Functional Testing

📌 Definition:

📖 Detailed Explanation:

Functional testing answers the question: 'Does the system do what it's supposed to do?' You test every feature, every button, every workflow to ensure it behaves correctly. It's the most common type of testing because every software must first be functionally correct before considering performance or security.

📎 Characteristics:

• Focuses on input-output behavior and user workflows
• Does not consider internal code structure or implementation details
• Often categorized as black-box testing (no code knowledge needed)
• Validates what the software does, not how it does it
• Tests both positive scenarios (happy path) and negative scenarios (error handling)

📎 Test Types Under Functional:

• Sanity Testing - Quick smoke test after new build
• Smoke Testing - Verify critical functionality works
• Regression Testing - Ensure changes don't break existing features
• Exploratory Testing - Creative testing without predefined test cases
• End-to-End Testing - Test complete user workflows

📎 Examples:

• Login validation: Correct password grants access, incorrect denies access, account locks after 5 failed attempts
• Form submission: Required fields validation, data saves correctly to database, confirmation email is sent
• E-commerce cart: Add/remove items, apply discount code, calculate tax, complete payment
• API response: GET /api/users returns 200 status with user list in JSON format

📎 Common Tools:

• Selenium
• Cypress
• TestNG
• JUnit
• UFT (Unified Functional Testing)