suites (Mocha, Jasmine, etc.) are more or less the same.

The main advantage I guess, is that it integrates pretty well with React and Enzyme. Jest

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Scott Mebberson
Scott Mebberson
CTO / Chief Architect at Idearium | 2 upvotes 36K views
Mocha
Mocha
Jest
Jest

We used to Mocha for as our primary Node.js test framework. We've now switched to Jest and haven't looked back.

Jest is faster and requires less setup and configuration. The Mocha API and eco-system is vast and verified, but that also brings complexity.

It you want to get in, write tests, execute them and get out, try Jest 馃榾

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Gustavo Mu帽oz
Gustavo Mu帽oz
Web UI Developer at Globant | 1 upvotes 3.1K views
Jest
Jest
Enzyme
Enzyme

I really enjoy using Jest as my testing framework. I also use Enzyme to complement, and both together are amazing. Jest is fast and easy to use, It has all you need together under the same tool, and it's pretty easy to create all kind of test, even asynchronous ones. I was responsible for implant it in our company projects, and it was the best decision for testing.

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Jasmine
Jasmine
Karma
Karma
Angular CLI
Angular CLI
Jest
Jest
Visual Studio Code
Visual Studio Code

Switched from Jasmine with Karma that come setup by Angular CLI to use Jest instead, since Jasmine and Karma were very finicky in my setup and had to be reconfigured frequently to run tests properly.

Jest was also easier to integrate into my workflow with Visual Studio Code.

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Cypress
Cypress
Jest
Jest

As we all know testing is an important part of any application. To assist with our testing we are going to use both Cypress and Jest. We feel these tools complement each other and will help us get good coverage of our code. We will use Cypress for our end to end testing as we've found it quite user friendly. Jest will be used for our unit tests because we've seen how many larger companies use it with great success.

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Public Decisions about Jest

Here are some stack decisions, common use cases and reviews by companies and developers who chose Jest in their tech stack.

Ruby
Ruby
Rails
Rails
React
React
Redux
Redux
Create React App
Create React App
Jest
Jest
react-testing-library
react-testing-library
RSpec
RSpec
PostgreSQL
PostgreSQL
MongoDB
MongoDB
Redis
Redis
React Native
React Native
Next.js
Next.js
Python
Python
Bit
Bit
JavaScript
JavaScript

I'm working as one of the engineering leads in RunaHR. As our platform is a Saas, we thought It'd be good to have an API (We chose Ruby and Rails for this) and a SPA (built with React and Redux ) connected. We started the SPA with Create React App since It's pretty easy to start.

We use Jest as the testing framework and react-testing-library to test React components. In Rails we make tests using RSpec.

Our main database is PostgreSQL, but we also use MongoDB to store some type of data. We started to use Redis 聽for cache and other time sensitive operations.

We have a couple of extra projects: One is an Employee app built with React Native and the other is an internal back office dashboard built with Next.js for the client and Python in the backend side.

Since we have different frontend apps we have found useful to have Bit to document visual components and utils in JavaScript.

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Robert Zuber
Robert Zuber
CTO at CircleCI | 17 upvotes 477.2K views
atCircleCICircleCI
Next.js
Next.js
React
React
Storybook
Storybook
TypeScript
TypeScript
Emotion
Emotion
GraphQL
GraphQL
Apollo
Apollo
Jest
Jest
Percy
Percy
Cypress
Cypress

We are in the process of adopting Next.js as our React framework and using Storybook to help build our React components in isolation. This new part of our frontend is written in TypeScript, and we use Emotion for CSS/styling. For delivering data, we use GraphQL and Apollo. Jest, Percy, and Cypress are used for testing.

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Eli Hooten
Eli Hooten
CTO at Codecov | 16 upvotes 65.4K views
atCodecovCodecov
Vue.js
Vue.js
Python
Python
vuex
vuex
Jest
Jest

We chose Vue.js at Codecov to replace a front end that was based mostly on server side rendered Python templates, and was getting fairly long in the tooth. The move to Vue.js allowed us to take a more component driven approach to our front end, providing greater flexibility and reuse when creating new pages and refactoring old ones. Another bonus was how easily we could integrate Axios with VueJS for making AJAX calls within Vue.js components and their associated vuex stores. We were also able to easily integrate Vue.js with the Jest testing framework, which allowed to provide test coverage for a front end where none previously existed.

The move to Vue.js has allowed us to be more agile in our front end development by further decoupling our front end from our back end. Additionally, by fully embracing a component-driven approach, we're able to more easily isolate and test functionality, leading to a more readible, maintainable, and extensible front end codebase.

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redux-saga
redux-saga
Redux
Redux
React
React
redux-thunk
redux-thunk
Jest
Jest

Choosing redux-saga for my async Redux.js middleware, for a React application, instead of the typical redux-thunk .

Redux-saga is much easier to test than Redux-thunk - it requires no module mocking at all. Converting from redux-thunk to redux-saga is easy enough, as you are only refactoring the action creators - not your redux store or your react components. I've linked a github repo that shows the same solution with both, including Jest tests.

See more
Cypress
Cypress
Jest
Jest

As we all know testing is an important part of any application. To assist with our testing we are going to use both Cypress and Jest. We feel these tools complement each other and will help us get good coverage of our code. We will use Cypress for our end to end testing as we've found it quite user friendly. Jest will be used for our unit tests because we've seen how many larger companies use it with great success.

See more
Dschinkel Schinkel
Dschinkel Schinkel
Mocha
Mocha
Jest
Jest
JavaScript
JavaScript
React
React
Enzyme
Enzyme
#Tdd
#Bdd
#Testdrivendevelopment

I use both mocha and Jest because:

  • I don't care whether teams use Jest or Mocha. But jest is way too overhyped. Most devs are writing integration tests and think that it's so much better but frankly I don't write integration tests as the way to get both design feedback and confidence when I code. I adhere to the test pyramid, not ice cream cone or the dumb "trophy"

  • I TDD, so I only ever use the "API" of test frameworks. I don't do a lot of integration tests for TDD and all the bells and whistles Jest provides you from the command-line I just don't need. And I certainly do not care about or touch Jest Snapshots, I despise them

  • My tests are fast enough because I write isolated tests with TDD, so I don't run into performance issues. Example: I write my tests in a way that I can run 300 tests in literally 1 second with mocha. So the Jest ability to pinpoint and only run those tests which are affected by code changes. I want to run all of them every time when I TDD. It's a different mindset when you TDD

  • I also mainly code in IntelliJ or WebStorm because I feel the tools in that IDE far surpass VSCode and I also love running the test UI runner in it vs. lousy command-line

  • I feel both mocha and Jest read just fine in terms of code readability. Jest might have shorter assertion syntax but I don't really care. I just care that I can read the damn test and my tests are written well and my test descriptions, as well as the code itself including constants represent business language, not technical. I care most about BDD, clean code, 4 rules of simple design, and SOLID

  • I don't like using mock frameworks so no I don't use Jest's Mocking framework. I don't have to mock a lot in my tests due to the nature of how I strive to code...I keep my design simple and modular using principals such as clean code and 4 rules of simple design. If I must mock, I create very simple custom mocks with JS

  • On the contrary to the belief that integration tests and mount are the way to go (this belief drives me absolutely crazy, especially Dodd's promoting that), I TDD with shallow & enzyme. My tests are simple. My design is driven by my tests and my tests give me quick and useful feedback. I have a course I'm working on coming out soon on TDD with React to show you how to truly test the FE and why the ice cream cone and trophy suck (you're being scammed people). Watch for that here: https://twitter.com/DaveSchinkel/status/1062267649235791873

Don't forget to upvote this post!

Mocha Jest JavaScript React @jsdom Enzyme #tdd #bdd #testdrivendevelopment

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Jest's Features

  • Familiar Approach: Built on top of the Jasmine test framework, using familiar expect(value).toBe(other) assertions
  • Mock by Default: Automatically mocks CommonJS modules returned by require(), making most existing code testable
  • Short Feedback Loop: DOM APIs are mocked and tests run in parallel via a small node.js command line utility

Jest Alternatives & Comparisons

What are some alternatives to Jest?
Mocha
Mocha is a feature-rich JavaScript test framework running on node.js and the browser, making asynchronous testing simple and fun. Mocha tests run serially, allowing for flexible and accurate reporting, while mapping uncaught exceptions to the correct test cases.
Selenium
Selenium automates browsers. That's it! What you do with that power is entirely up to you. Primarily, it is for automating web applications for testing purposes, but is certainly not limited to just that. Boring web-based administration tasks can (and should!) also be automated as well.
AVA
Even though JavaScript is single-threaded, IO in Node.js can happen in parallel due to its async nature. AVA takes advantage of this and runs your tests concurrently, which is especially beneficial for IO heavy tests. In addition, test files are run in parallel as separate processes, giving you even better performance and an isolated environment for each test file.
Enzyme
Enzyme is a JavaScript Testing utility for React that makes it easier to assert, manipulate, and traverse your React Components' output.
Jasmine
Jasmine is a Behavior Driven Development testing framework for JavaScript. It does not rely on browsers, DOM, or any JavaScript framework. Thus it's suited for websites, Node.js projects, or anywhere that JavaScript can run.
See all alternatives

Jest's Followers
1434 developers follow Jest to keep up with related blogs and decisions.
tunaung2048
Juan Jose Prieto
Peyman Eskandari
Mateusz R
Max Melnychuk
sivasai thota
Sumeet Dewangan
Swetha Sunil Kumar (CONT)
vipr0
washim raza