Introduction to QUnit

QUnit is a powerful, easy-to-use JavaScript testing framework primarily used for unit testing JavaScript code. It provides a simple yet effective API to write tests for your applications, making it one of the most preferred choices among developers.

Setting Up QUnit

To get started, you need to include the QUnit library in your project. You can download it or link to it via a CDN:

  <link rel="stylesheet" href="https://code.jquery.com/qunit/qunit-2.18.0.css">
  <script src="https://code.jquery.com/qunit/qunit-2.18.0.js"></script>

Basic Example

Here is a simple example to get you started with QUnit.

  <div id="qunit"></div>
  <div id="qunit-fixture"></div>
  <script>
    QUnit.test("hello test", function(assert) {
      assert.ok(1 == "1", "Passed!");
    });
  </script>

Dozens of Useful APIs

QUnit offers a variety of APIs to enhance your testing experience:

1. QUnit.module

Use this to group related tests.

  QUnit.module("group A");
  QUnit.test("test A1", function(assert) {
    assert.ok(true, "Passed A1!");
  });
  QUnit.test("test A2", function(assert) {
    assert.ok(true, "Passed A2!");
  });
  QUnit.module("group B");
  QUnit.test("test B1", function(assert) {
    assert.ok(true, "Passed B1!");
  });

2. QUnit.test

The most basic way to define a test.

  QUnit.test("example test", function(assert) {
    assert.equal(2 + 2, 4, "Two plus two equals four.");
  });

3. QUnit.skip

Skip a test that you don’t want to run as part of the current suite.

  QUnit.skip("skipped test", function(assert) {
    assert.ok(false, "This test will not run.");
  });

4. QUnit.todo

Mark a test as expected to fail.

  QUnit.todo("todo test", function(assert) {
    assert.ok(false, "This test is expected to fail.");
  });

5. assert.expect

Specify how many assertions are expected in a test.

  QUnit.test("test with expect", function(assert) {
    assert.expect(2);
    assert.ok(true, "First assertion!");
    assert.ok(true, "Second assertion!");
  });

Simple Application Example

Let’s consider a simple calculator application and write tests for its functionalities.

  // Calculator code
  function Calculator() {
    this.add = function(a, b) { return a + b; };
    this.subtract = function(a, b) { return a - b; };
    this.multiply = function(a, b) { return a * b; };
    this.divide = function(a, b) { return a / b; };
  }

  // QUnit tests for Calculator
  QUnit.module("Calculator Tests");
  
  QUnit.test("Addition Test", function(assert) {
    let calc = new Calculator();
    assert.equal(calc.add(1, 1), 2, "1 + 1 equals 2");
  });
  
  QUnit.test("Subtraction Test", function(assert) {
    let calc = new Calculator();
    assert.equal(calc.subtract(2, 1), 1, "2 - 1 equals 1");
  });
  
  QUnit.test("Multiplication Test", function(assert) {
    let calc = new Calculator();
    assert.equal(calc.multiply(2, 3), 6, "2 * 3 equals 6");
  });
  
  QUnit.test("Division Test", function(assert) {
    let calc = new Calculator();
    assert.equal(calc.divide(4, 2), 2, "4 / 2 equals 2");
  });

With these examples, you can see how QUnit simplifies JavaScript testing and ensures your code works as expected. Happy testing!

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