Delightful JavaScript Testing

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Built with accessibility in mind, its approach also makes refactoring a breeze. Mocha is a JavaScript test framework that is focused on being flexible. Because of this flexibility, it allows you to choose different libraries to fulfill other common features such as spying (e.g., Sinon) and assertions (e.g., Chai). Another unique feature of Mocha is that it can also execute tests in the browser in addition to Node.js. Jest is a JavaScript test framework that is focused on simplicity. One of its unique features is the ability to take snapshots of tests in order to provide an alternative means of verifying units of your application.

It provides an isolated environment for testing components. Stories make it easy to explore a component in all its variations, regardless of its complexity. That means stories are a practical starting point for your UI testing strategy. You already write stories as a natural part of UI development, testing those stories is an easy way to prevent UI bugs over time.

What is better than JMeter?

  • Tricentis Neoload.
  • Micro Focus LoadRunner Professional.
  • TestComplete.
  • Katalon Platform.
  • WebLOAD.
  • BlazeMeter Continuous Testing Platform.
  • Postman.

A minimalistic testing runner, AVA takes advantage of JavaScript’s async nature and runs tests concurrently, which, in turn, increases performance. There’s no need for additional assertion or mocking libraries — Jasmine has them all out of the box. Since it doesn’t rely on any external libraries it’s relatively fast. You have to include additional libraries for assertions, and this does mean that it’s a little harder to set up than others. That said, set-up is generally a one-time deal, but it’s nice to be able to refer to a “single source of truth” instead of jumping all over the show.

Unit testing allows you to ensure that your developed modules are meeting the requirements specified by the business document. These tests are written for every module as they are created. After every new module development, the entire suite of test cases is run to ensure that no existing modules are affected by the developed module. If you’re Coding for kids we support schools children and young people! new to the game and need a lot of help getting up to speed, you should choose frameworks with strong communities like Jest. If you require a broad API along with specific features then Mocha is a smart choice, as the extensibility is there. And if your tests are mostly E2E, then you can choose between Cypress, Puppeteer or Playwright.

If you’ve been a programmer even for just a couple of years, you’ll understand how important it is to choose a framework with a strong community and active support. When a tool is also backed up by a giant like Meta, there’s considerable extra comfort and peace of mind. JavaScript moves fast, but JavaScript developers move even faster!

# Features

This framework aims to position itself as the Test Runner of choice for Vite projects, and as a solid alternative even for projects not using Vite. The team has provided a comparison page which shows you the differences between this tool and the most-used test runners like Jest or Cypress. Made by the team behind Vite, Vitest is a native test runner which provides a compatible API that allows developers to use it as a drop-in replacement of Jest in most projects. Straightforward API. It provides a clean and easy-to-understand syntax, and also a rich and straightforward API for writing your unit tests. But Cypress also supports other JS frameworks, including Angular and Node. But the key difference between the two is that Cypress doesn’t need to integrate with your code.

As unit testing requires breaking down the AUT into many small and individual units, it becomes too costly to be executed manually. Manual testing also has an undeniable factor of human error, which is too big a risk. But, automated unit testing can run unit tests much faster with better coverage and no scope of human error. As a result, numerous JavaScript testing frameworks can be used to perform unit testing.

Unit Tests

Cypress framework is a JavaScript-based end-to-end testing framework built on top of Mocha making asynchronous testing simple and convenient. Unit tests in Cypress are executed without even having to run a web server making it the ideal tool for testing a JS/TS library that is meant to be used in the browser. Stateofjs collects data from thousands of front-end developers in its annual surveys.

js unit testing framework

It follows a serial methodology to run tests to deliver more precise reporting while mapping uncaught issues to their respective test cases. Mocha also has methods that execute in a particular order, logging the results in a separate terminal window. It also clears the state of the software being tested to ensure that test cases run in isolation. Ideally, the QA team should share the responsibility of choosing and structuring the framework. Hosted on Github, Mocha is recognized for its flexibility, and as a result, it has proven to be one of the most dependent libraries among JavaScript developers. ChaiJS works with Node, browser, rail and got great support community and documentation.

Can JavaScript be unit tested?

They provide us with a way to test how processes affect selected component structures and data structure without actually rendering them into a browser or a browser-like environment. This guide is intended to catch you up with the most important reasoning, terms, tools, and approaches to JavaScript testing for the year 2022. In addition, AVA boasts a simple syntax, enforces the writing of atomic tests, and provides a magic assert feature with assertion differences that are easy to understand. As you can see in the State of JS 2020 survey results, Mocha was once the most preferred JavaScript testing framework for a significant period of time.

js unit testing framework

While it is not limited in terms of functionality, it forces writing tests that follow very simple structure and assertions. For instance, Ava doesn’t have explicit test suites, so you can’t group your tests at a more nested level than the file level. Jest has been the most popular testing framework for JavaScript for a few years now. It works with Node.js, TypeScript, React, Angular, Vue, Svelte and Babel. It was created and is maintained by Facebook, and is strongly inspired by Jasmine. Vue Testing Library is a set of tools focused on testing components without relying on implementation details.

Why automate Unit testing?

It’s an important property to be able to trust the output of your tests. You don’t want interference to happen between the different test cases. On top of that, tests finish much faster due to their concurrent execution. Cypress is popular among testers and developers because it requires no setup.

Which Cannot be tested using JMeter?

For example, JMeter does not support JavaScript, and therefore, cannot support AJAX requests, so in this case, JMeter can only simulate HTTP traffic. JMeter allows emulating SPA web requests to the server without testing the application itself.

TestCafe is a Node.js based end-to-end framework that aims to provide easy setup so that developers can focus on creating tests that are easy to write and reliable. One of the primary benefits that end-to-end testing is known for is its ability to test your application across multiple browsers. As a result, it is important to be mindful of this trade-off when choosing the amount of cross-browser testing your application needs. This section aims to provide guidance to navigating the testing ecosystem and choosing the right tools for your Vue application or component library. Nightwatch has its own implementation of the selenium WebDriver. And provides its own testing framework with a test server, assertions, and tools.


Sometimes a framework might be used to expose the browser’s API in a different way. When the test runs, and the new snapshot differs from the last one, the developer is prompted to confirm that the change is intended. The following example, from the official Jest documentation, shows a snapshot test of a certain Link component. Sinon can, for example, fake a server to ensure offline, fast and expected responses when testing a certain flow. Used to fake certain modules or behaviors to test different parts of a processes.

Extensive and easy-to-use mocking to help replace slow dependencies, including timer mocks, Ecma 6 script class mocks, and manual module mocks. Jasmine has supported async spec functions and waiting on returned promises for two years now. Fourth, refactoring code is made easier, because changes can be verified using tests to ensure that the unit being tested still behaves in the desired manner. If you are looking to make a career in the field of JavaScript testing, then you can take LambdaTest JavaScript 101 Certification to empower and boost your JavaScript test automation skills.

  • In some companies it takes hours to finish running all the E2E tests.
  • Puppeteer is maintained by Google and has a big community that uses and develops tools and wrappers around it.
  • You need Jest to collect all the test files with the .test.js extension, run each one, and show pass/failed results.
  • Unit testing is a software testing method in which individual pieces of code are tested in isolation.

Jasmine is another of the best JavaScript unit testing frameworks. It is open-source and used as a behavior-driven development tool. In behavior-driven development, test cases are written even before writing the actual code that is to be tested. Jasmine is not limited to JavaScript; you can use it for other programming languages like Python, Ruby, and much more. Unlike other JS testing frameworks, Storybook is more of a UI testing tool.

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