Jest vs Mocha vs Jasmine: Top 3 JavaScript Testing Frameworks

JavaScript is the most popular programming language. In recent days, many UI frameworks have been built with JavaScript-based NodeJS platforms such as React, Angular, Vue, etc. TypeScript also internally utilizes JavaScript, as TypeScript is a typed superset of JavaScript. There was a time NUnit, XUnit, and JUnit testing frameworks were ruling the market. As JavaScript gained popularity, many testing frameworks emerged to support JavaScript/TypeScript-based applications. Let’s analyze the top three JavaScript Testing Frameworks: Jest vs Mocha vs Jasmine.

Many browser-based automation testing frameworks, such as Cypress, Puppeteer, and Selenium JavaScript bindings, rely on these frameworks internally. Before that, let’s discuss why unit testing is essential for JavaScript applications.

What is JavaScript Testing Framework?

The JavaScript testing framework is a testing library, which supports testing front-end applications by providing assertions, code coverage, mocking, etc., and ensures the correctness of the developed feature.

Types of Testing

Software application testing can be broadly categorized into two levels:

• End-to-End Testing: This is browser-based testing, in a layman’s term simulation of user-based scenarios. This requires launching the browser, simulating user actions, and validating them. Tools such as Cypress, WebdriverIO, and Puppeteer are examples. Generally, end-to-end testing tools provide the simulation feature to verify the outcome of the use cases; it depends on test libraries such as Mocha, Jest or Jasmine, etc.
• Unit Testing: This generally doesn’t require browsers to run the test; individual components will be tested against the requirements. The test libraries, such as Jest, Mocha, and Jasmine, are configured to run the unit tests. Whenever there are new features or bug fixes, the developer should ensure that unit testing is in place.

Jest, Mocha, and Jasmine have gained popularity as they are necessary for unit testing, integration testing, and end-to-end testing. Its scope is not limited to JavaScript; it supports TypeScript as well.

Why do we need Unit Testing for JavaScript applications?

The modern software development architecture recommends TDD (Test Driven Development) or BDD (Behavior Driven Development) as the mandatory practice while application development, as it has many advantages and helps to deliver a quality product. Below are some common benefits of unit testing:

• Early detection of bugs: Unit testing is one of the easiest and most cost-effective ways to prevent bugs. Unit testing checks the logic at the component level, ensuring that the component is working as expected.
• Early detection of regressions: When the developer changes the code to fix the bug or add a new feature, the unit test reports the failure, which helps in the early detection of the bugs.
• Saves cost: Any bug caught later in development is costlier, as it has to go through multiple processes, and a lot of effort is involved. When there is an effort, there is a cost. Since unit testing helps in the early detection of bugs, it saves many expenses in the long run.
• Defect prevention: Well-written unit tests can prevent the defect, as the test fails instantly, preventing the unintended modification of code.
• Quality gate: Unit testing serves as a quality gate, as the percentage of code coverage can be measured and set the quality gate as per the requirement. The code merge fails instantly if the coverage is below the required limit.

Let’s compare the three testing JavaScript frameworks: Jest vs Jasmine vs Mocha.

Jest vs Mocha vs Jasmine: Why compare them?

These three frameworks have existed for a long time and are quite popular in the market. Whenever the question arises about the best among these three, the answer is always debatable. However, by analyzing their features, limitations, and trends in the market, we should be able to conclude which is the best framework. All three frameworks were released a decade back.

Jest, Mocha, and Jasmine’s initial release dates

• Jasmine’s Initial release was on September 14, 2010
• Jest was created in 2011, and it was made open-source in 2014
• Mocha’s initial release was on 22 November 2011

These three frameworks perform well even after a decade, so it’s worth exploring and comparing them. This article compares them in an unbiased way.

The above image shows the satisfaction ranking of testing libraries. Jest is in the Top 3, Mocha is in the Top 8, and Jasmine is in the Top 10. This ranking is a comparison of all JavaScript testing frameworks, both unit and end-to-end testing frameworks. As mentioned earlier, some end-to-end testing framework uses one of these libraries, for example, Cypress internally uses Mocha/Chai libraries. The above ranking can be used as a reference but not for a conclusion unless you evaluate the features against your organization’s requirements.

Jest JavaScript Testing Framework

Jest is an open-source JavaScript testing framework managed by Facebook, Inc. It supports different types of front-end projects such as Babel, TypeScript, Node, React, Angular, Vue, etc. Jest was built for the Facebook chat feature and was created in JavaScript. The framework is enhanced to support many core features and open source. The Meta (formerly Facebook) open-source project was maintaining the Jest framework, but Meta has decided to hand over Jest to the OpenJS foundation.

Jest Data on NPM and GitHub

• Weekly Downloads: 17,153,924
• Used by: 6.4M
• Contributors: 1,387
• Forks: 6K
• Star: 40.1K
• License: MIT

Advantages of Jest JavaScript Testing Framework

• Zero config setup. Jest is easy to set up. Install the Jest package using npm or Yarn and start writing the test.
• Jest test execution is comparatively faster; parallel testing makes it even faster.
• Jest framework provides an easy mocking feature with rich mock functions; you just need to import and start spying on functions.
• Rich assertions make Jest provide the accurate results.
• Detailed documentation lists every feature with examples, which helps anyone to understand and resolve the problem.
• Snapshot testing or Visual testing is another key feature of the Jest framework. The Snapshot testing helps validate UI bugs, for example, layout, typography, alignment, etc.
• Easy to debug and resolve the failures.
• Some of the critical features of Jest include clear output, powerful developer tools, frequent releases, lightweight, etc.

Learn More: Uncaught Type Error in Javascript 

Limitations of Jest Framework

• People who worked with other testing libraries may find it hard to learn Jest.
• Jest is not supported by all IDE. If you are using the unsupported IDE, you might not get powerful features like IntelliSense, auto import, etc.
• Compared to other similar libraries, Jest lacks the library and tooling support.
• The auto mocking feature makes Jest slower.

Mocha JavaScript Testing Framework

Mocha is an open-source JavaScript testing framework built by NodeJS. It is part of the OpenJS foundation. Mocha is consistently the first choice of developers for a long time. This framework always concentrates on core features and extensibility. To make the most out of Mocha and ensure effective testing of JavaScript applications, businesses can hire Node js developers with expertise in Mocha.

Mocha Trends on NPM and GitHub

• Weekly Downloads: 6,659,493
• Used by: 1.7M
• Contributors: 480
• Forks: 3K
• Star: 21.6K
• License: MIT

Advantages of Mocha Testing Framework

Mocha is a simple and flexible framework; it doesn’t come with assertion libraries you can use any assertions libraries. The Chai, Sinon, Express.js, and Should.js libraries are the most popular assertion libraries with Mocha. It can be used for both front-end and back-end testing. As it is flexible, Mocha can be configured to work on any project such as React, Angular, etc.

• Mocha supports Test Driven Development (TDD) and Behavior Driving Development (BDD).
• Mocha test runs serially, so results are always accurate.
• Mocha tests can be set up to run test cases directly on the web browser.
• It provides various ways to generate the test report; you can even choose to create custom reports.
• It can be configured for synchronous or asynchronous testing.
• Mocha provides a good number of plugins that helps to extend your framework.
• Mocha highlights the slow running tests after the test run.
• Mocha supports the retry failed tests feature, which helps to configure re-running the failed tests if tests are flaky.

Limitations of Mocha Framework

• The developer needs to spend time configuring and setting up the Mocha framework.
• Snapshot testing is not supported out of the box; you need to depend on external libraries.
• Though it has good documentation, the search feature is not user-friendly.
• As you have to integrate different frameworks for assertions, the test scripts can sometimes be confusing.
• Mocha is falling behind in releasing new features and supporting developer tools nowadays.

Jasmine JavaScript Testing Framework

Initially released in September 2010, Jasmine is an open-source JavaScript framework that runs with NodeJS. It supports BDD development. Everything needed for testing is shipped as a single package in Jasmine. It has inbuilt assertions, so there is no need to configure external assertion libraries. Jasmine is an independent testing library. Jest and Mocha share the syntaxes and similarities with Jasmine. Jasmine existed even before Mocha and Jest, making it one of the oldest JavaScript testing frameworks.

Jasmine Facts on NPM and GitHub

• Weekly Downloads: 4,278,068
• Used by: 2.4M
• Contributors: 218
• Forks: 2.3K
• Star: 15.4K
• License: MIT

Advantages of Jasmine JavaScript Framework

Jasmine ships all the features out-of-the-box that are required for unit tests; you do not have to download any external libraries.

• Jasmine can be used with any popular development framework.
• Jasmine supports asynchronous testing.
• Jasmine’s syntaxes are clear, and the tests are more readable.
• Good community support is a big plus for Jasmine, as it has existed as a popular framework for a long time.
• Jasmine provides good tool and extension support, which helps to customize and extend the framework.
• Jasmine provides a variety of assertions; it is more readable and easier to use.

Limitations of Jasmine

• Jasmine provides everything out of the box, but the user has to spend time configuring them.
• It has good documentation, but not documented in a user-friendly way.
• Asynchronous testing is complex with Jasmine.

Jest vs Mocha vs Jasmine: Which one to choose?

It’s tough to conclude which is better, as every framework has its pros and cons. The testing framework cannot be chosen based on trends, popularity, or usage. Several criteria need to be evaluated while choosing the testing framework, for example, the front-end development library, type of application, skillsets, etc. After assessing the organization and project requirements, the testing framework needs to be integrated.

If you consider the popularity, Jest is mostly popular with ReactJS and NextJS-based applications, and Jasmine is popular with Angular-based applications. The complex projects choose the Mocha testing framework as it provides a lot of flexibility. Having said that, no framework can be considered the best. However, if the framework fulfills your project and organization requirements, that is the best for you.

We know that unit testing is part of the application testing and resides at the lower level before integrating the components. The actual behavior can be tested only after integrating all the components by performing end-to-end testing. Like Unit testing tools, many tools provide end-to-end testing functionality. The common problem with testing tools is that though they use the same programming languages, their usage and configuration are different. So one needs to invest time and effort in learning them.

Interestingly, Testsigma provides scriptless testing, so you don’t have to install any tool to perform end-to-end testing. Once you sign up, you can start writing your tests in plain English. Writing the tests in simple English feature encourages everyone to contribute to testing and eliminates setup time and learning efforts.