Unit testing is a specialized skill that involves testing individual units of code to ensure that they behave as expected before they are integrated into a larger system. This type of testing requires expertise in programming, testing methodologies, and tools used for testing. Test cases are written to verify various scenarios and edge cases, and results are analyzed to identify defects or issues that need to be resolved before the code is released. Successful unit testing helps to ensure that software is reliable, maintainable, and performant.