test-driven-development

To start test-driven development, write a minimal failing test that defines the intended behavior for your new feature. Run the test to confirm it fails, implement the simplest code to make it pass, run the full test suite to check for regressions, and refactor while keeping all tests green.

The red-green-refactor workflow is a test-first development discipline where you write a failing test (red), implement the minimal production code to make it pass (green), and then improve the code structure while ensuring tests remain green (refactor).

Yes, test-first development applies to bug fixes, refactors, and behavior changes across codebases. You write a failing test that reproduces the bug or verifies the new behavior, implement the minimal fix to pass it, and run full test suites to prevent regressions.

Test-first development prevents regressions in CI environments by requiring every production change to be backed by a failing test. Running targeted tests confirms expected failures, while full test suites detect integration regressions during continuous integration.

The best way to maintain test hygiene during refactoring is to keep tests green at all times. Run the full test suite after structural changes to ensure behavior remains unchanged, using your existing tests as a safety net to catch regressions immediately.