Introduction
Functional testing is one of the most important concepts in software testing. Every QA engineer must clearly understand how functional testing works in real-world projects.
What is Functional Testing?
Functional testing verifies that the application works according to the defined business requirements. It focuses on testing features, workflows, and system behavior.
- Is login working?
- Is payment processed successfully?
- Are validation messages correct?
- Is data stored properly in the database?
Objectives of Functional Testing
- Validate business requirements
- Ensure features work correctly
- Verify input and output behavior
- Identify defects in functionality
Types of Functional Testing
- Unit Testing
- Integration Testing
- System Testing
- Acceptance Testing
- Regression Testing
- Smoke Testing
- Sanity Testing
Functional Testing Process
- Understand requirements
- Create test scenarios
- Write test cases
- Prepare test data
- Execute test cases
- Report defects
- Retest and regression
Real-World Examples
Example 1: Login Page Testing
- Enter valid credentials → User should login successfully
- Enter invalid password → Proper error message displayed
Example 2: E-commerce Checkout
- Add product to cart
- Proceed to payment
- Verify order confirmation
Advantages of Functional Testing
- Ensures product quality
- Improves customer satisfaction
- Detects bugs early
- Supports business validation
Functional Testing Interview Questions
What is functional testing?
Functional testing validates application features against requirements.
Is regression testing part of functional testing?
Yes. Regression testing ensures existing functionality works after updates.
What is difference between functional and non-functional testing?
Functional testing checks "what the system does" while non-functional testing checks "how well the system performs".
Frequently Asked Questions
Is functional testing manual or automated?
It can be performed both manually and using automation tools.
Why is functional testing important?
Because it ensures the system meets business requirements.