A little introduction to JS unit testing and its framework and tools
Importance of Unit testing
Before we get into understanding the available tools and their benefits, let us understand why unit testing is important.
Unit testing is the process of testing the implemented code at a module level. Unit testing allows you to ensure that your developed modules are meeting the requirements specified by the business document. These tests are written for every module as they are created. After every new module development, the entire suite of test cases is run to ensure that no existing modules are affected by the developed module.
These tests focus on testing the usability and responsiveness of the application. The backend unit testing frameworks focus on testing business logic and service endpoints for NodeJS based backend code.
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 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
Check out this brilliant unit testing with Jasmine online course.
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
- Cleaner stack traces for any potential errors that are detected
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 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 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 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 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 works with Node, browser, rail and got great support community and documentation.
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.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
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. If you are a newbie, then you may like this online course which teaches you doing JS unit testing with ChaiJS, Sinon and Mocha.