test-driven-development

The red-green-refactor cycle in test-driven development is a mandatory loop: write a failing test for intended behavior, make the smallest code change to pass it, then refactor safely only after tests pass.

To write unit tests before implementing a new feature, you design interfaces from tests by capturing the intended behavior first, forcing the test to fail, and then writing minimal implementation code to achieve fast feedback and prevent regressions.

Use test-driven development for software refactoring when you need fast feedback and regression prevention across modules, classes, and functions, ensuring that behavior-first changes are verified by passing tests before altering code.

Yes, test-driven development works for fixing bugs without mocks by using real code assertions to design interfaces from tests, ensuring tests remain aligned to observable behavior rather than relying on fragile mock implementations.

The best way to prevent fragile implementations during software development is applying test-driven development to design features around observable behavior, forcing tests to fail first and preventing unverified code from being deployed.

Yes, you can use test-driven development for behavior-driven software changes by writing failing tests first that capture the desired behavior, then applying minimal implementation steps to safely verify features and bugfixes.