Test-Driven Development (TDD)

A software development practice where tests are written before the production code they test. The TDD cycle follows three steps: Red (write a failing test that describes the desired behavior), Green (write the minimum code needed to make the test pass), and Refactor (improve the code while keeping tests green). TDD encourages writing only as much code as needed to satisfy requirements, resulting in leaner designs and higher test coverage. It also makes acceptance criteria executable — automated tests directly verify the behaviors described in the user story. While TDD has a learning curve, teams that adopt it consistently report fewer bugs, faster debugging, and greater confidence in making changes.