test-driven-development

Test-driven development begins by writing a failing test that pins expected behavior, implementing minimal code to pass the test, and then refactoring safely while keeping all tests green. Describe the feature request first to guide the test logic.

The red-green-refactor cycle is a unit testing pattern where you first write a failing test (red), implement minimal code to pass it (green), and then safely refactor the code while ensuring tests remain green. It enforces correctness before implementation.

Test-driven development is applicable during bug fixes and behavioral changes across existing codebases. You write a failing test that reproduces the bug, implement the fix to pass the test, and prevent future regressions by keeping the test green.

This test-driven development approach documents testing patterns like the Prove-It approach and the testing pyramid to guide QA. These patterns ensure you prove correctness with tests before implementation to prevent regressions.

A tests-first approach is less suitable for exploratory coding or spike solutions where behavior is undefined. Since test-driven development requires pinning expected behavior with a failing test first, it works best for new features, bug fixes, and defined behavioral changes.