What Is Mocha? A Powerful JavaScript Testing Framework

Mocha is such a popular name that there is hardly anyone who builds JavaScript applications but hasn’t heard about Mocha or doesn’t use it. It is an amazing testing framework that is mostly used for testing JavaScript-based applications.

In our previous articles about Jest, you must have read about how it easily integrates with Mocha. Now, you must know why integrating with Mocha is so beneficial and why it holds such an important place among the most famous JavaScript testing frameworks.

What Is Mocha.js?

Mocha is a highly powerful testing framework that runs on Node.js and is capable of easily testing asynchronous JavaScript concepts in the browser. The best part about using this framework is that it allows you to serially perform flexible and accurate tests so that your speed or efficiency does not get compromised.

Besides the accuracy, speed, and efficiency in testing, Mocha provides you with amazing features like -

  • It enables you to write structured code that minutely tests your application.
  • Using it allows you to classify the test codes into test suites and test cases.
  • You can use it to map errors to corresponding test cases so that you can produce a test report after the run.
  • It supports any number of test interfaces including Exports, TSS, Require, and QUnit.

As Mocha’s default interface is a Behavior-Driven Development (BDD), it makes it possible to develop predictable software that is resilient to changes and less prone to errors.

How Did Mocha.js Grow?

JavaScript is by far the most widely used programming language for building web-based and mobile applications. So, the testers have always been on the lookout for powerful testing frameworks that enable them to create complete end-to-end automated test suites and not just unit tests.

And, in such a high demand for an efficient testing framework for JavaScript-based applications, Mocha made its name in the market and grew its popularity mainly since 2016.

Why Should You Use It? Or What Are Its Advantages?

Mocha has become popular due to the highly useful advantages that it provides its users with. So, let’s take a look at them to understand them better.

Multiple Installation Options

Being capable of installing any tool in multiple ways gives its users great flexibility. That’s why Mocha is preferred as it allows you to install it in multiple ways such as globally, as a development dependency for your project, or it provides you with the setup to run test cases directly on the web browser.

Great Cross-browser Support

You already have read about the importance of cross-browser testing in our articles, and here the point of discussion is that Mocha is such a testing framework that enables you to easily create effective test cases that run seamlessly on all major web browsers. On top of that, you can also extend it with plugins, and with each revision of Mocha, you get upgraded JavaScript and CSS built for different web browsers.

Supports JavaScript Assertion Libraries

Mocha can turn out to be a highly cost-effective testing solution as it reduces testing costs and speeds up the testing process by providing compatibility for various JavaScript assertion libraries such as Should.js, Express.js, and Chai.

Due to such amazing support for multiple libraries, you become able to easily write lengthy and complex test cases to fulfill the objective that the tests work perfectly without rewriting them.

Multiple Ways To Get Test Reports

You may already know how important it is to get detailed reports of the tests executed by you. That’s why another great benefit of using Mocha is that it provides you with a wide variety of ways to report such as the list reporter, the JSON reporter, and the progress reporter. Hence, it becomes a great advantage that you get to choose the reporting option that is the best suited for your requirements.

Supports Both Synchronous and Asynchronous Testing

Mocha is highly preferred for its ability to strengthen the asynchronous tests with features that invoke the callback once the test is completed. Besides that, it also enables synchronous testing by omitting the callback.

Supports Both BDD and TDD Environments

Mocha makes it easy to write high-quality tests and improves test coverage by supporting both behavior-driven development (BDD) and test-driven development (TDD).

Limitations of Using Mocha.js For Testing

Similar to every other innovation of Mocha.js also has a few limitations that are jotted down below.

  • While using Mocha, if you cannot afford flexibility, you must explicitly choose an assertion library.
  • If you compare Mocha with other frameworks, it requires more configuration, and that makes it less flexible.
  • Mocha snapshot testing is likely to be tricky. For performing it properly, you need to work with the chai-jest-snapshot library.

An In-depth Comparison Between Mocha.js and Jasmine

As a potential user, you must know about various available options to choose the best one for you. In the case of testing frameworks for JavaScript-based applications, Jasmine is a huge competitor for Mocha.

Jasmine is another popular JavaScript testing framework that was created around 2008 and has gradually gained fame for being a complete testing framework that provides everything that a developer may need. It has been improved with numerous features through continuous upgrades since its creation.

On the other hand, due to being created in 2011, Mocha is considered a younger framework and is described as only covering the basics, allowing developers to extend it with other frameworks but is not a complete framework.

Hence, let’s check out a detailed comparison between these two popular frameworks based on their operational aspects.


The test behavior is an extremely important aspect of its success, assertions are the boolean functions that check the test behavior. An ideal case in the assertion result will be that when the test ran, it behaved as expected.

Now, Jasmine comes with a library of assertions that use an expect-style syntax while Mocha does not have any such built-in assertion library.

However, in such cases, the popular Chai assertion library can be used which has a syntax similar to Jasmine.

Test Doubles/Spies

You must have already read about spies in our previous articles. A test double or a spy is a clone of an actual object, and it comes with the same functions as the original object. But, the functions of the spies are “stubbed out” i.e. they don’t actually do anything. The “stubbed” functions are there so that the test double frameworks become capable of watching the spy in action, tracking the calls to its functions.

However, the point is that while test doubles or spies are a super important aspect of software testing, Mocha does not come with this spy framework feature. On the other hand, Jasmine and SinonJS are two popular names that provide you with that feature.

Hence, it can be said that though Mocha does not come with the spy framework, it has amazing abilities to prioritize BDD test definitions and it is really amazing at that. And, the best part is that other frameworks can easily be combined with Mocha to extend its functionality.

These discussions are just to make you aware of different aspects of Mocha and Jasmine along with some of its top competitors. While Mocha and Jasmine both are amazing in their abilities, you must make your choice based on their capabilities of fulfilling your requirements. Also, though any one of them is a great option for you, we would recommend you combine Mocha and Jasmine with Chai and Sinon for making your tests more consistent and readable.

Browsers Supported By Mocha

Mocha is compatible with most popular browsers such as -

  • Google Chrome (27 & above)
  • Safari (7.1 & above)
  • Firefox (10 & above)
  • Edge (15 & above)
  • Opera (69 & above)
  • Internet Explorer (10 & above)


Mocha is a great choice as a JavaScript testing framework for many reasons, and this article surely tells you a lot about it. Now, you just need to go through the complete article for detailed information and decide whether it is the best-suited one for your software testing needs or not.

Here we have jotted down all you need to know about Mocha. That means you will get to know about what it is, how it grew since its inception, what its advantages are, its limitations that you should plan to overcome, how it works compared to Jasmine, another popular testing framework, which browsers it supports, and so on. So, you must consider minutely going through this article.

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