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How to Integrate Jest Into Your Testing Workflow for Improved Productivity and Reliability

There are numerous challenges that software developers have to face to ensure the reliability of their code. Code quality is something every developer strives for, and testing is a way to ensure that the code performs as expected. Testing helps developers achieve high satisfaction with the product they have created.

Manual testing and unit testing are both equally essential to make reliable software. Numerous frameworks help perform unit testing, and Jest is one such platform designed by Facebook and used for testing both JavaScript front-end and back-end applications.

This blog contains all the information about Jest, its installation, and its configuration. We will discuss the reasons for using the Jest framework for Selenium testing and the different ways to make it faster and more effective.

What is Jest?

Jest is a popular JavaScript testing framework that makes writing and running tests for your code easy. It is an open-source platform with a user-friendly design and requires almost zero effort to set up.

Jest provides an assertion library, a built-in mocking library, and a test runner. It offers snapshot testing. It works with React and React Native-based web applications. Furthermore, it is widely preferred for automated browser testing and can validate the browser rendering of web applications.

Reasons to use Jest Framework for Selenium Testing

Speed and Performance: The speed of the Jest framework is very fast when executing test cases. The overall speed of the test is increased and offers excellent efficiency in the watch mode. Jest has intelligent test execution and can run multiple tests at a time. The platform only runs those necessary tests, so a lot of time and resources are saved.

Added Features and Configuration: Jest provides numerous features and configurations like snapshot testing, mocking, and parallel testing. It can generate code coverage reports and customizes the testing environment to suit your needs.
It allows you to mock dependencies and re-run tests whenever the developer makes any changes. Furthermore, it makes your code consistent by quickly catching regressions and running tests in parallel for large codebases.

Pre-commit hooks: Pre-commit hooks are a powerful feature of the Jest framework that ensures the code is clean and bug-free. Pre-commit hooks are used to improve code quality by running tests before committing. It saves time by automatically running tests and also enhances collaboration between developers. This feature of Jest reduces the risk of breaking existing functionality to remove the bugs from the code.

Easy to migrate: Migrating features is an easy task in the Jest framework for numerous valid reasons. It enhances code quality, reduces the risk of errors, and is super flexible. This easy-to-migrate feature of Jest allows developers to quickly adapt to the changes in the project environment.

To migrate, you need to:

Identify the feature to be migrated.
Check for compatibility issues.
Update the Jest configuration.
Update test code.
Run tests
Address any issues.
Test thoroughly.

Complete package: Jest provides a collection of features or plugins that work together to ensure the testing process is easy and efficient. It provides a built-in test runner, assertion library, mocking library, code coverage, snapshot testing, and integration with other tools.

Basic Setup of Jest Framework

Developers can use additional libraries like WebDriverIO, Selenium WebDriver, or Puppeteer for proper Selenium testing in the Jest framework. If you are using WebdriverIO in Jest, these are the steps you should follow.

Step 1: Install Jest and WebdriverIO using npm or yarn.

Step 2: Create a test case file. The Jest configuration file and a test file should be in the same directory.

Step 3: A configuration file for WebdriverIO should be made afterward. In that file, add essential things like the URL of the website that needs to be tested and the browser used to do so.

Step 4: Once all the technical formalities are conducted, write a test case using WebDriverIO commands. This way, the developers will be able to interact with the website and make necessary changes.

Step 5: Now, it’s time to run the test. For that, you need to use the Jest commands.

Installing Jest Framework

Installing and configuring the Jest Framework requires following the steps mentioned below. You need to write several commands step by step to set up the Jest framework in your system.

There are two ways to install Jest in your system. The first is through npm, and the second is through yarn.

To install it using npm, you need to write the following command “npm install -g Jest”

To install using yarn, write “yarn global add Jest” on your screen.

Once Jest is installed, it’s time to create a test file to write the tests.

Now, use the Jest testing functions like “test” and “expect” to write a test case in the file you just created.

It’s time to run the tests using the “npx Jest” command.

The next step is to configure it. Jest can be configured by specifying the test environment or setting up code coverage.

“Jest.config.js” is used to create a file in the root of the project directory. Then the desired configurations are added to it.

Ways to Integrate Jest With Selenium WebDriver

Below are three different ways to integrate Jest with Selenium WebDriver.

Use Page Object Model Pattern: It is a design pattern used to improve code maintainability and reduce code duplication. Here, a separate class is used to represent each page of the application. The class expresses the essential features of the page elements and interactions. This pattern is helpful because it makes the code more readable and maintainable.

Asynchronous code: The use of asynchronous code is highly recommended because it allows multiple tasks to be executed concurrently. It is better at error handling because it makes debugging and fixing issues easier.
“async/await” syntax is used to make the code more readable and easy to understand. Here, you can separate components into functions and modules.

Standalone Test Runner: Mocha and jasmine are some standalone test runners with built-in support to run your Selenium WebDriver tests. The Jest assertion library can be used to write your tests.

Ways to make your Jest 10X faster

There are various ways to improve our system's Jest performance. Every method mentioned here may work for you. It’s completely fine if that’s the case. You just have to find the one that suits your configuration the best and stick with it.

Switch to yarn+ Node V16+ Jest28.

You can upgrade your Jest to 28 because it has had a lot of improvements. The upgraded Jest is more advanced and provides new exciting features as well. The same can be done with Node.js as well. The first thing you have to do is upgrade everything. It is the easiest way to make your Jest 10X faster.

Fix Slow test cases.

Another thing to do is fix slow test cases. This can be done by optimizing your tests and clearing out the bugs or unnecessary code lines that can make the tests slower. There is a chance that your slower test cases are taking more than 80% of your execution time.

You can write this command “Jest-slow-test-reporter” to identify the slower tests. Once you have identified the problem, you can work on it and resolve it. The execution time of the slowest test cases is a max of 300 ms. Normal test cases are 100 ms; anything more than 300 ms is a red flag.

Memory leaks

It is one of the reasons why your test cases are taking so much time to execute. Memory leaks while executing test cases are a serious issue that is ignored most of the time.

React Testing Library

How you write test cases also plays an essential role in deciding the execution time. Your tests can be slow because you need to use the correct selectors. Stop using “.type” everywhere. You should only use it when required; in other cases, you can fall back to “.paste.”

Switch to SWC/Jest for incredible performance boosts.

In this competitive world, everyone needs a testing framework that is fast and easy to use. That is why it is significant to switch to SWC/Jest. SWC is an ultra-fast compiler written in rust to speed up the development environment. After using this, you can see an immediate improvement in the performance of your code.

Conclusion

Integrating Jest into your testing workflow can significantly improve the productivity and reliability of your software development process. Jest provides a simple API for writing tests, and it comes with many valuable features like test suites, test runners, and test matches. By writing tests with Jest, you can catch bugs and errors early in the development process, saving you time and resources in the long run.

To integrate Jest into your testing workflow, you need to install it using npm, write your tests using the Jest API, and run your tests using the Jest test runner. Additionally, you can integrate and perform your Jest tests with other tools or platforms, like LambdaTest, to further enhance your testing capabilities.

LambdaTest is a cloud-based digital experience testing platform that enables you to perform Jest tests on an online cloud grid at a scale by executing them across more than 3000+ browsers and OS. It allows you to test your application parallely on multiple environments to reduce the test execution time. With LambdaTest, developers and testers can import the automation test cases from various frameworks like Selenium, Cypress, and Playwright.

Overall, Jest is a powerful and flexible testing framework that can help you confidently build high-quality software. Integrating Jest into your testing workflow ensures your code is reliable, maintainable, and bug-free.