We all know the love of developers for the most popular library React. It’s easy to learn and it’s easy to build the user interface of any website using React. If you’re building an application no matter what you should test your application before serving it to the user.
If you are a frontend developer working on the React library, you might have some favorite tool or framework for testing your React application. A lot of developers use Jest, Enzyme, or some other popular tools and libraries to test the components of React application. However, every tool or framework is not the same for everyone. There are tons of testing frameworks and tools available in the open-source ecosystem for testing purpose of React application.
Whether you’re doing unit testing, integration testing, or end to end testing, choosing the right toolset and framework for testing is the key factor in leveraging TDD in React. In this blog let’s talk about some popular React testing frameworks and libraries which a lot of people use in their day to day job.
- Very fast performance. Airbnb saw a decrease in the total test runtime from 12 minutes to only 4.5 minutes when they switched from Mocha to Jest.
- It conduct snapshot, parallelization, and async method tests.
- Mock your functions, including third-party node_module libraries
- Possible to manage tests with larger objects using live snapshots.
- Standard syntax with report guide.
- Compatible with React, VueJS, Angular and many projects.
- Runs on Node.js and provides support for asynchronous front-end and back-end testing
- Helps in error tracking.
- Combination of Mocha with Enzyme and Chai is popular for the assertion, mocking, etc. Enzyme + Mocha is a good combination to test web applications written in ReactJS.
- A document object model (DOM) is not required for Jasmine.
- Helpful in both the front and back end tests.
- Async function tests.
- Mocking requests.
- Custom equality checker assertion.
- Custom matcher assertion.
- Solid documents and community support.
Keep in mind that Jasmine doesn’t support snapshot tests, code coverage tools, parallelization (requires third-party tools), and native DOM manipulation (requires a third-party tool).
Enzyme is a testing utility designed to help developers for testing the React component without any hassle. Enzyme is one of the most used frameworks developed and maintained by Airbnb. Developers combine it with other frameworks such as Jest, Chai, or Mocha to test the React application. The enzyme is only used to render components, access things, find elements, interacting with elements, and simulate events. Chai or Jest can be used to make the assertions for it. You can test the outputs of React components, abstracting the rendering of components. Read more about testing the React application from the link Enzyme with Jest.
- Use shallow rendering.
- Access business implementations of your components.
- Conduct full DOM rendering.
- Use react-hooks in shallow rendering, with some limitations.
6. Cypress IO
Cypress is a very fast end to end testing framework that enables you to write your tests without any additional testing framework. It allows you to run your tests in the real browser or command line. Along with testing your code in the real browser, you can also use browser development tools side by side. The framework comes with its control panel that gives you control over the status of your tests. Some pros and advantages of using Cypress are…
- Time travel with snapshots
- Screenshots and videos
- Automatic waiting
- Control network traffic without touching your server to test edge cases
- Built-in parallelization and load balancing makes debugging easier.
- Nice API to interact with page components.
React-testing-library is created by Kent C. Dodds and supported by a vast community of developers. It allows you te to test the component easily and simulates the user behavior in your tests. Similar to enzyme this library is a complete set of React DOM testing utilities focused on imitating actual user actions and workflows. Read the article Revisiting React Testing in 2019 to make a choice in between react-testing-library and Enzyme. You can do the following things with react-testing-library…
- Query your elements within text, label, displayValue, role, and testId
- Fire any event
- Wait for an element to appear with wait
There are some limitations of this library as well as you cannot conduct shallow rendering and you can not access the internal business of your components, such as states.
- Easy automated UI test, form submission, and keyboard input
- Easy creation of screenshots and PDF files of web pages
- Support for testing Chrome extensions.
Puppeteer doesn’t support a large number of extensions, but the future is bright and promising.
We can see that each testing library and framework has its advantage and drawbacks. Whether it’s a unit test, integration test, or end to end test choosing the right tool helps a lot in getting the best result. To test the React components combining the right testing framework (e.g. Jest etc) with the right assertion/manipulation libraries (e.g. Enzyme etc) matters a lot for creating a smooth and flexible workflow, that can adapt while you upgrade, extend and modify your code.