Agent skill
bdd-patterns
Use when applying Behavior-Driven Development patterns including Given-When-Then structure, feature files, and acceptance criteria. Use when writing BDD-style tests and specifications.
Install this agent skill to your Project
npx add-skill https://github.com/TheBushidoCollective/han/tree/main/plugins/patterns/bdd/skills/bdd-patterns
SKILL.md
BDD Patterns
Master Behavior-Driven Development patterns to write clear, business-readable specifications that drive implementation.
Given-When-Then Structure
The fundamental BDD pattern uses three parts:
- Given: The initial context or preconditions
- When: The action or event being tested
- Then: The expected outcome or result
Feature: User Authentication
Scenario: Successful login with valid credentials
Given a registered user with email "user@example.com"
And the user has password "secure123"
When the user submits the login form with correct credentials
Then the user should be redirected to the dashboard
And a session should be created
Feature File Organization
Feature: Shopping Cart
As a customer
I want to manage items in my cart
So that I can purchase products I'm interested in
Background:
Given I am logged in as a customer
And the product catalog is available
Scenario: Add item to empty cart
Given my cart is empty
When I add "Blue T-Shirt" to my cart
Then my cart should contain 1 item
And the cart total should be $29.99
Scenario: Remove item from cart
Given my cart contains "Blue T-Shirt"
When I remove "Blue T-Shirt" from my cart
Then my cart should be empty
Scenario Outlines for Data-Driven Tests
Scenario Outline: Password validation
Given I am on the registration page
When I enter password "<password>"
Then I should see "<message>"
Examples:
| password | message |
| abc | Password too short |
| abcdefgh | Password needs a number |
| abcdefgh1 | Password accepted |
| abcdefgh1! | Password accepted |
Step Definition Patterns
# Ruby/Cucumber example
Given('a registered user with email {string}') do |email|
@user = User.create!(email: email, password: 'password123')
end
When('the user submits the login form with correct credentials') do
visit login_path
fill_in 'Email', with: @user.email
fill_in 'Password', with: 'password123'
click_button 'Log In'
end
Then('the user should be redirected to the dashboard') do
expect(page).to have_current_path(dashboard_path)
end
When to Use This Skill
Use bdd-patterns when you need to:
- Write acceptance tests that stakeholders can understand
- Define behavior before implementation
- Create living documentation from tests
- Bridge communication between developers and business
- Ensure features meet business requirements
Best Practices
- Write scenarios from the user's perspective
- Keep scenarios focused on single behaviors
- Use declarative language, not implementation details
- Reuse step definitions across scenarios
- Use Background for common setup steps
- Keep feature files organized by domain area
Common Pitfalls
- Writing scenarios that are too technical
- Coupling steps to specific UI implementations
- Creating overly complex scenario outlines
- Not maintaining feature files as code changes
- Mixing multiple behaviors in one scenario
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