- name
- bdd
- scope
- partial
- description
- [UDS] Reference for Behavior-Driven Development: Gherkin Given-When-Then format and Three Amigos structure.
Use when: writing or reviewing .feature scenarios, choosing ubiquitous language, running a discovery conversation about behaviour.
Not for: executing the BDD lifecycle or RED/GREEN automation — that moved to the adoption layer (XSPEC-095); turning .feature files into E2E skeletons — use /e2e.
Keywords: BDD, Gherkin, Given When Then, feature file, scenario, Three Amigos, 行為驅動開發, 場景, 特性檔.
- allowed-tools
- Read, Write, Grep, Glob
- argument-hint
- [feature or spec | 功能或規格]
- status
- reference
<!-- DEPRECATION NOTICE (XSPEC-086 Phase 4, 2026-04-28):
BDD lifecycle orchestration (4-phase cycle, Gherkin scaffolding, RED/GREEN execution) relocated to
adoption layer (XSPEC-095, 2026-04-28). This Skill retains: Gherkin format definition, Three
Amigos structure, BDD cycle diagram.
For enforced lifecycle execution, use your adoption layer's toolchain.
-->
# BDD Assistant | BDD 助手
> ⚠️ **Status: Reference(參考用,非可執行流程)** — BDD 生命週期協調(4 階段循環、Gherkin scaffolding、RED/GREEN 執行)已於 2026-04-28 移至 **adoption layer(XSPEC-095)**。此處保留 Gherkin 格式定義、Three Amigos 結構、BDD 循環圖供參考。
> 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 Behavior-Driven Development (BDD) workflow using Given-When-Then format.
引導行為驅動開發(BDD)流程,使用 Given-When-Then 格式。
## BDD Cycle | BDD 循環
```
DISCOVERY ──► FORMULATION ──► AUTOMATION ──► LIVING DOCS
^ │
└────────────────────────────────────────────┘
```
## 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.
### 1. DISCOVERY - Explore Behavior | 探索行為
Discuss with stakeholders, identify examples and edge cases, understand the "why".
### 2. FORMULATION - Write Scenarios | 制定場景
Write Gherkin scenarios using ubiquitous language, make them concrete and specific.
### 3. AUTOMATION - Implement Tests | 自動化測試
Implement step definitions, write minimal code to pass, follow TDD within automation.
### 4. LIVING DOCUMENTATION - Maintain | 活文件維護
Keep scenarios current, use as shared documentation, review with stakeholders.
## Gherkin Format | Gherkin 格式
```gherkin
Feature: User Login
As a registered user
I want to log in to my account
So that I can access my dashboard
Scenario: Successful login
Given I am on the login page
When I enter valid credentials
Then I should see my dashboard
```
## Three Amigos | 三劍客會議
| Role | Focus | 角色 | 關注點 |
|------|-------|------|--------|
| **Business** | What & Why | 業務 | 什麼和為什麼 |
| **Development** | How | 開發 | 如何實現 |
| **Testing** | What if | 測試 | 假設情況 |
## Usage | 使用方式
```
/bdd - Start interactive BDD session | 啟動互動式 BDD 會話
/bdd "user can reset password" - BDD for specific feature | 針對特定功能
/bdd login-feature.feature - Work with existing feature file | 處理現有功能檔案
```
## Next Steps Guidance | 下一步引導
After `/bdd` completes, the AI assistant should suggest:
> **BDD 場景已定義。建議下一步 / BDD scenarios defined. Suggested next steps:**
> - 執行 `/tdd` 實作步驟定義 ⭐ **Recommended / 推薦** — Implement step definitions
> - 執行 `/checkin` 品質關卡(若功能完成)— Quality gates (if feature complete)
> - 與利害關係人審查場景確保業務正確性 — Review scenarios with stakeholders
## Reference | 參考
- [BDD Workflow Guide](./bdd-workflow.md) — Read it when running discovery, formulation and automation as a cycle.
- [Gherkin Quick Reference Guide](./gherkin-guide.md) — Read it when writing Given/When/Then and you need the exact syntax.
- Detailed guide: [guide.md](./guide.md)
- Core standard: [behavior-driven-development.md](../../core/behavior-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:[`/bdd`](../commands/bdd.md#ai-agent-behavior--ai-代理行為)
>
> For complete AI agent behavior definition, see the corresponding command file: [`/bdd`](../commands/bdd.md#ai-agent-behavior--ai-代理行為)
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