test-driven-development

Test-driven development fixes bugs by writing a failing reproduction test that proves the bug exists, then applying the minimal code fix to make the test pass and prevent regressions.

The red-green-refactor cycle in unit testing is a test-driven workflow where you write a failing test, implement the minimal code to pass it, and then refactor to improve code quality while maintaining passing tests.

To start writing tests before implementing features, define the expected behavior by writing a failing unit test first, then develop the exact logic required to make that test pass, ensuring correctness from the start.

Test-first development applies to refactoring by writing tests that capture the current intended behavior and edge cases, ensuring your structural improvements do not introduce regressions into the codebase.

Test-driven development works across any codebase without specific framework dependencies, using universal red-green-refactor cycles to drive code quality through test automation and documented expectations.