Jasmine and Karma

🔹 What is Jasmine?

• Jasmine is a behavior-driven development (BDD) testing framework for JavaScript.
• It’s mainly used to test JavaScript code (both frontend and backend).
• It provides functions like describe(), it(), and expect() to write human-readable tests.
• No need for DOM or browser—it can run independently.

🔹 What is Karma?

• Karma is a test runner developed by the AngularJS team.
• It doesn’t test by itself—it just runs your Jasmine (or Mocha, etc.) tests in multiple real browsers.
• It helps automate running tests every time you make changes.
• Works well with CI/CD pipelines.

👉 Think of it this way:

• Jasmine = the testing framework (how to write tests).
• Karma = the test runner (where and how to run those tests).

🔹 Example: Jasmine + Karma Setup

Let’s say we have a simple function:

// math.js
function add(a, b) {
  return a + b;
}

// math.js
function add(a, b) {
  return a + b;
}

Now, a Jasmine test would look like this:

// math.spec.js
describe("Add function", function() {
  it("should return the sum of two numbers", function() {
    expect(add(2, 3)).toBe(5);
  });

  it("should handle negative numbers", function() {
    expect(add(-2, -3)).toBe(-5);
  });
});

// math.spec.js
describe("Add function", function() {
  it("should return the sum of two numbers", function() {
    expect(add(2, 3)).toBe(5);
  });

  it("should handle negative numbers", function() {
    expect(add(-2, -3)).toBe(-5);
  });
});

🔹 Running with Karma

• Install dependencies: npm install --save-dev karma jasmine-core karma-jasmine karma-chrome-launcher
• Create karma.conf.js (Karma config file):
• Run tests: npx karma start

module.exports = function(config) {
  config.set({
    frameworks: ["jasmine"], // use Jasmine
    files: [
      "math.js",
      "math.spec.js"
    ],
    browsers: ["Chrome"], // run tests in Chrome
    singleRun: true
  });
};

module.exports = function(config) {
  config.set({
    frameworks: ["jasmine"], // use Jasmine
    files: [
      "math.js",
      "math.spec.js"
    ],
    browsers: ["Chrome"], // run tests in Chrome
    singleRun: true
  });
};

Karma will open Chrome, run your Jasmine tests, and report results in the terminal.

✅ Summary:

• Jasmine → used to write tests (assertions, test suites).
• Karma → used to run tests (in browsers, CI/CD, automated runs).