test-driven-development

Test-driven development in JavaScript requires writing a failing unit test before implementing code, then writing minimal code to pass it, and finally refactoring safely. This Red-Green-Refactor cycle ensures correctness and prevents regressions.

The Red-Green-Refactor cycle is a test-driven development process where you write a failing test, implement minimal code to make it pass, and then refactor while maintaining passing test suites. It drives reliable code by confirming behavior first.

Yes, test-driven development is ideal for bug fixes and refactoring tasks. You write failing unit tests that capture the desired behavior or bug condition, then adjust code until tests pass, ensuring changes don't introduce new regressions.

Writing failing tests before implementing TypeScript code confirms the correct behavior is missing initially. This prevents wasted effort on incorrect implementations and ensures the final code accurately meets the specified requirements.

Common TDD anti-patterns include skipping the failing test step or writing tests that pass immediately without implementation. This skill provides checklists to validate tests truly fail first and warns against shortcuts that compromise unit testing reliability.