🧪 Introduction to JavaScript Testing

Testing ensures your code works as expected, prevents bugs, and boosts confidence when refactoring or adding new features.

📌 Why Test Your Code?

• Detect bugs early
• Ensure consistent behavior
• Enable safe refactoring
• Document expected functionality

🔍 Types of Tests

• Unit Tests: Test individual functions or modules
• Integration Tests: Check how modules work together
• End-to-End Tests: Simulate real user interaction (e.g., clicking buttons)

⚙️ Writing a Simple Unit Test

Let’s test a basic function:

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

// test
const result = add(2, 3);
console.assert(result === 5, 'Expected 2 + 3 to equal 5');

This test will only log an error if it fails. You can run it directly in the browser or Node.js console.

🧰 Testing Frameworks

• Jest – Great for unit and integration testing
• Mocha + Chai – Flexible and powerful
• Vitest – Fast Jest-compatible runner (used with Vite)
• Cypress – End-to-end testing for UIs

📁 File Structure Example

project/
├── src/
│   └── math.js
├── tests/
│   └── math.test.js