What Is Functional and Non Functional Testing?

The two major categories of software testing consist of functional and non-functional testing which serve unique purposes for assuring application quality and reliability.

Functional Testing

Software functional testing ensures each program component meets its specified operational requirements. The process validates specific application features as well as individual functions to check they work correctly.

Key Characteristics:

• Focus: It checks "what" the system does, validating specific functionalities like input validation, user interface operations, and database interactions.
• Types: Includes unit testing, integration testing, system testing, and acceptance testing. Examples include checking login functionality and verifying business logic.
• Execution: Can be performed manually or through automated testing tools. It is typically conducted before non-functional testing.

Non-Functional Testing

Non-functional testing assesses aspects of the software that are not related to specific functions but are critical for overall performance and user satisfaction. This includes evaluating performance, usability, reliability, and security.

Key Characteristics:

• Focus: It addresses "how" the system performs under various conditions, ensuring it meets quality standards beyond just functionality.
• Types: Includes performance testing, load testing, stress testing, usability testing, and security testing. For example, checking how many users can log in simultaneously or measuring response times.
• Execution: Generally requires automated tools due to its complexity and is performed after functional testing.