Overview

Mocha

Stacks10.8K

Followers3.0K

Votes430

Chai

Stacks5.4K

Followers196

Votes0

GitHub Stars8.3K

Forks707

Chai vs Mocha: What are the differences?

Chai and Mocha are both popular JavaScript testing frameworks. Here are the key differences between the two frameworks.

Assertion Styles: Chai provides multiple assertion styles, including should, expect, and assert, allowing developers to choose their preferred style. In contrast, Mocha does not have built-in assertion libraries and requires developers to use external libraries like Chai or the Node.js built-in assert module for assertions.
Test Runner vs Assertion Library: Mocha acts as a test runner and provides a testing framework with features like test suites, hooks, and reporters, while Chai is primarily an assertion library and focuses on providing expressive syntax for assertions. Chai can be used with any test runner, including Mocha, to enhance the assertion capabilities.
Synchronous vs Asynchronous Testing: Mocha supports both synchronous and asynchronous testing out of the box. It allows the usage of promises, callbacks, and async/await syntax for handling asynchronous code. Chai, on the other hand, is agnostic to asynchronous testing and can be used in both synchronous and asynchronous contexts.
Extendability and Customizability: Mocha offers a wide range of plugins and customizations, allowing developers to extend its functionality and customize the test runner behavior. Chai, being an assertion library, focuses more on providing flexible and customizable assertion syntax rather than extensive customization of the testing framework itself.
Chaining and Readability: Chai provides chaining methods like to, be, and have, which enable developers to create readable, expressive assertions. These chains can be nested to create complex assertions. Mocha, being a test runner, does not provide this level of chaining and readability, as its main focus is on managing the test suites and generating test reports.
Community and Documentation: Both Chai and Mocha have active communities, but Mocha has a larger user base due to its versatility as a test runner. Mocha also has comprehensive documentation, including examples and guides, making it relatively easier for developers to get started and find support.

In summary, Chai provides different assertion styles, while Mocha acts as a versatile test runner with support for synchronous and asynchronous testing. Chai focuses on providing expressive syntax and customizable assertions, whereas Mocha offers extensive customization options for the testing framework itself.

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Advice on Mocha, Chai

Abigail

Dec 10, 2019

Decided

We use Mocha for our FDA verification testing. It's integrated into Meteor, our upstream web application framework. We like how battle tested it is, its' syntax, its' options of reporters, and countless other features. Most everybody can agree on mocha, and that gets us half-way through our FDA verification and validation (V&V) testing strategy.

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Detailed Comparison

Mocha	Chai
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.	It is a BDD / TDD assertion library for node and the browser that can be delightfully paired with any javascript testing framework. It has several interfaces that allow the developer to choose the most comfortable. The chain-capable BDD styles provide an expressive language & readable style, while the TDD assert style provides a more classical feel.
browser support;simple async support, including promises;test coverage reporting;string diff support;javascript API for running tests;proper exit status for CI support etc;auto-detects and disables coloring for non-ttys;maps uncaught exceptions to the correct test case;async test timeout support;test-specific timeouts;growl notification support;reports test durations;highlights slow tests;file watcher support;global variable leak detection	-
Statistics
GitHub Stars -	GitHub Stars 8.3K
GitHub Forks -	GitHub Forks 707
Stacks 10.8K	Stacks 5.4K
Followers 3.0K	Followers 196
Votes 430	Votes 0
Pros & Cons
Pros 137 Open source 102 Simple 81 Promise support 48 Flexible 29 Easy to add support for Generators Cons 3 Cannot test a promisified functions without assertion 2 No assertion count in results 1 Not as many reporter options as Jest	No community feedback yet

What are some alternatives to Mocha, Chai?

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.

Jest

Jest provides you with multiple layers on top of Jasmine.

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.

QUnit

QUnit is a powerful, easy-to-use JavaScript unit testing framework. It's used by the jQuery, jQuery UI and jQuery Mobile projects and is capable of testing any generic JavaScript code, including itself!