Which type of testing focuses primarily on verifying individual units or code modules?

• A. Integration Testing
• B. Unit Testing
• C. Functional Testing
• D. System Testing

Answer: (B)

Unit testing is a crucial stage in the software development process that aims specifically at verifying the functionality of individual units or components of code, often functions or methods. This type of testing is typically performed by developers during the development phase and focuses on ensuring that each piece of code behaves as expected under various conditions.

Unit tests are designed to isolate each component or module, allowing developers to identify bugs at an early stage, thus facilitating easier debugging and a more efficient development process. By catching defects early, unit testing contributes to a more robust and reliable codebase. It sets a foundation upon which subsequent testing types, such as integration testing and system testing, can build, as they typically require a functioning set of modules or components to understand how they interact with one another.

In this context, integration testing examines the interactions between multiple components rather than individual units. Functional testing assesses the software against functional requirements, focusing on user scenarios, while system testing evaluates the entire system’s compliance with specified requirements and behaviors. Therefore, unit testing stands apart due to its specific focus on the functionality of single code units, making it essential for ensuring high code quality and reliable software development.