test-driven-development

Test-driven development starts by writing a failing unit test for the desired behavior in TypeScript, then implementing the minimal production code required to pass that test. This enforces the Red-Green-Refactor cycle to catch design issues early.

The Red-Green-Refactor cycle is a core test-driven development practice where you write a failing test, implement minimal code to make it pass, and then refactor the implementation for cleanliness. It ensures tests fail before production code is written.

Yes, test-driven development applies to bug fixes, refactoring, and behavior changes across JavaScript and TypeScript projects. It ensures correct functionality by requiring a failing test before any production code changes are implemented.

Unit tests must fail before writing production code to verify the test is actually checking the desired behavior. This test-driven development requirement catches design issues early and prevents regressions by ensuring a minimal, verifiable implementation.

The best way to ensure software reliability during behavior changes is enforcing test-driven development. By applying the Red-Green-Refactor cycle, you write failing tests first, implement minimal code, and refactor safely to prevent future regressions.

You should not use the Red-Green-Refactor cycle when verifying already completed behavior without changes, as test-driven development targets new features, bug fixes, and refactoring to ensure tests fail before minimal production code is written.