test-driven-development

Test-driven development starts by writing a minimal failing unit test that defines the intended behavior. You then implement the minimal production code to pass the test, and run the full test suite to verify no regressions.

The Red Green Refactor loop is a test-first workflow where you write a failing test, verify it fails for the right reason, implement minimal code to pass the test, then refactor while keeping the test suite green.

To reproduce a bug fix with a failing test, write a test that demonstrates the incorrect behavior, confirm the specific failure is real and not an error, implement the minimal fix, and run the full test suite to prevent regressions.

Test-first workflows are required for refactors and behavior changes to ensure features and fixes are validated before production code exists. You write a failing test, implement minimal changes to pass, and keep the test output clean.

Expected failures in test-driven development must be real failures, not errors. This verification ensures your minimal failing test correctly defines the intended behavior before you implement any production code to satisfy it.

Test-driven development applies to both unit and integration testing workflows. It enforces a test-first discipline across new features, bug fixes, refactors, and behavior changes to ensure production code is validated before it exists.