BDD & Gherkin Specification

You are an expert in Behavior-Driven Development (BDD) and Gherkin specification writing. This skill helps you create clear, executable specifications that bridge business requirements and technical implementation.

What is BDD?

BDD is a methodology for capturing requirements that expresses the behavior of features using real-world examples. It bridges the gap between business stakeholders, developers, and testers by using shared language and concrete scenarios.

What is Gherkin?

Gherkin is a plain-text language for writing BDD scenarios using keywords like Feature, Scenario, Given, When, Then. It's human-readable, business-focused, and executable as automated tests.

When to Use This Skill

USE when:

• Defining acceptance criteria for user stories
• Creating living documentation
• Bridging communication gaps between technical and non-technical stakeholders
• Specifying complex business rules
• Working in cross-functional teams

DO NOT USE when:

• Requirements are purely technical (architecture, refactoring)
• Team is small and co-located with constant communication
• Features are too simple to warrant formal specification

Quick Start

Basic Gherkin Structure:

Feature: User Login

  Scenario: Successful login with valid credentials
    Given the user is on the login page
    When the user enters valid credentials
    Then the user should be redirected to the dashboard

Available Resources

Core Documentation

• gherkin-syntax.md - Complete Gherkin language reference

  • Basic structure and file naming
  • Given-When-Then detailed explanation
  • All keywords (Feature, Scenario, Background, Scenario Outline, Rule)
  • AND/BUT usage
  • Read when: Writing your first feature file or need keyword reference

• best-practices.md - Writing effective scenarios

  • Declarative vs imperative style
  • Keep scenarios focused and independent
  • Consistent language and perspective
  • Clear outcomes and business value
  • Read when: Reviewing or improving scenario quality

• examples.md - Real-world feature file examples

  • Complete feature files across different domains
  • Product search, shopping cart, authentication
  • Background and Scenario Outline usage
  • Side-by-side comparisons (good vs bad)
  • Read when: Need inspiration or want to see patterns in action

Advanced Topics

• anti-patterns.md - Common mistakes and how to avoid them

  • Testing implementation vs behavior
  • Overly technical language
  • Dependent scenarios
  • UI-centric vs behavior-centric
  • Read when: Troubleshooting or code review

• organization.md - Structuring large feature file suites

  • Directory structure patterns
  • When to split features
  • Using Rules to group scenarios
  • Team collaboration patterns
  • Read when: Setting up project structure or scaling BDD adoption

• quick-reference.md - Cheat sheet and templates

  • Feature file template to copy
  • Keywords at a glance
  • Common patterns
  • Quick decision tree
  • Read when: Need fast lookup or reminder

Key Principles

1. Be Declarative - Describe WHAT behavior should happen, not HOW it's implemented
2. Stay Focused - One scenario = one behavior (5-10 steps max)
3. Stay Independent - Scenarios should not depend on each other
4. Use Business Language - Avoid technical jargon; speak the user's language
5. Make it Readable - Anyone on the team should understand the scenario

Typical Workflow

1. Start with Examples - Read examples.md to see patterns
2. Learn Syntax - Reference gherkin-syntax.md for keywords
3. Write Scenarios - Use quick-reference.md template
4. Review Quality - Check against best-practices.md
5. Avoid Mistakes - Scan anti-patterns.md during review

Quick Tips

• Write scenarios BEFORE code (they're specifications, not tests)
• Each scenario should be understandable in isolation
• Use Background for common setup across scenarios
• Use Scenario Outline for testing multiple similar cases
• Use Rule to group related scenarios
• Keep feature files under 20 scenarios (split if larger)

File Naming Convention

Use lowercase with underscores: user_authentication.feature, shopping_cart_checkout.feature

Remember

BDD scenarios are conversations written down, not test scripts. They should be readable by product owners, developers, and testers alike. If your scenario requires technical knowledge to understand, it's not declarative enough.

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For comprehensive guidance, explore the reference/ directory based on your current need.