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Use when writing or improving Gherkin .feature files, after business rules and examples have been discovered
Codex または Claude でインストール この Prompt をコピーして Codex、Claude、または他のアシスタントに貼り付けると、Skill ページを確認してインストールできます。
SOC 職業分類に基づく
| name | designing-bdd-scenarios |
| description | Use when writing or improving Gherkin .feature files, after business rules and examples have been discovered |
Structure discovered examples as executable Gherkin. Covers Background, Scenario Outline + Examples, and scenario writing rules.
Prerequisite: discovering-bdd-scenarios — rules and examples must be known before structuring.
Core principle: Representative selection over exhaustive enumeration.
| Rule | Check |
|---|---|
| One scenario, one behavior | Split multi-behavior scenarios |
| Declarative, not imperative | Business outcomes, not UI/API/HTTP details |
| Concrete examples | Specific values ("$500", "17 ans"), not abstractions |
| Short (3-5 steps) | Longer = testing multiple behaviors |
| Background for shared Given | Factorize repeated preconditions only |
Scenarios describe external observables only:
| ❌ Forbidden | ✅ Allowed |
|---|---|
| Class names, method names | Business actions and actors |
| HTTP endpoints, status codes | Business outcomes |
| Repository, database tables | Data in business terms |
| ❌ BAD (implementation) | ✅ GOOD (business outcome) |
|---|---|
POST /api/eligibility returns 200 | Eligibility request is accepted |
EligibilityHandler returns rejected | Driver is refused for being too young |
Contexte:
Étant donné nous sommes le "01/01/2026"
Only Given steps. Never When/Then.
Plan du Scénario: Vérification de l'âge minimum
Étant donné un conducteur âgé de <age> ans
Et le véhicule est une "<vehicule>"
Quand je demande une éligibilité
Alors la demande est <resultat>
Exemples: Conducteurs refusés
| age | vehicule | resultat |
| 17 | Voiture | refusée avec le motif "Conducteur trop jeune pour ce véhicule" |
Exemples: Conducteurs acceptés
| age | vehicule | resultat |
| 18 | Voiture | acceptée |
Group Examples by intent (accepted vs rejected), not by data shape.
Use outlines for boundary conditions. Avoid when scenarios diverge structurally.
Use when Given steps are unique and not shared with other scenarios.
Per business rule, target 3-4 cases (not 10+):
| Type | Count | Target |
|---|---|---|
| Happy path | 1 | Most common success |
| Key alternatives | 1-2 | Boundary values, rejections |
| Error path | 1+ | Target 40%+ of total scenarios |
For each threshold, test both sides:
| Rule | Below boundary | At boundary | Above boundary |
|---|---|---|---|
| Age ≥18 | 17 (rejected) | 18 (accepted) | — |
| Power >100ch | 100 (accepted) | — | 101 (rejected) |
Clarify the operator (≥ vs >) before writing scenarios.
| Mistake | Fix |
|---|---|
| Exhaustive enumeration (20+ scenarios) | Select representative examples per rule |
| No Background | Factorize shared Given steps |
| Individual scenarios for boundary variations | Use Scenario Outline + Examples |
| Only rejection scenarios, no acceptance | Include Golden Path per rule |
| Boundary operator ambiguous | Clarify with boundary pair (100ch OK, 101ch KO) |
| Implementation details in titles or steps | Business language only — spec-leakage rule |
| Proceeding without explicit approval | Present scenarios, wait for explicit validation |
REQUIRED: discovering-bdd-scenarios — run first to discover rules and examples
PAIRS WITH: outside-in-tdd — scenarios feed acceptance tests
PAIRS WITH: red-synthesize-green — TDD cycle after approval
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