test-driven-development

Test-driven development guides feature implementation by enforcing a test-first workflow where you write a failing unit test before any production code. This ensures code is written only to satisfy tests, reducing defects and preventing untested code from entering production.

The red-green-refactor cycle in software testing is a workflow where you write a failing test, implement the minimal production code required to pass that test, and then refactor the code while keeping all tests green to ensure codebase stability.

You apply unit tests to fix bugs by first writing a failing test that reproduces the specific bug, then implementing the minimal code to pass the test. This test discipline ensures the bug is resolved and prevents future regressions.

Yes, you can use test-driven development for refactoring existing code. The workflow ensures you keep all unit tests green while you clean up and restructure the codebase, verifying that functional behavior remains stable throughout the refactoring process.

You should not use a test-first workflow for exploratory prototyping where requirements are highly volatile and unknown. The approach requires clear enough specifications to design meaningful failing unit tests before committing to implementation.