# Tdd > [UDS] Reference for Test-Driven Development: the Red-Green-Refactor cycle, FIRST principles, and Arrange-Act-Assert structure. Use when: writing a failing test before implementation, structuring a test with Arrange-Act-Assert, checking tests against FIRST. Not for: driving the RED/GREEN cycle interactively — that moved to the adoption layer (XSPEC-095); measuring how much code the tests cover — use /coverage. Keywords: TDD, test first, Red Green Refactor, FIRST, Arrange Act Assert, unit test, 測試驅動開發, 紅綠重構, 單元測試. - Skill: `asiaostrich/tdd` (Agent Skill, multi-file: 4 files) - Install (CLI): `npx skillmds@latest add asiaostrich/tdd` - Raw SKILL.md: https://api.skillmd.com/api/skills/asiaostrich/tdd/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: AsiaOstrich (https://skillmd.com/u/asiaostrich) - Updated: 2026-09-10 - Page: https://skillmd.com/skills/asiaostrich/tdd --- # TDD Assistant | TDD 助手 > ⚠️ **Status: Reference（參考用，非可執行流程）** — TDD 流程協調（RED→GREEN→REFACTOR 循環、測試執行 gates）已於 2026-04-28 移至 **adoption layer（XSPEC-095）**。此處保留 TDD 原則、FIRST 規則、AAA 格式、語言範例、流程指南供參考。 > Lifecycle orchestration has moved to the adoption layer (XSPEC-095); this document is **reference-only**. For enforced execution, use your adoption layer's toolchain. Guide through the Test-Driven Development workflow: Red-Green-Refactor. 引導測試驅動開發（TDD）流程：紅-綠-重構。 ## TDD Cycle | TDD 循環 ``` ┌─────┐ ┌───────┐ ┌──────────┐ │ RED │ ────► │ GREEN │ ────► │ REFACTOR │ └─────┘ └───────┘ └──────────┘ ▲ │ └────────────────────────────────┘ ``` ## Workflow | 工作流程 > 📖 以下為流程的**參考結構**，非可執行步驟；自動化／強制執行請用 adoption layer 工具鏈（XSPEC-095）。 > The steps below are a **reference structure**, not an executable workflow. ### Phase 1: RED - Write Failing Test | 紅燈 - 撰寫失敗測試 - Write a test that describes the desired behavior | 撰寫描述預期行為的測試 - Run tests - confirm it **fails** for the right reason | 執行測試 - 確認正確地失敗 - Use AAA pattern (Arrange-Act-Assert) | 使用 AAA 模式 ### Phase 2: GREEN - Make Test Pass | 綠燈 - 讓測試通過 - Write **minimum** code to pass the test | 撰寫最少的程式碼讓測試通過 - Hardcoding is acceptable at this stage | 此階段可以硬編碼 - Run tests - confirm it **passes** | 執行測試 - 確認通過 ### Phase 3: REFACTOR - Improve Code | 重構 - 改善程式碼 - Remove duplication (DRY) | 移除重複 - Improve naming and structure | 改善命名與結構 - Run tests after **every** change | 每次變更後執行測試 - No new functionality added | 不新增功能 ## FIRST Principles | FIRST 原則 | Principle | Description | 說明 | |-----------|-------------|------| | **F**ast | Tests run quickly (< 100ms/unit) | 快速執行 | | **I**ndependent | No shared state between tests | 測試間無共享狀態 | | **R**epeatable | Same result every time | 每次結果相同 | | **S**elf-validating | Clear pass/fail result | 明確的通過/失敗 | | **T**imely | Written before production code | 在產品程式碼之前撰寫 | ## Usage | 使用方式 - `/tdd` - Start interactive TDD session - `/tdd calculateTotal` - TDD for specific function - `/tdd "user can login"` - TDD for user story ## Next Steps Guidance | 下一步引導 After `/tdd` completes, the AI assistant should suggest: > **TDD 循環完成。建議下一步 / TDD cycle complete. Suggested next steps:** > - 執行 `/checkin` 通過品質關卡 ⭐ **Recommended / 推薦** — Pass quality gates > - 執行 `/coverage` 確認測試覆蓋率 — Check test coverage > - 執行 `/code-review` 自我審查程式碼 — Self-review code quality ## Reference | 參考 - [TDD Language Examples](./language-examples.md) — Read it when you need a concrete example in a specific language. - [TDD Workflow Guide](./tdd-workflow.md) — Read it when running the red-green-refactor cycle end to end. - Detailed guide: [guide.md](./guide.md) - Core standard: [test-driven-development.md](../../core/test-driven-development.md) ## AI Agent Behavior | AI 代理行為 > 完整的 AI 行為定義請參閱對應的命令文件：[`/tdd`](../commands/tdd.md#ai-agent-behavior--ai-代理行為) > > For complete AI agent behavior definition, see the corresponding command file: [`/tdd`](../commands/tdd.md#ai-agent-behavior--ai-代理行為)