What role do tests play in Test-Driven Development according to the content?

In Test-Driven Development (TDD), tests primarily serve the crucial role of verifying the correctness of the code. When developers write tests before the actual code, those tests define the expectations and behaviors that the code must fulfill. This process ensures that once the code is written, it can be executed against the tests to check whether it behaves as intended.

This method not only helps in identifying bugs early in the development process but also assists developers in ensuring that the intended functionalities are implemented correctly. If a test fails after a code change, it indicates that something has gone wrong, prompting further investigation and adjustments. This cycle of writing tests, developing code, and continuously running tests builds a robust safety net for maintaining code quality throughout the software development lifecycle.

While tests can indeed provide documentation or user experience insights, those aspects are secondary to their primary purpose of ensuring that the code works correctly as defined by the tests.