Unit Testing in JavaScript: A Tutorial

It provides an isolated environment for testing components. Stories make it easy to explore a component in all its variations, regardless of its complexity. That means stories are a practical starting point for your UI testing strategy. You already write stories as a natural part of UI development, testing those stories is an easy way to prevent UI bugs over time.

js unit testing framework

Jest can collect code coverage information from entire projects, including untested files. Developed by Google, Puppeteer provides a cool way to unit test your JavaScript components. For Node JS apps, Puppeteer provides a headless application programming interface that you can use in Chrome. If you’re new to the game and need a lot of help getting up to speed, you should choose frameworks with strong communities like Jest. If you require a broad API along with specific features then Mocha is a smart choice, as the extensibility is there.

Unit Testing Framework for JavaScript

If we want to ensure code quality on the client-side, we need to be rigorous on bringing best practices for code quality along. Luckily, there are plenty of well-vetted tools available to do JavaScript Operating System Linux unit testing. A built-in mocking framework that requires minimal boilerplate code (e.g. no$tearDown or $verifyAll) with style and semantics based on the Google C++ Mocking Framework.

Check out this brilliant unit testing with Jasmine online course. The Jest core team and contributors regularly speak about Jest and Delightful JavaScript Testing. Check out our talk about Building High-Quality JavaScript Tools at jsconf.eu 2017 and our talk about Jest as a Platform at ReactiveConf 2017.

js unit testing framework

It is not written specifically for testing and can control a browser for many purposes by using a driver that controls browsers using add-ins and browser extensions. The tools for the purpose of functional testing differ from each other in their IT Help Desk Technician job description template Workable implementation, philosophy, and API. Therefore it is strongly suggested to invest time in understanding the different solutions and testing them on your product. Unexpected is an assertion library with a slightly different syntax from Chai.

Node.js library for comparing images. Contribute to gemini-testing/looks-same development by creating an account on…

Jest builds on the body of work laid by Jasmine, which uses a behavior-driven development taxonomy where you describe a test suite, make it … should (or expect … to) expectations. Surely in one of these frameworks you will find the help you need to develop your next application. Our developers at Rootstack have used some of these to solve technology problems for our customers. Testing frameworks use a set of rules or best practices to automate tests for a piece of code.

js unit testing framework

This way you can run them much faster in terms of performance and even entirely from the command line. Just a couple of years ago website testing had little documentation, was slow, hard to implement, not deterministic, and, generally, not pleasant to work on. A Quality Assurance Director is responsible for ensuring that the products and services a company provides meet certain … Cypress also comes with a test runner that produces automated screenshots and video captures if desired. Jasmine has supported async spec functions and waiting on returned promises for two years now.

Other testing tools

Code integrity refers to achieving the desired outcome as intended by the developer. The results should also be repeatable in every scenario the code or the program is likely to encounter. Testing any program before it goes live is just as important as the underlying code. You can’t afford to release a bug-ridden codebase only to recall it later and suffer immense financial and reputational damages. Understanding JavaScript Design Patterns In Depth Want to reuse pieces of your JS code? Learn about JavaScript design patterns and their benefits.

You have to provide an input that’s supposed to produce a known output. And if the output that comes after testing matches the known output, then your testing Hackathons are for beginners Hackathons sound scary but actually by Tim Fogarty tfogo is successful. Please also note that if a library is new and doesn’t have a strong community at the moment, it doesn’t mean this will always be the case.

  • Puppeteer is a Node library that provides a high-level API.
  • You can pick the ones with active communities like Jest and Jasmine.
  • As an aside, the 2021 version of the survey has been delayed to sometime in 2022, in case you’re wondering.
  • Provide all these units with simple and edge case inputs and make sure outputs are expected using assertion functions.
  • Although the team behind Vitest has done a tremendous job on creating this tool, it’s still young and the community support may not be what you’re hoping for.

These transitions over time also result in the need for excellent testing tools. It has been around for almost two decades, and it continues to be used by millions of front-end and back-end developers all around the world. According to the State of JS survey, Jest was nominated as the best JavaScript unit testing framework for 2020. A significant chunk of the popularity of Jest comes from the fact that it supports a lot of technologies and frameworks. Note that it won’t be an easy task to hit 100% code coverage. Sometimes, you’ll have to invest a lot of time to cover particular lines of code with unit tests.

More than these with upcoming challenges in performing testing there, some more powerful frameworks and tools may get evolved in future. With Jest, you can quickly mock functions or assign a variable a mock function. The framework will provide you a test coverage report that shows what percentage of the code has been tested.

JavaScript is one of the core programming languages powering the World Wide Web. The front-end languages empowers developers to create dynamic web pages. Unit testing is the process of running tests focused on a small section of the entire code to ensure its functionality. Every individual ‘unit’ of the code is tested before moving on to other testing processes.

Although its popularity has recently dropped, Jasmine is still an excellent choice for JavaScript unit testing. Based on the type, programming language, and the identified pros and cons, you must have shortlisted the best frameworks applicable to your project. Carry out initial testing processes and identify what works better for you.


Provide all these units with simple and edge case inputs and make sure outputs are expected using assertion functions. Looking forward, I forecast that AI would become more impactful in the field of automated tests. Some such tools already exist, and actively improving the workflow and experience of thousands of developers. Today’s cutting edge website testing tools are fast, informative, and easy to work with.

The Testing Library family of libraries is a very light-weight solution for testing without all the implementation…

Has some nice integrations like with storybook different CI tools and BrowserStack and Sauce Labs. It hooks into the CI to compare the visual appearance of UI components before and after a change. Cross Browser and Devices- Supports many browsers and devices and can be used with SauceLabs or BrowserStack which provide devices and browsers for your tests. This includes running of tests in Headless Chrome and Headless Firefox which will be discussed later. Notice that this tool doesn’t come with a build-in testing system. Tools like mocha and chai can be used to create the necessary testing environment and structure around this library.