JavaScript Testing Frameworks: The Best to Test JS Code

Imagine building the sleekest app ever, only to watch it crumble like a cookie at the first tap. Ouch, right? Nobody wants that. This nightmare is why we can’t avoid talking about JavaScript testing frameworks. It’s the safety net for your code.

In this digital era, where JavaScript reigns, ensuring your application is robust and bug-free isn’t just a nice-to-have; it’s a must. Consider this your virtual toolkit, where I’ll unpack the essentials of Mocha to Jest, and from Chai to Sinon, guiding you through the labyrinth of testing options.

By the end of this deep-dive, you’ll be ready to integrate automated testing into your development process, armed with knowledge on test runners and automation tools that’ll help your code stand the test of time—and users.

We’ll cover:

The A-Z of test automation
Harnessing continuous integration for peace of mind
Mastering Mocha, Jasmine, and Jest
The hidden gems within asynchronous testing

Roll up your sleeves; it’s time to make your code bulletproof.

JavaScript testing frameworks to check out

ProdPerfect

ProdPerfect is a cloud-based test automation solutions provider that uses live traffic to automatically build, run, and maintain QA testing for web applications.

It addresses critical test coverage gaps, eliminates long test suite runtimes and costly bugs in production, and removes the QA burden that consumes massive engineering resources.

ProdPerfect is designed for businesses of all sizes and is a fully-managed, end-to-end (E2E) regression testing solution that auto-detects user behavior patterns and deploys test code that repeats these patterns in a test environment through CI/CD.

Jasmine

Jasmine is a behavior-driven development framework for testing JavaScript code. It does not depend on any other JavaScript frameworks. It does not require a DOM.

And it has a clean, obvious syntax so that you can easily write tests.

Mocha

Mocha is a feature-rich JavaScript test framework running on Node.js and in the browser, making asynchronous testing simple and fun.

Mocha tests run serially, allowing for flexible and accurate reporting, while mapping uncaught exceptions to the correct test cases.

PhantomJS

PhantomJS is a headless WebKit scriptable with a JavaScript API. It has fast and native support for various web standards: DOM handling, CSS selector, JSON, Canvas, and SVG.

Jest

Jest is used by Facebook to test all JavaScript code including React applications.

One of Jest’s philosophies is to provide an integrated “zero-configuration” experience. We observed that when engineers are provided with ready-to-use tools, they end up writing more tests, which in turn results in more stable and healthy code bases.

Karma

The main goal for Karma is to bring a productive testing environment to developers.

The environment being one where they don’t have to set up loads of configurations, but rather a place where developers can just write the code and get instant feedback from their tests.

Because getting quick feedback is what makes you productive and creative.

FuncUnit

FuncUnit enhances assertion libraries like QUnit and Jasmine, enabling them to simulate user actions, easily test asynchronous behavior, and support black box testing. Use its terse jQuery-like syntax to superpower your functional or unit tests.

Intern

Intern is a complete test system for JavaScript designed to help you write and run consistent, high-quality test cases for your JavaScript libraries and applications. It can be used to test any JavaScript code.

Intern is minimally prescriptive and enforces only a basic set of best practices designed to ensure your tests stay maintainable over time.

Its extensible architecture allows you to write custom test interfaces, executors, and reporters to influence how your tests run & easily integrate with your existing coding environment.

Intern also comes with Grunt tasks so it can be quickly added to existing Grunt-based workflows, and is designed to work out-of-the-box with popular continuous integration services like Jenkins and Travis CI.

Watir

An open source Ruby library for automating tests. Watir interacts with a browser the same way people do: clicking links, filling out forms and validating text.

Istanbul

Istanbul instruments your ES5 and ES2015+ JavaScript code with line counters, so that you can track how well your unit-tests exercise your codebase.

Enzyme

Enzyme is a JavaScript Testing utility for React that makes it easier to assert, manipulate, and traverse your React Components’ output.

Enzyme’s API is meant to be intuitive and flexible by mimicking jQuery’s API for DOM manipulation and traversal.

Enzyme is unopinionated regarding which test runner or assertion library you use, and should be compatible with all major test runners and assertion libraries out there. The documentation and examples for enzyme use mocha and chai, but you should be able to extrapolate to your framework of choice.

testdouble.js

Are you writing JavaScript tests and in the market for a mocking library to fake out real things for you? testdouble.js is an opinionated, carefully-designed test double library maintained by, oddly enough, a software agency that’s also named Test Double.

If you practice test-driven development, testdouble.js was designed to promote terse, clear, and easy-to-understand tests. There’s an awful lot to cover, so please take some time and enjoy our documentation, which itself is designed to show you how to make the most out of test doubles in your tests.

Ava

Even though JavaScript is single-threaded, IO in Node.js can happen in parallel due to its async nature.

AVA takes advantage of this and runs your tests concurrently, which is especially beneficial for IO heavy tests.

In addition, test files are run in parallel as separate processes, giving you even better performance and an isolated environment for each test file. Switching from Mocha to AVA in Pageres brought the test time down from 31 to 11 seconds.

Having tests run concurrently forces you to write atomic tests, meaning tests don’t depend on global state or the state of other tests, which is a great thing!

Nightwatch.js

Nightwatch.js is an easy to use Node.js based End-to-End (E2E) testing solution for browser based apps and websites. It uses the powerful W3C WebDriver API to perform commands and assertions on DOM elements.

Protractor

Protractor is an end-to-end test framework for Angular and AngularJS applications. Protractor runs tests against your application running in a real browser, interacting with it as a user would.

Cucumber

Cucumber supports over a dozen different software platforms. Every Cucumber implementation provides the same overall functionality, but they also have their own installation procedure and platform-specific functionality. Cucumber is one of the Javascript testing frameworks that people often recommend.

Wallaby.js

Wallaby.js runs your JavaScript tests immediately as you type and displays execution results in your code editor. It also provides beautiful test and code coverage reports updated in realtime.

TestCafe

TestCafe is a pure node.js end-to-end solution for testing web apps. This Javascript testing framework takes care of all the stages: starting browsers, running tests, gathering test results and generating reports. TestCafe doesn’t need browser plugins – it works in all popular modern browsers out-of-the-box.

QUnit

QUnit is a powerful, easy-to-use JavaScript unit test suite. It’s used by the jQuery, jQuery UI and jQuery Mobile projects and is capable of testing any generic JavaScript code, including itself

Cypress

Cypress is a test engine that runs unit and integration tests in your browser.

Drive your application with automated tests instead of manually verifying that your app works. Don’t spend days setting up a test environment. Just download our desktop app, add your project and start testing! Seriously.

You don’t need to change your code and Cypress doesn’t need to modify your code. Test in any major language or framework. Does your app run in a browser? Yes? You can test it in Cypress.

Chai

Chai is a BDD / TDD assertion library for node and the browser that can be delightfully paired with any Javascript testing framework.

CasperJS

CasperJS is an open source navigation scripting & testing utility written in Javascript and based on PhantomJS — the scriptable headless WebKit engine. It eases the process of defining a full navigation scenario and provides useful high-level functions, methods & syntactic sugar for doing common tasks

Sinon.JS

Sinon is another one of these Javascript testing frameworks. Standalone and test framework agnostic JavaScript test spies, stubs and mocks (pronounced “sigh-non”, named after Sinon, the warrior).

Zombie.js

If you’re going to write an insanely fast, headless browser, how can you not call it Zombie? Zombie it is.

Zombie.js is a lightweight framework for testing client-side JavaScript code in a simulated environment. No browser required.

Should

should is an expressive, readable, framework-agnostic assertion library. The main goals of this library are to be expressive and to be helpful. It keeps your test code clean, and your error messages helpful.

By default (when you require(‘should’)) should extends the Object.prototype with a single non-enumerable getter that allows you to express how that object should behave. It also returns itself when required with require.

It is also possible to use should.js without getter (it will not even try to extend Object.prototype), just require(‘should/as-function’). Or if you already use version that auto add getter, you can call .noConflict function.

Selenium

Selenium is the last of the Javascript testing frameworks included in this article. It automates browsers. That’s it! What you do with that power is entirely up to you. Primarily, it is for automating web applications for testing purposes, but is certainly not limited to just that. Boring web-based administration tasks can (and should!) be automated as well.

FAQ on Javascript testing frameworks

What Exactly Are JavaScript Testing Frameworks?

Trust me, it’s like having a spell-checker for your code. These frameworks, think Mocha or Jest, are a developer’s best pals for squashing bugs and keeping things running smooth. They automate the grind of checking if every line plays nice together and behaves as expected.

Why Should I Use a Testing Framework in JavaScript?

Imagine shipping a product then facing backlash coz something broke. Testing frameworks are your quality assurance squad. They ensure your app’s logic is airtight so you can avoid those pesky error messages that make users go ‘ugh’ and keep’em coming back for more.

How Do JavaScript Testing Frameworks Integrate with CI/CD?

Ah, the beauty of modern devops. With testing frameworks in the mix, your code is constantly being tested every time it’s pushed to the repo. Tools like Travis CI and Jenkins give your code a workout and make sure it’s fit for deployment, automated and hassle-free.

What’s the Difference Between Unit Testing and End-to-End Testing?

Let’s break it down: Unit testing is like checking each individual cookie in the batch. End-to-end (E2E) testing? That’s more like tasting the whole cookie jar to ensure the flavor’s consistent. Simply put, unit tests cover the basics while E2E tests the user experience from start to finish.

Can I Test Asynchronous Code With JavaScript Testing Frameworks?

Absolutely! Asynchronous code can be a headache but frameworks like Jest come to the rescue. They’re equipped to wait around for those promises to resolve or those callbacks to… well, callback. Say goodbye to timing issues throwing your tests off track.

What’s the Best JavaScript Testing Framework for Beginners?

Jest has got to be your go-to. User-friendly? Check. Great docs? Check. Plus, it’s got a strong community. Gets you up and running with less fiddling around, so you’re less ‘What the heck?!’ and more ‘Heck, yeah!’

Should I Write Tests Before or After Coding?

Ha! The old TDD debate. Test-Driven Development (TDD) says write tests first to guide your coding. BDD (Behavior-Driven Development) takes it up a notch focusing on the user’s experience. But hey, even if you code first, just make sure you test. Test, test, test.

How Often Should My JavaScript Code Be Tested?

Continuous integration, my friend. Think of it as a safety net that never sleeps. Each time you push a change, your testing framework and CI tools join forces to keep your codebase solid. Regular testing? It’s like brushing your teeth – do it often for best results.

What Are Mocking Libraries and Why Use Them?

Imagine you’re a puppet master, and your code is the puppet. Mocking libraries let you control how your code behaves in tests. Why? Because sometimes real-world conditions are a pain to replicate. Libraries like Sinon can fake server responses, timers, the works – super handy.

How Do I Ensure My Tests Cover All Possible Cases?

Cover your bases with code coverage tools like Istanbul. They give you the lowdown on what’s tested and what’s missing the mark. It’s like having a report card showing which parts of your code are playing hooky from testing. No cheating allowed, every line’s gotta pass!

Conclusion

Alright, so we’ve been through the twists and turns of JavaScript testing frameworks. From the sturdy scaffolding provided by Mocha, to the cozy comforts of Jasmine, and the powerhouse that is Jest, we’ve seen how these frameworks give our code the armor it needs to survive the wilds of the web.

Key takeaway? Automation is your secret sidekick.
Trust in test runners.
Embrace unit and E2E tests – they’ve got your back.

Finding the right fit might take a bit, but it’s like digging through a treasure chest – there’s gold in there. Whether you’re a solo adventurer or part of a coder crew, tests are your trusty compass.

Let’s wrap it up. Keep those tests running, lean on your CI tools, and remember – each test is a step towards cleaner, meaner, and more resilient code. The journey doesn’t end here; it’s just getting started. Keep exploring, keep testing.

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Bogdan Sandu

Bogdan Sandu, a seasoned designer with 15 years of diverse experience, has been designing websites since 2008.

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