test-driven-development

The Test-Driven Development (TDD) Red-Green-Refactor cycle involves writing a failing test, creating minimal code to pass it, and then refactoring. This iterative process ensures all production code is preceded by a failing test to guarantee robustness and prevent regressions.

To start writing code for a new feature using Test-Driven Development, always write a failing test first that defines the expected behavior. Then write the minimal implementation code required to make that specific test pass before proceeding to the refactoring stage.

Yes, Test-Driven Development is fully applicable to both bug fixes and refactoring existing code. It requires writing a failing test that reproduces the bug or validates the refactored behavior, ensuring changes do not introduce regressions and maintain strict code quality.

You should write a failing test before production code to enforce a strict test-first approach. This guarantees the code meets requirements immediately, prevents bugs, and stops unnecessary implementation code from being written without a prior failing test to validate its purpose.

Implementation code written without a prior failing test violates strict Test-Driven Development protocols. The methodology requires adherence to this testing discipline and mandates the deletion of any production code written without a preceding failing test to ensure quality.