test-driven-development

To start test-driven development, write one failing test that specifies a public behavior, then implement the minimal code to pass it. Repeat this red-green-refactor loop incrementally to build reliable software features.

A tracer bullet workflow in agile software testing drives minimal implementation through a single end-to-end test cycle. It validates public interfaces early by connecting system endpoints before fleshing out internal logic.

To refactor code safely, use incremental refactor discipline guided by tests that preserve observable behavior. Public-interface driven tests validate real behavior, ensuring internal implementation changes do not break existing functionality.

In TDD, you should test public interfaces rather than internal implementation details. Testing through public APIs exercises real behavior without internal mocks, keeping tests stable and resilient during code evolution.

Test-driven development does not require mocking for feature planning. It integrates planning, feedback loops, and checklists to reduce risk, relying on public-interface tests rather than internal mocks to enforce guardrails.

Avoid the red-green-refactor TDD loop when delivering throwaway prototypes or exploratory spikes where stable public interfaces are undefined. Without a target public behavior to specify, the strict test-first cycle adds unnecessary overhead.