What is the primary focus of a unit test?

The primary focus of a unit test is on testing small, functional components of an application. Unit tests are designed to validate that each individual piece of code, usually a function or method, works as intended. By isolating each unit of code, developers can easily identify any errors or bugs within that specific component, ensuring that it behaves correctly in terms of input and output.

Unit tests are fundamental in the software development process as they promote better code quality and maintainability. They allow for early detection of issues, which can save time and costs in the long run, and encourage a test-driven development (TDD) approach, where tests are created before the code itself. This methodology emphasizes the importance of small, manageable tests that focus on specific functionality rather than the entire system or application, which is the hallmark of effective unit testing.