test-driven-development

To start test-driven development for a bug fix, write a failing test that reproduces the bug, implement minimal code to pass it, and then refactor safely. This red-green-refactor sequencing prevents regression.

The red-green-refactor sequence in unit testing means writing a failing test first, implementing minimal production code to make it pass, and then safely refactoring the implementation without changing behavior.

Writing tests before production code prevents unverified implementation by forcing you to define expected behavior first. This reduces false positives from excessive mocking and ensures real behavior verification.

Yes, test-driven development works for refactoring existing software by requiring regression coverage first. You verify current behavior with tests, make minimal changes to pass them, and safely refactor the implementation.

To avoid brittle tests when using mock objects, prioritize testing real code paths and real behavior verification over testing the mocks themselves. This prevents false confidence and ensures your tests validate actual software behavior.