tdd

Test-driven development uses the red-green-refactor loop to drive feature implementation safely. You write a failing integration test, implement the minimal code to make it pass, and then refactor while ensuring observable behavior through public interfaces remains unchanged.

To write integration tests that validate behavior without testing implementation details, focus on exercising public interfaces and observable outputs. Discourage tests that assert private state or internal module interactions, ensuring safe refactoring and clearer specifications.

Yes, test-driven development works for refactoring existing code and fixing bugs. Writing targeted integration tests first captures the desired behavior, enabling safe refactors and iterative design while maintaining well-tested, maintainable software projects.

Dependency injection matters for testability in software testing because it promotes mockability and clean interfaces. Injecting dependencies allows you to isolate components during integration testing, ensuring tests validate behavior through public interfaces without coupling to internal implementations.

The best way to start test-driven development for a new feature addition is to implement one targeted integration test capturing the desired behavior. Apply vertical slicing to guide design, then write the minimal code required to make that single test pass.

You should not use test-driven development for software refactoring when the existing code lacks clear public interfaces or cannot support dependency injection. Without mockability and observable behavior boundaries, integration tests cannot effectively guide iterative design or ensure safe refactors.