tdd

Tests verify behavior through public interfaces, not implementation details. Code can change entirely; tests shouldn't. A good test reads like a specification — "user can checkout with valid cart" tells you exactly what capability exists. These tests survive refactors because they don't care about internal structure.

DO NOT write all tests first, then all implementation. This is "horizontal slicing" — treating RED as "write all tests" and GREEN as "write all code."

Correct approach: Vertical slices via tracer bullets. One test → one implementation → repeat. Each test responds to what you learned from the previous cycle.

使用垂直切片示踪子彈工作流程指導測試驅動的開發。在實現功能、修復錯誤或編寫應驅動設計的測試時使用。透過公共介面強制編碼前進行規劃、增量紅綠重構週期以及基於行為的測試。觸發器：「TDD」、「先測試」、「編寫測試」、「追蹤子彈」或透過測試實現增量功能。 來源：sadiksaifi/agents。