tdd

Enforce test-driven development by applying the red-green-refactor loop with vertical-slice tracer bullets that validate behavior through public interfaces, ensuring tests survive refactoring. This disciplined workflow guides end-to-end cycles from planning through implementation to refactoring.

Vertical-slice testing in TDD workflows means writing end-to-end tracer bullets that validate behavior through public interfaces rather than testing implementation details horizontally, ensuring tests remain durable and survive refactoring. This approach validates complete feature paths.

Write tests that survive refactoring by verifying observable behavior through public interfaces rather than implementation details, following structured TDD workflow documentation that emphasizes deep modules and interface design. This ensures tests remain valid across code changes.

Mocking guidelines for test-driven development are included as sub-documents covering deep modules, interface design, mocking, and refactoring practices. These guidelines help structure tests around public interfaces while maintaining disciplined TDD cycles.

Start a TDD cycle for feature development by writing one tracer bullet test against a public interface and implementing the minimal code needed to pass, following vertical-slice workflows from planning through refactor. This establishes end-to-end behavior validation early.

Vertical-slice testing may not suit projects where end-to-end public interfaces are undefined or when horizontal layer testing is specifically required for isolated component validation. The approach emphasizes behavioral validation through complete feature paths rather than unit-level isolation.