test-driven-development

Test-driven development (TDD) is a disciplined approach where you write a failing test first, then implement minimal code to pass it, then refactor. This ensures requirements are captured in automated tests before production code exists, preventing bugs and clarifying behavior upfront.

Red-Green-Refactor is a structured TDD process: write a failing test (Red), implement minimal code to pass it (Green), then improve the code without breaking tests (Refactor). Repeat this cycle for each feature, bug fix, or behavior change to maintain code quality.

Yes. TDD applies to new features, bug fixes, refactoring, and behavior changes. For each task, write a failing test first that captures the requirement, implement the minimal code to satisfy it, then refactor with all tests passing to ensure correctness.

Test-first development (TDD) captures requirements before implementation, ensuring no production code executes without a failing test validating it. Writing tests after code often misses edge cases and treats testing as validation rather than design, leading to incomplete coverage and discovered bugs.

The AAA Pattern (Arrange-Act-Assert) structures each test into three clear sections: set up inputs and state (Arrange), execute the code under test (Act), and verify the result (Assert). This naming convention makes tests readable, maintainable, and easier to debug.