Jest vs Yarn

Overview

Jest

Stacks15.2K

Followers4.1K

Votes175

Yarn

Stacks28.2K

Followers13.5K

Votes151

GitHub Stars41.5K

Forks2.7K

Jest vs Yarn: What are the differences?

< Introduction: >

Jest and Yarn are both popular tools used in web development. While Jest is a testing framework, Yarn is a package manager. Understanding the key differences between the two can help developers choose the most appropriate tool for their needs.

Installation: Jest is easily installed through npm, the Node.js package manager, by running a simple command in the terminal. On the other hand, Yarn itself is installed by running a specific command, but it also requires Node.js to be pre-installed.
Functionality: Jest is focused on providing a comprehensive and feature-rich testing solution for JavaScript code, supporting various testing types such as unit, integration, and snapshot testing. It offers powerful options like mocking and code coverage analysis. Conversely, Yarn is primarily designed to manage packages and dependencies efficiently, ensuring reproducible builds and faster installations.
Configuration and Usage: Jest comes with a predefined configuration, making it easy to get started with testing. It uses a simple API for writing test cases and provides command-line utilities for running tests. Yarn, on the other hand, requires a separate configuration file (typically a package.json) to define project-specific settings and dependencies. It offers a command-line interface for managing packages, running scripts, and executing other package-related tasks.
Compatibility: Jest is commonly used in conjunction with the React library and is specifically optimized for testing React applications. It provides built-in support for React features like component rendering and snapshot testing. Yarn, on the other hand, can be used with various package managers, including npm, making it compatible with a wide range of JavaScript projects and frameworks.
Community Support and Adoption: Jest, developed and maintained by Facebook, has gained significant popularity and enjoys a vibrant open-source community. It has become the de facto choice for many JavaScript developers and has extensive documentation and community resources. Yarn, developed by Facebook in collaboration with other companies, is also widely adopted but its community is relatively smaller compared to Jest.
Performance and Speed: Jest is known for its fast and parallel test execution, which can significantly reduce the time required for running tests. It optimizes test runs by executing only the necessary tests based on file changes. Yarn, while not directly related to test execution, is focused on improving package installation speed by leveraging caching and parallelization.

In summary, Jest is a powerful testing framework with a React-centric approach, while Yarn is a package manager aimed at efficient dependency management. Choosing between the two depends on the specific needs of a project, with Jest being more suitable for testing and Yarn being more focused on package management.

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Advice on Jest, Yarn

StackShare

Apr 23, 2019

Needs adviceon

Node.js

npm

Yarn

From a StackShare Community member: “I’m a freelance web developer (I mostly use Node.js) and for future projects I’m debating between npm or Yarn as my default package manager. I’m a minimalist so I hate installing software if I don’t need to- in this case that would be Yarn. For those who made the switch from npm to Yarn, what benefits have you noticed? For those who stuck with npm, are you happy you with it?"

294k views294k

Comments

Dane

Feb 7, 2020

Needs adviceon

Cypress

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.

836k views836k

Comments

zen-li

Apr 24, 2019

Reviewon

Yarn

p.s.

I am not sure about the performance of the latest version of npm, whether it is different from my understanding of it below. Because I use npm very rarely when I had the following knowledge.

------⏬

I use Yarn because, first, yarn is the first tool to lock the version. Second, although npm also supports the lock version, when you use npm to lock the version, and then use package-lock.json on other systems, package-lock.json Will be modified. You understand what I mean, when you deploy projects based on Git...

250k views250k

Comments

Detailed Comparison

Jest	Yarn
Jest provides you with multiple layers on top of Jasmine.	Yarn caches every package it downloads so it never needs to again. It also parallelizes operations to maximize resource utilization so install times are faster than ever.
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	-
Statistics
GitHub Stars -	GitHub Stars 41.5K
GitHub Forks -	GitHub Forks 2.7K
Stacks 15.2K	Stacks 28.2K
Followers 4.1K	Followers 13.5K
Votes 175	Votes 151
Pros & Cons
Pros 36 Open source 32 Mock by default makes testing much simpler 23 Testing React Native Apps 20 Parallel test running 16 Fast Cons 4 Ambiguous configuration 4 Documentation 3 Difficult 2 Bugged 2 Ambiguous	Pros 85 Incredibly fast 22 Easy to use 13 Open Source 11 Can install any npm package 8 Works where npm fails Cons 16 Facebook 7 Sends data to facebook 4 Should be installed separately 3 Cannot publish to registry other than npm
Integrations
No integrations available	JavaScript npm

What are some alternatives to Jest, Yarn?

npm

npm is the command-line interface to the npm ecosystem. It is battle-tested, surprisingly flexible, and used by hundreds of thousands of JavaScript developers every day.

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.

RequireJS

RequireJS loads plain JavaScript files as well as more defined modules. It is optimized for in-browser use, including in a Web Worker, but it can be used in other JavaScript environments, like Rhino and Node. It implements the Asynchronous Module API. Using a modular script loader like RequireJS will improve the speed and quality of your code.

Browserify

Browserify lets you require('modules') in the browser by bundling up all of your dependencies.

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.

Cypress

Cypress is a front end automated testing application created for the modern web. Cypress is built on a new architecture and runs in the same run-loop as the application being tested. As a result Cypress provides better, faster, and more reliable testing for anything that runs in a browser. Cypress works on any front-end framework or website.

CodeceptJS

It is a modern end to end testing framework with a special BDD-style syntax. The test is written as a linear scenario of user's action on a site. Each test is described inside a Scenario function with I object passed into it.

Protractor

Protractor is an end-to-end test framework for Angular and AngularJS applications. Protractor runs tests against your application running in a real browser, interacting with it as a user would.

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.

Ghost Inspector

It lets you create and manage UI tests that check specific functionality in your website or application. We execute these automated browser tests continuously from the cloud and alert you if anything breaks.

Related Comparisons

Jest vs Yarn: What are the differences?

< Introduction: >

Installation: Jest is easily installed through npm, the Node.js package manager, by running a simple command in the terminal. On the other hand, Yarn itself is installed by running a specific command, but it also requires Node.js to be pre-installed.
Functionality: Jest is focused on providing a comprehensive and feature-rich testing solution for JavaScript code, supporting various testing types such as unit, integration, and snapshot testing. It offers powerful options like mocking and code coverage analysis. Conversely, Yarn is primarily designed to manage packages and dependencies efficiently, ensuring reproducible builds and faster installations.
Configuration and Usage: Jest comes with a predefined configuration, making it easy to get started with testing. It uses a simple API for writing test cases and provides command-line utilities for running tests. Yarn, on the other hand, requires a separate configuration file (typically a package.json) to define project-specific settings and dependencies. It offers a command-line interface for managing packages, running scripts, and executing other package-related tasks.
Compatibility: Jest is commonly used in conjunction with the React library and is specifically optimized for testing React applications. It provides built-in support for React features like component rendering and snapshot testing. Yarn, on the other hand, can be used with various package managers, including npm, making it compatible with a wide range of JavaScript projects and frameworks.
Community Support and Adoption: Jest, developed and maintained by Facebook, has gained significant popularity and enjoys a vibrant open-source community. It has become the de facto choice for many JavaScript developers and has extensive documentation and community resources. Yarn, developed by Facebook in collaboration with other companies, is also widely adopted but its community is relatively smaller compared to Jest.
Performance and Speed: Jest is known for its fast and parallel test execution, which can significantly reduce the time required for running tests. It optimizes test runs by executing only the necessary tests based on file changes. Yarn, while not directly related to test execution, is focused on improving package installation speed by leveraging caching and parallelization.

Jest vs Yarn

Overview