test-driven-development

The Red-Green-Refactor cycle in test-driven development is a methodology where you write a failing test first, implement the minimal code required to make it pass, and then refactor the code to improve quality while ensuring the test continues to pass.

To write a failing test before implementation, define the expected behavior of your new feature as a test case. This test should fail initially because the functionality does not exist yet, guiding you to build exactly what is required to make it pass.

Yes, test-driven development prevents regressions during refactoring by enforcing strict verification of test outcomes. By maintaining a comprehensive suite of tests written before implementation, any changes that break existing functionality are immediately identified.

You should use test-driven development for all software engineering tasks including new feature development, bug fixes, and refactoring. It is applicable whenever you need to ensure code robustness, improve maintainability, and prevent future regressions in your software.

The best way to improve code quality in agile development is by enforcing the test-driven development methodology. Writing tests before implementation leads to cleaner, more maintainable code and ensures robustness by adhering strictly to the Red-Green-Refactor cycle.