How to Perform Jest Testing on LambdaTest

Last Updated:
September 19, 2023
Kay Nicole

How to Perform Jest Testing on LambdaTest

Jest is one of the most popular JavaScript testing frameworks built by Meta (Facebook). It is an open-source testing framework designed to test React and React Native-based web applications. It has a built-in test runner that makes it easy to use by automatically finding and running tests. Jest also provides a simple and intuitive API for test cases.

When it comes to testing web applications, integrating Jest with LambdaTest can greatly enhance the testing process. Jest, a testing framework, simplifies testing, while LambdaTest, a cloud platform, lets you test on various setups. They are a dynamic duo that works together to make sure your app works smoothly across browsers and devices.

This blog contains all the information that you need to know about Jest testing on LambdaTest. We will start by discussing what is Jest testing, its benefits, an overview of the LambdaTest cross-browser testing platform, and steps to set up jest testing on LambdaTest.

So without any further ado, let’s start with the basics.

What is Jest testing?

Unlike any other testing platform, Jest also ensures that the application works as expected and doesn’t break when you make any changes or updates. This framework is known to reduce a lot of complexities for the testers. It validates almost everything around JavaScript, especially the browser rendering of your web applications.

Jest's user-friendly nature makes testing enjoyable and efficient. It also provides valuable insights to increase software reliability, making it easy and effortless to use.

It does not rely on third-party applications and software. This feature is one of the reasons for its huge public demand. Jest can perform both unit testing and component testing with ease. It has an excellent package of assertion library, test runner, and built-in mocking library.

Jest offers a comprehensive and developer-friendly testing solution, making it a popular choice for writing tests in JavaScript and TypeScript applications.

Understanding The Benefits of Jest Testing 

Jest offers a wide range of benefits. It has some advantages over other platforms that make it one of the most popular testing frameworks ever. Let’s explore why you should use Jest for automation testing.

1. Easy to use

Setting up a Jest testing environment does not require you to learn a lot of things. Jest is known for its simple and easy-to-use syntax. It makes it easy for developers to write and structure tests. Its developer-friendly API makes it accessible for both beginners and experienced developers. Jest was created with simplicity in mind. That is why it makes it easy for developers to write and execute tests effectively. 

2. It can automatically execute code

Jest comes with a built-in test runner that can automatically find and execute tests. This automation saves time and effort for developers, especially when dealing with large codebases and numerous test cases. This automation simplifies the testing process and ensures your code is robust and dependable.

3. Effective use of Snapshot Testing

Snapshot testing in Jest is like taking a picture of how your website or app looks and works when it's working just the way you want it to. It is a feature that allows you to capture the "snapshot" or the current output of a component or piece of code during a test run.

Later, when you make changes to your code, Jest compares the new look with the snapshot you took. If things don't match, Jest tells you that something might be off, helping you catch unexpected changes easily.

4. Has a wide range of built-in matchers and expectations

Think of matchers like a set of rules. They help you check if things in your code are correct or not.  Each rule (matcher) has a specific job, like checking if two things are the same or if something is empty. Jest uses these rules to make sure your code works how we expect it to.

Matchers and expectations are fundamental features that help you define the expected behavior of your code and make assertions in your tests. 

5. Offers robust mocking and spying capabilities

Mocking helps create pretend versions of complex parts. Due to this, developers can test without complications. Spying allows developers and testers to secretly watch and gather information about how certain functions are used during tests. These features make testing code much easier and more accurate.

Overview of LambdaTest

LambdaTest, AI powered test orchestration and execution platform that helps developers and testers ensure their websites or applications work smoothly on a wide array of devices and browsers. It offers a cloud-based testing environment. You can upload your website or app to their platform and choose from a variety of real devices and browsers.

You can then interact with your website or app just like a real user would. LambdaTest saves both time and effort. Instead of manually checking your website or app on each type of device and browser, LambdaTest automates this process.

The platform supports real-time testing. It allows users to interact with the application in real-time across different browsers and devices. This feature is valuable for identifying and resolving issues quickly. Furthermore, it supports all major platforms like Selenium, Playwright, Cypress and many more.

LambdaTest helps to see if a website or app is fast and works well. If there are any problems, it helps to find and fix them, making sure the website or app works faster and better for people using it.

It is a powerful tool for ensuring your website or app is a star performer on any digital runway.

How To Set up Jest Framework for LambdaTest

Setting up Jest testing for LambdaTest involves integrating Jest with LambdaTest. This integration allows you to automate and streamline your testing process across various browsers and devices. Here's a step-by-step guide to help you set up Jest testing for LambdaTest:

1. Installation of Jest and LambdaTest packages. 

First things first, you will install the Jest framework and any necessary packages using npm (Node Package Manager) or yarn, a popular package manager. To integrate LambdaTest with Jest, you need to install the LambdaTest package as a Jest test runner. Once installed, Jest provides an environment where you can write and run various types of tests to ensure the correctness of your code.

2. Set Up the Environment for Effortless Testing

Start by creating a file named jest.config.js in your project. Here, you'll define how Jest should operate and what it should consider during testing. Specify the directories or files where your tests reside. It will highlight the specific area you want to focus on in your workspace.

After that, set up some rules. Every project has its rules. Jest allows you to create rules for your tests, like how they should run and what constitutes a successful test. You can also customize the environment according to your needs. Jest is flexible. You can change its behavior based on your project requirements.

3. Writer Test Cases 

Begin by describing the area you want to test, like a specific function or a component, using describe(). Create individual tests inside each section using test() or it(). Within each test, you use assertions (functions like expect()) to check if the actual behavior matches the expected behavior. If you have multiple tests with a similar setup, you can group them together using beforeEach() or beforeALL() for better organization.

Writing test cases in Jest Involves breaking down your code into manageable sections, defining expected behaviors, and verifying those behaviors to ensure the functionality of your application.

4. Run Test Cases

To run all your tests, execute the command npx jest in your terminal. Jest will automatically discover and run all files with test cases in your project. If you want to run specific test files or match a pattern, you can provide a path or pattern after the npx jest command. You can also use npx jest --watch to run tests and automatically re-run them when files change.

By running all or specific tests, watching for changes, and examining coverage, you ensure the reliability and robustness of your application. Just as quality checks are a critical part of any professional process, running tests in Jest is fundamental to delivering high-quality code.

Best Practices for Jest Testing on LambdaTest 

Implementing best practices for Jest testing on LambdaTest is vital for reliable testing. It ensures accurate results, faster testing cycles, and efficient detection of compatibility issues across browsers and devices. Embracing these best practices creates an environment of continuous improvement. Which further leads to higher-quality applications and enhanced user satisfaction.

1. Validate your Application across various environments through optimized browser diversity 

Use browsers and devices that are easily accessible to your target audience. Consider popular browsers e.g., Chrome, Firefox, Safari, and various device types like desktop, mobile, and tablets.

Then, set up Jest to run your tests on these browsers using LambdaTest. Create tests that check how your website works on each browser. After running the tests, look at the results to see if everything's working as expected. If there are issues, adjust your tests accordingly. This way, you ensure your website works well for everyone, no matter what browser or device they're using.

2. Organize Jest tests into logical and efficient test suites

Organizing Jest tests into logical and efficient test suites means categorizing your tests according to your needs. It's like sorting your books on a bookshelf. Putting novels together, textbooks together, and so on.

In Jest, this means grouping tests based on what they check. For example, tests for login functionality go in one group, while tests for search features go in another. This logical grouping makes it easier to find and manage tests, just as sorting books helps you quickly find the one you want. It's about maintaining order and simplicity in your testing process.

3. Implement thorough error-handling strategies to effectively manage failures and exceptions within your tests. 

Implementing good error handling in Jest testing is like having a backup plan when things don't go as expected. Errors are unexpected and can happen anytime. In Jest, when a test fails, you need a plan to understand why. You might add helpful messages or comments to your tests to know where the issue is.

Clear error messages will help you quickly spot what went wrong in a test. It's about being prepared and having ways to solve obstacles in your testing journey.

4. Use Jest's capabilities to selectively run tests and save both time and resources. 

This practice allows you to run specific tests related to the features you're working on. Simply put, the tester/developer will only focus on things that need specific attention. This helps save time and resources so that you're testing precisely what needs to be fixed or improved in any way.

It's about efficiency and focusing your efforts where they matter most. This way, you will not waste your time fixing something that’s not so vital at the moment. Selective test execution is all about optimizing the testing process for both developers and testers.

5. Continuously review and update your Jest tests 

With time, you need to revisit and improve your tests as your app changes. It’s no rocket science. All you have to do is constantly review your work. By doing so, you are making sure the changes in the app do not affect other areas in any way.

Developers don’t create an app once and then forget about it. It doesn’t work like this. Constant reviewing and refinements are always needed. This practice ensures your tests are always relevant and contribute to the overall reliability of the application.


Using Jest with LambdaTest is like teaming up two powerful tools to ensure your website works perfectly. Jest helps check different parts of your website to make sure they function correctly. LambdaTest takes this a step further by allowing you to test your website on various devices and browsers.

It's like having a reliable team that not only checks but also helps improve your website's performance, making sure it runs smoothly for everyone. When your website passes these tests, it's ready to impress users and give them a great experience. Jest with LambdaTest is a winning combo that guarantees your website is top-notch and user-friendly in today's digital world.

© 2019-2023 Mike Gingerich Global, LLC    Contact   -   Privacy

magnifiermenu linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram