test-driven-development

Test-driven development reduces debugging time by enforcing test-first development to validate behavior before coding. This catches requirement misinterpretations early and encodes edge cases, preventing defects rather than hunting them later.

The Red-Green-Refactor cycle is the core test-driven development workflow: write a failing test for desired behavior, implement the minimal production code to pass it, then refactor for clarity while preserving behavior.

To write tests first for a bug fix, define a failing test that reproduces the specific defect, implement the minimal production code correction to make it pass, and refactor safely. This validates the fix and prevents future regression.

Test-first development works for refactoring by using tests to encode expected behavior and edge cases. You validate existing functionality with tests first, then refactor the production code while preserving that behavior safely.

TDD applies to feature work, bug fixes, and refactoring across modern software projects in multiple languages and teams. It requires defining failing tests and implementing minimal code, making the workflow broadly applicable.

Test-driven development may not suit exploratory spikes or throwaway prototypes where requirements are undefined. TDD requires defining expected behavior and edge cases upfront, which can slow rapid experimentation when final behavior is unknown.