test-driven-development

Test-driven development prevents regressions by requiring a failing test before writing production code, creating a safety net that validates intended behavior during future feature work and refactors.

The red-green-refactor cycle in TDD formalizes test-first development by starting with a failing test, implementing minimal code to pass it, and then refining the design to ensure correctness and quality.

To start test-first coding, write a failing test for the intended behavior, then implement the minimal production code required to make that test pass, ensuring quality assurance through explicit expectations.

Yes, test-driven development applies to bug fixes and refactoring across software projects, guiding design and ensuring test coverage by validating the intended behavior through minimal, real tests.

You should avoid test-first development when requirements are ambiguous or exploratory, as TDD relies on tests as the single source of truth for behavior, which requires clear expectations before coding begins.