Gherkin Expert Skill

Purpose

Provides expert-level Gherkin/BDD specification assistance for writing behavioral scenarios that clarify acceptance criteria and improve downstream code generation quality.

When This Skill Activates

• User asks to write or review Gherkin feature files or scenarios
• User needs help structuring complex acceptance criteria
• User wants to translate business requirements into Given/When/Then format
• User asks about BDD methodology or scenario design
• User wants behavioral specifications for multi-actor or multi-step workflows
• User mentions Cucumber, SpecFlow, or BDD frameworks
• User is working on features with complex acceptance criteria that would benefit from structured scenarios

How It Works

This skill delegates to the gherkin-expert agent which has knowledge of:

1. Gherkin syntax and idioms — Feature/Scenario/Given/When/Then, backgrounds, scenario outlines, data tables, tags
2. BDD methodology — discovery workshops, living documentation, specification by example
3. Scenario design — single-behavior focus, declarative style, avoiding implementation details
4. Domain modeling — ubiquitous language, bounded contexts expressed through scenarios
5. AI prompt improvement — using Gherkin specs as prompt context for better code generation (empirically validated: +26% over English-only)

When Gherkin Adds Value (Judgment Call)

Gherkin is a tool, not a rule. Use judgment:

Good fit:

• Complex multi-step behavioral requirements with many edge cases
• Multi-actor scenarios (user does X, system responds Y, admin sees Z)
• Business rules with combinatorial conditions (scenario outlines)
• Acceptance criteria that stakeholders need to validate
• Features where "what done looks like" is ambiguous in English

English is fine:

• Simple CRUD operations with obvious behavior
• Internal tooling with a single developer as audience
• Config changes, styling, documentation
• Requirements where the hard part is algorithm design, not behavior specification

Usage Examples

# Write scenarios for a feature
/gherkin-expert Write Gherkin scenarios for our user authentication flow

# Review existing scenarios
/gherkin-expert Review these acceptance criteria for completeness

# Translate requirements to BDD
/gherkin-expert Convert these business rules into Given/When/Then scenarios

# Decide if Gherkin is appropriate
/gherkin-expert Should I write Gherkin scenarios for this retry cascade feature?

# Improve scenarios
/gherkin-expert These scenarios feel too implementation-focused, help me make them declarative

Key Resources

• Gherkin experiment results: experiments/hive_mind/gherkin_v2_recipe_executor/
• Issue #3939: Formal specification integration roadmap
• Gherkin reference: https://cucumber.io/docs/gherkin/reference/