I think you are already familiar with testing, and you came here to know about the testing libraries for your React application. If that’s the case, then you are in the right place. Before we look into different types of libraries, let’s quickly see how testing affects your application quality and development time.
Testing Effect
Some of you may feel that writing tests for the application are a time taking process. Let’s skip this for now. No, it’s not a time-wasting thing to write the tests for your application. Let’s say you have developed an application that doesn’t have any tests. It has featured more than 100 functionality. After a considerable amount of time, say 3 months. Your clients want you to add 5 new features and tweak 2 features from the 100 features you have developed before. You don’t have any problem with it and completed all of them and shipped your code to production (without tests as usual). After some days, your client came to you again saying that the old features are breaking. And you didn’t understand why? Again you spent a considerable amount of time resolving the issues. After the completion of resolving the issues, you started losing confidence. How to gain that confidence? And save that extra time you spent on resolving the issues. One thing will do all things right, i.e.., testing. Let’s assume you have written tests for your application. You will run tests again when you have developed new features or tweaked old features. In that case, you will get to know about the issues before going to the product itself. It saves a lot of time and makes you confident about the quality of your application. Now, it’s time to look into different testing libraries for your next React project.
Testing Library
Testing Library is a group of packages that helps you test the UI components. Our focus is on the React Testing Libray. The react testing library is a lightweight library with a complete set of utilities for the testing of React DOM. It allows us to test the react components without giving the library’s implementation details. It helps us to gain more confidence by making testing easier. Most of the time, it works along with the Jest testing library. It offers simple methods and utilities for testing and guides us to follow the best practices in testing. Some of the features of react testing library are:
It doesn’t care about the testing of the internal state of the components.Testing the render result of the components.Tests the DOM nodes instead of the instances of the classes.It provides a custom way to access the DOM elements in the library.Makes sure that the UI is working properly.It has large community support.
Jest
Jest is a testing framework to test JavaScript and TypeScript code. And it integrates with the front-end libraries well. It is developed and maintained by Facebook. React team recommends it for the testing of the React application. It has the most downloads than all other testing libraries around. Jest, along with the react testing library, will be more powerful for React testing. And most developers out there are using this combination for their testing. Some of the features of the Jest are:
Tests are isolated from one another.It provides code coverage.It’s fast.It provides a way to mock the functions.It offers different kinds of exceptions for testing.
Enzyme
The enzyme is a testing utility for the testing of React components. It allows us to traverse and easily manipulate the React component rendered output. It was created by Airbnb. It has to be used with the other test runners like jest, mocha, jasmine, etc.., for the testing of React components. It provides additional and easy ways to render and test the React components. And it only works with the React library.
Mocha
Mocha is a testing framework making the testing simple. It runs on NodeJS. Its test runner work along with other testing libraries for React testing. Some of the features of the Mocha are:
Provides test coverage reports.Completely configurable with the config file.Async test timeout support.Timeouts based on the tests.It even highlights the slow tests for you.
Mocha has a lot of other features waiting for you on its home page.
Karma
Karma is a testing environment for your application. It allows us to run tests on real browsers and devices (mobiles, tablets, and desktops). It aims to provide different environments to the developers for testing. Some of the features of Karma are:
Test your code on real devices.It allows us to test our code on a headless environment like PhantomJS.You can integrate Karma with CI/CD tools like Jenkins, Travis, and Semaphore.You can easily integrate it with other test frameworks like Mocha, Jasmine, etc..,Debugging is made easy with the IDE.
Jasmine
Jasmine is a Behaviour-Driven Development (BDD) testing framework for JavaScript. It doesn’t require DOM for testing the code. Jasmine is designed for the testing of NodeJS code. We can test React with Jasmine and other testing libraries. Some of its features of Jasmine are:
It has clean and easy syntax for writing tests.We can write tests for both the front end and backend.The core of jasmine doesn’t have any dependencies, which makes it fast.
Chai
Chai is an assertion library. It can be paired with any other JavaScript testing library. Chai provides functionalities like should, assert, and except for assertion.
Cypress
Cypress is the JavaScript end-to-end testing framework. It allows us to set up, write, run and debug tests in the browser. It has a dashboard that gives you a detailed report on the status of each test you write. Cypress runs the test in an actual browser environment which gives you access to the dev tools as well. It’s used to test the end-to-end flow of a feature in the application. Some of the features of the Cypress are:
You can see the snapshot of every step. It takes snapshots of each step while running the tests.It made debugging easy with DevTools.Cypress automatically reruns the tests when you make changes to the tests similar to the React real-time feature.The tests will automatically wait for the output without using the await statement.
Conclusion
Writing tests is good for you and the application. It makes things easy in hard times. Don’t make an excuse in it. The order of the testing libraries in the articles doesn’t have any importance. It’s just for the count. No library is lower than others. Each library has its own advantages and disadvantages. We can mostly test the complete features of the React application using React Testing Library and Jest. And it’s recommended by most of the React community members. It’s not mandatory thing for you to use those two. If you are a beginner, then you can give it a try. If you are looking for something more specific for your React application, then go through each library. Happy Testing 🙂
