Testing is a critical aspect of software development. It ensures that your code works as expected and helps catch bugs early. For jQuery, a popular JavaScript library, QUnit is a great choice for testing. QUnit is a powerful, easy-to-use JavaScript unit testing framework. It was originally developed by the jQuery team and is used to test the jQuery library itself. In this chapter, we will explore how to test jQuery code using QUnit from basics to advanced concepts.
QUnit is a JavaScript unit testing framework designed to help you test your code in a structured and reliable way. It provides a simple API for writing tests and assertions, making it easier to verify the correctness of your code.
Setting up QUnit is straightforward. You can include QUnit in your project by either downloading it or using a CDN.
You can also include QUnit from a CDN:
QUnit provides a simple API for writing tests. The two main functions you’ll use are QUnit.module
and QUnit.test
.
QUnit.module
is used to group related tests together. This makes it easier to organize your tests and understand the context of each test.
QUnit.module('Module Name', {
before: function() {
// This runs before each test in the module.
},
after: function() {
// This runs after each test in the module.
}
});
QUnit.test
is used to define individual tests.
QUnit.test('Test Name', function(assert) {
assert.ok(true, 'This test will pass.');
assert.equal(1, 1, '1 equals 1');
});
QUnit provides various assertion methods to validate the results of your tests:
assert.ok(value, message)
: Passes if value
is truthy.assert.equal(actual, expected, message)
: Passes if actual
equals expected
.assert.deepEqual(actual, expected, message)
: Passes if actual
and expected
are deeply equal.assert.throws(function, expected, message)
: Passes if the function throws an exception.Let’s write a simple test to understand the basics.
QUnit.module('Example Module');
QUnit.test('Simple Test', function(assert) {
assert.ok(true, 'This test will always pass.');
assert.equal(2 + 2, 4, '2 + 2 equals 4');
});
true
is truthy.2 + 2
equals 4
.Testing jQuery selectors ensures that your code correctly selects the desired elements.
Hello World
QUnit.module('jQuery Selectors');
QUnit.test('Selects element by class', function(assert) {
var element = $('.test-element');
assert.ok(element.length > 0, 'Element with class "test-element" exists.');
assert.equal(element.text(), 'Hello World', 'Element text is "Hello World".');
});
test-element
.test-element
exists and has the correct text.Testing jQuery events ensures that your event handlers work as expected.
QUnit.module('jQuery Events');
QUnit.test('Button click event', function(assert) {
var done = assert.async();
$('#test-button').on('click', function() {
assert.ok(true, 'Button was clicked.');
done();
});
$('#test-button').trigger('click');
});
test-button
.Testing AJAX calls ensures that your asynchronous code works as expected.
QUnit.module('jQuery AJAX');
QUnit.test('AJAX request', function(assert) {
var done = assert.async();
$.ajax({
url: 'https://jsonplaceholder.typicode.com/posts/1',
method: 'GET',
success: function(data) {
assert.ok(data, 'AJAX call succeeded.');
assert.equal(data.id, 1, 'Returned data has correct ID.');
done();
},
error: function() {
assert.ok(false, 'AJAX call failed.');
done();
}
});
});
Mocking and stubbing are techniques used to simulate the behavior of real objects in testing. This is particularly useful for testing functions that rely on external systems or data.
To mock jQuery AJAX calls, you can use libraries like sinon.js
.
QUnit.module('Mocking and Stubbing', {
beforeEach: function() {
this.server = sinon.createFakeServer();
},
afterEach: function() {
this.server.restore();
}
});
QUnit.test('Mocking an AJAX request', function(assert) {
var done = assert.async();
this.server.respondWith('GET', '/api/data', [
200,
{ 'Content-Type': 'application/json' },
JSON.stringify({ id: 1, name: 'Test' })
]);
$.ajax({
url: '/api/data',
method: 'GET',
success: function(data) {
assert.equal(data.id, 1, 'ID is correct.');
assert.equal(data.name, 'Test', 'Name is correct.');
done();
}
});
this.server.respond();
});
Running QUnit tests in the browser is simple. Just open your HTML file with the QUnit setup, and you will see the QUnit test runner interface.
Continuous Integration (CI) and Continuous Deployment (CD) are practices that help automate the testing and deployment process. Integrating QUnit with CI/CD ensures that your tests run automatically whenever code is pushed to the repository.
GitHub Actions is a CI/CD service provided by GitHub. You can set up a workflow to run QUnit tests.
name: CI
on: [push, pull_request]
jobs:
test:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v2
- name: Set up Node.js
uses: actions/setup-node@v2
with:
node-version: '14'
- run: npm install -g qunit
- run: qunit my-tests.js
In this chapter, we covered the basics and advanced concepts of testing jQuery code with QUnit. We started with setting up QUnit, writing simple tests, and gradually moved to more complex scenarios like testing jQuery selectors, events, and AJAX calls. We also explored advanced topics like mocking, running tests in the browser, integrating with CI/CD, and using custom assertions. Happy coding !❤️