Which test ensures that a particular block of code performs the exact action intended and provides the exact output expected?

A unit test is specifically designed to validate that a particular block of code, typically a function or method, performs its intended action and produces the expected output. It focuses on a small segment of the code to ensure that it behaves as intended under specified conditions. Unit tests are usually written by developers as they write the code, enabling them to check that each individual component functions correctly before integrating it into larger systems.

This approach is crucial in identifying bugs at an early stage in the development process, as it isolates each part of the program and tests it independently. The primary goal of a unit test is to make sure that the code meets its requirements on a granular level, ensuring reliability and maintainability throughout the software development lifecycle.

Other testing methods serve different purposes. For instance, regression tests check that new code changes haven’t adversely affected existing functionality, while integration tests confirm that different modules or services work together correctly. Solution design, on the other hand, is a part of the planning process in development and does not involve testing code execution or output.