test-driven-development

To start writing tests before code, define the expected behavior of a new function with a failing test, then write the minimal code required to make it pass. This ensures robust software by preventing regressions and clarifying desired behavior from the start.

The Red-Green-Refactor cycle is a test-driven development process where you first write a failing test, implement the minimal code to make it pass, and then refactor the code. It enforces rigorous testing and prevents future regressions.

To prevent code regressions when adding new features, enforce test-driven development by writing a failing test that defines the expected behavior before writing any production code. This verifies the feature works as intended immediately.

Test-driven development supports existing code refactoring by ensuring all changes are preceded by a failing test. You write tests to verify desired behavior, then refactor the code to pass these tests, maintaining robust and verifiable software.

You should avoid test-driven development when exploring experimental prototypes where behavior is undefined, as the methodology requires writing a failing test to clarify expected behavior before writing any production code.