JavaScript unit testing is a method of testing that combines the JavaScript test code for websites pages & applications with HTML as a built-in event handler and executes them in the browser to test whether all functions are working properly. Then organize these unit tests into a series of tests.

Each series contains many tests to be run in separate modules. Essentially, they will not overlap with other modules and will be less dependent on each other (in some emergencies, there may be dependencies).

Unit testing helps to reactivate and guarantee code quality. When running tests to verify application behavior or writing tests to verify that errors have been fixed programmatically, it is much easier to update the code reliably. In this article, we will talk about the advantages of unit testing, its challenges, and the best frameworks to use.

Benefits of unit testing

Increase Process Agility

One of the main advantages of unit testing is the ability to increase the agility of the coding process. As you add more functions to the software, modifying the old design and code is sometimes necessary. However, it is dangerous and expensive to change the code that has already been tested. When we have unit tests, we can refactor with confidence.

In fact, unit tests are closely related to all styles of agile programming because they are integrated into the test and allow you to make changes more easily. That is, unit tests help with safe reactivation.

Quality of Code

Unit tests enhance the code quality. It identifies any errors that may occur before additional code is sent to the integration test. If the tests are written before the actual coding is done, you must think carefully about the issue. It reveals boundary scenarios and allows you to write quality code.

Finding Software Bugs becomes easier

Problems are found without wasting time. Because developers carry out units test to test individual code before it is integrated, issues can be identified very early and fixed immediately, without affecting other parts of the code. This includes programmer implementation errors and defects or missing parts of the device specification.

Facilitates Changes and Simplifies Integration

Unit testing enables the programmer to perform code refactoring or update the system library later and ensure that the module is still working properly. Unit testing identifies changes that may alter the design contract. They help maintain and change the code.

Unit testing reduces errors in newly developed functions or reduces errors when existing functions are changed.

Troubleshooting Process

Unit tests help streamline the process of troubleshooting the code. If the test fails, all you have to do is troubleshoot the latest code changes.

Challenges of JavaScript Unit Testing

• While using the unit testing, you will need to write more codes than before. Generally, you have to write one or more unit tests, depending on the complexities of things. It is recommended that you have a minimum of three, so you wouldn’t end up with a yes and no contradiction. While the test code should be simple enough, this test method still requires more work and code, which means more time and higher costs.
• When you need to test the user interface (UI), there are always problems with the unit testing. They're great when you need to test business logic, but they're not great for user interfaces.
• There is a belief that unit tests have more problems with the structural design of products. They help make code structure more solid, meaning there might be issues when they need to be changed.
• Compared to those who claim unit testing helps code quality, others say it worsens it and ultimately makes it pointless. Changing and adding new code might result in navigational issues and extra time before running integration tests.

Best frameworks for JavaScript Unit Testing

Jest

Jest is a JavaScript testing framework that works as a parallel test with zero configuration, with functions like snapshots, making it easy to maintain large diffs. Jest is managed by Facebook and was initially linked to ReactJS testing. Jest has many built-in features, not just for React but also for Vue, Angular, Node.js, TypeScript, and many other projects.

Jasmine

Jasmine is the behavior-based development framework for performing JavaScript unit testing. It is used to test synchronous and asynchronous JavaScript code. There is no need for DOM, and it has a simple syntax that can be written for a different test.

Unit.Js

It is called an open-source authentication library that runs on the browser and Node.js. It is highly compatible with other JavaScript unit testing frameworks, such as Mocha, Karma, Jasmine, QUnit, Protractor, etc. Provides a complete documented API for the checklist

Cypress

Cypress is very common with testers and developers as it does not need configuration. The framework can be executed on the browser, where it offers an interactive interface. Additionally, Cypress is usable on Mac, Linux, and Windows. Cypress tester can also automatically capture screenshots and videos.

In general, react developers love using Cypress. However, Cypress supports other JS frameworks, like Angular and Node.js. Testers often compare Cypress to selenium. However, the main difference between the two is that Cypress does not need to be included in your code.

AVA

AVA is an excellent test library for Node.js. The test library has been very popular because it offers process isolation. This means that each test file is run separately in the Node.js process. Being able to trust your test results is an important quality. There is no interference between different test scenarios. Also, the tests end much faster because they run simultaneously.

Mocha

Mocha also runs on Node.js through the browser. Mocha carries out asynchronous testing in a less complicated way. It offers reporting accuracy and flexibility. Good support for a wide range of features like specific test expiry time, JavaScript API, etc.

Karma

Karma is a powerful open-source testing environment. Simple control of the workflow is performed from the command line. Provides the freedom to write tests using Jasmine, Mocha, and QUnit. You can perform tests on real devices by simple troubleshooting.

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