11 Best JavaScript Unit Testing Framework and Tools

Over the last few years, the web development coding scenario has changed at an exponential rate. The world has moved on from traditional programming languages such as Java,.NET, and PHP. They have begun to adapt to the JavaScript framework due to its ease of use in both the frontend and backend, as well as its rapid prototyping capabilities.

This transition necessitates the use of high-quality testing tools. In this article, I'll walk you through some of the industry's best javascript unit testing tools.

Importance of Unit testing

Before we get into the available tools and their advantages, let us first understand why unit testing is important.

The process of testing implemented code at the module level is known as unit testing. Unit testing allows you to ensure that the modules you've created meet the requirements outlined in the business document. These tests are written for each module as it is built. Following the development of a new module, the entire suite of test cases is run to ensure that the developed module has no effect on any existing modules.

If the proper conventions are not followed, Javascript development can become quite disorganised. This necessitates the use of appropriate development and unit testing tools. Frontend Javascript unit tests are mostly run on real or headless browsers.

These tests are designed to evaluate the application's usability and responsiveness. Backend unit testing frameworks are designed to test business logic and service endpoints in NodeJS-based backend code.

MochaJS

MochaJS is the most popular testing framework that supports backend and frontend testing. MochaJS is a flexible base for developing tests as you need. It runs the tests asynchronously on Chrome v8 engine or any other browser.

The major benefits of Mocha include:

• Works for frontend as well as backend
• Support NodeJS debugger
• Provides a clean base to develop tests as per the developer’s convenience
• Supports any browser including headless chrome library
• Supports object mocking to perform flexible backend tests

Jasmine

Jasmine is a user-behavior mimicker that allows you to perform test cases similar to user behavior on your website. Jasmine is useful for a testing frontend for visibility, click clarity as well as the responsiveness of the UI in different resolutions. Jasmine allows to automate user behavior with customs delays and wait time to simulate actual user behavior.

The major benefits of using Jasmine include:

• Lower overhead due to almost zero external dependencies
• Comes with almost every required tool out of the box
• Supports Frontend as well as Backend tests
• The coding is pretty similar to writing in natural language
• Extensive documentation to use it with several frameworks

AVA

AVA is a minimalistic light-weight testing framework that leverages asynchronous nature of Javascript. AVA can perform tests concurrently.

It allows you almost complete control over what you do. It is primarily focused on running tests for NodeJS based code. Some of the benefits include:

• Light footprint makes it faster
• Runs tests asynchronously and concurrently
• Faster than most other test frameworks
• The simpler syntax for Javascript tests
• Cleaner stack traces for any potential errors that are detected

JEST

JEST is one of the most popular frameworks that is maintained regularly by Facebook. It is a preferred framework for the React based applications as it requires zero configuration.

However, it is not limited to use with React. Some of the JEST features are:

• Single framework fit for NodeJS, VueJS, React, Angular and other Babel based projects
• Easier to get off the ground
• Well documentation and standard syntax of coding
• With Live snapshots, it allows managing tests with larger objects

Karma

Karma is a productive testing environment that supports all the popular test description framework within itself. It provides your application the support to execute tests in different environments. It has wide support for executing tests on different devices and applications.

The primary factor to choose Karma lies in its support to integrate with CI/CD engines and the following features.

• Can be used to run tests on browsers, headless environments like PhantomJS as well as on devices
• Supports tests written in most of the popular frameworks
• Allows to run tests remotely onto other devices by just coming files
• Supports test case debugging using Chrome as well as Webstorm

Tape

Tape is pretty similar to AVA in its architecture. It does not support globals, and hence you need to include Tape in each test file. This decision of restricting globbing of variables has its benefits too. Some of the features highlight:

• Clean light-weight footprint
• Provides just bare-metal code and gives the developer complete freedom to write test cases
• Supports ES6, Typescript and coffee script standards
• Supports test execution on most modern browsers

Cypress.io

Cypress is an exciting testing framework that practically runs on the browser. It provides an interactive UI on the browser in the form of a web page. It can be easily installed on Mac, Windows as well as Linux. It is an independent test runner that does not need to integrate with your code closely.

Puppeteer

Puppeteer is an excellent test execution framework built by a team at Google. It provides a headless chrome API for NodeJS applications.

Puppeteer is primarily used for applications specific to the browser like crawl test, page structure test, take screenshots and even capture pre-rendered content for single page applications. Additional benefits of using puppeteer are:

• Ability to set custom resolutions and sizes for the browser
• Support to test chrome extensions
• Automation support for form submission, UI testing, and keyboard inputs
• Supports ES6 functionalities like await and async

ChaiJS

ChaiJS framework focuses on behavior-driven testing. It can be used in parallel with any other framework. It has been around for quite a while now and has evolved with the evolution in Javascript standards.

ChaiJS works with Node, browser, rail and got great support community and documentation.

Qunit

Qunit – a powerful testing framework dedicated to using with a frontend. It is the first choice by developers of the JQuery, JQuery Mobile and JQuery UI libraries.

It can be written as an independent JS file and executed on any webpage. The standard method of testing using Qunit is to include the file onto the webpage and run tests using Qunit plugin. The benefits of QUnit include:

• Can be used to build re-usable test scripts
• Provides a ready-to-deploy web interface for viewing test case outputs visually
• A pool of plugins built on top of it allows faster test case development

Sinon

Sinon.js compliments the unit testing framework to fake/mock the real things. Because during testing – you won’t have all the data! It supports Chrome, IE 11, Firefox, Edge, Safari and Node.js runtimes.

A good alternative to Sinon would be testdouble.js

Conclusion

Unit testing is essential to ensure code changes doesn’t break the application, and it works as per business requirement. And, I hope above helps you with that.