tdd

Test-driven development for public interfaces involves writing one test describing observable behavior, then implementing minimal code to pass. This red-green-refactor cycle ensures tests validate behavior through public APIs rather than internal implementation details.

Vertical-slice TDD uses tracer bullets to validate features end-to-end with minimal scope per cycle. You write a single test for a public interface, implement the code to pass, and commit, ensuring continuous end-to-end validation throughout development.

TDD should not be used for UI code, animations, or certain system-framework interactions. Smoke tests or direct verification are more effective in these scenarios where behavioral outcomes are difficult to capture through public-interface testing.

Yes, TDD targets common components like parsers, serializers, services, data models, and CLI commands. These components typically have clean public interfaces, making them ideal for disciplined test-driven development using one-test-one-implementation cycles.

Deep module structure is emphasized for TDD, where tests verify observable behavior through public interfaces rather than internal structure. This approach maintains one-test-one-implementation discipline while ensuring modules expose clean APIs.