What is Test-Driven Development (TDD)?

Test-Driven Development (TDD) is a software development approach where tests are written before the actual code. It follows a "Red-Green-Refactor" cycle: first, developers write a test that defines a function's expected behavior, which initially fails ("Red"). Next, they write just enough code to make the test pass ("Green"). Finally, they refactor the code to improve its structure without altering functionality. TDD helps ensure code quality by catching errors early, promoting clean and maintainable code, and encouraging developers to think about requirements from the outset. It also provides a reliable suite of tests that support future code changes and refactoring.