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What is Qunit ?

  • Last Updated : 12 Aug, 2021

Introduction: Qunit is a JavaScript Testing Framework for checking JavaScript code. It’s primarily utilized in JQuery projects. QUnit can be used by developers working on JavaScript applications to test their JS codebase.

It primarily adheres to the CommonJS unit testing specifications, which essentially contain the goals of using JavaScript outside of the web browser, i.e. making JS modular and allowing it to be used in a variety of multiplatform applications.

Testing: Testing is the process of reviewing an application’s functionality to determine whether it fits the requirements and to ensure that unit testing is used at the developer level.

Also, the process of testing any individual class or method is known as Unit Testing as it is required to develop scalable products. Moreover, this unit testing could be performed in multiple ways which can be either the execution of the test cases manually without any tool support is known as Manual Testing, or else, taking the tool support and execution of the test cases using automation tool is known as Automation Testing.

Now, as we are familiar with what basically is QUnit and what is its purpose, let’s get on to learn how to use it and how to set it up.

How to install/ use QUnit?

We can use it either by NodeJS (installing it locally on the machine) or by CDN (directly in the browser)

The official release packages for QUnit are as follows:

  • npm

    npm install --save-dev qunit
  • yarn

    yarn add --dev qunit
  • bower

    bower install --save-dev qunit

Example: Now to demonstrate the testing we will use CDN for the ease of accessibility, We will perform a basic testing format to get the crux behind QUnit testing. Here, we used a simple function messageHandler which will print a string and a number and a Testcase will assert its output to check its correctness.

Note: As we are using CDN, just make a folder, and open it in your IDE to make an empty file 


<!DOCTYPE html>
    <meta charset="utf-8" />
    <title>QUnit | GeeksForGeeks</title>
    <!-- The CDN Links for QUnit (IMPORTANT: Only use 
        these CDN links if you are testing without 
        using node.js/dependencies) -->
    <link rel="stylesheet" href=
    <script src=
    <!-- QUnit Frontend Toolbar (Fixture) -->
    <div id="qunit"></div>
    <div id="qunit-fixture"></div>
    <!-- Testing Script -->
        // Function which we will test (Unit Testing)
        // Returns a message + a number
        function messageHandler(message, x) {
            const result = (message + " " + x).toString();
            return result;
        // Testcase to assert result
        QUnit.test("Testing Message Function", function(assert) {
            var value = messageHandler("GeeksForGeeks", 10);
                "GeeksForGeeks 10",
                "Result should be GeeksForGeeks 10."


Explanation: As the input matches the required output the TestCase is successfully passed. The test runner calls QUnit.test() when the page gets loaded and adds the test to a queue. The execution of test cases is deferred and controlled by the test runner.

Let’s check what will happen if the test case gets failed:

Explanation: This time, we passed the integer 1000 instead of 10 which resulted in the test case failure as shown in the error output which makes us easier to debug the code.

Now let’s see the functioning of the above testing procedure:

  • Setting Up the index.html:  In order to view the testing output, we have to use two of the pre-defined QUnit ids which will help render the output in the target divs on the webpage.

    <div id = "qunit"></div>
    <div id = "qunit-fixture"></div>
  • The Testing Function: Now, we have defined our function of which the output has to be tested, here messageHandler(message, x). It takes a string text and an integer number and returns it concatenated. These functions are what we perform unit testing on.

  • Testcase Assertion:

    QUnit.test("Test", function(assert) {

    This is the predefined module of QUnit that we use to assert whether the testing function’s output is equal to the asserted value. This same result will be rendered into the output div on the webpage. Moreover, this is the place where any of the vast testing modules and functions can be implemented as per the requirements of testing the code.

  • Main Features of QUnit:

    • It’s an open-source framework for testing JS code.
    • It includes Test Fixtures for running tests, as well as a clear list of problems.
    • QUnit also helps by providing assertions to test expected results.
    • Ease of code debugging.
  • Some important APIs provided by QUnit:



    Async Control

    Methods to handle asynchronous operations that require some time to execute

    CallbacksProvides methods to read results
    ConfigProvides custom assertions, and utility helpers
    AssertionProvides Assert methods.
    TestingMethods to test the code.

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