bdd-principles

# BDD Principles

Master the foundational principles and philosophy of Behavior-Driven Development.

## What is BDD?

Behavior-Driven Development (BDD) is a collaborative software development approach that:

- Bridges the gap between business and technical teams
- Uses concrete examples to describe system behavior
- Creates living documentation that serves as tests
- Focuses on delivering business value
- Promotes shared understanding through conversation

## Core Philosophy

### Discovery > Development > Delivery

**Discovery**: Collaborate to understand requirements

- Hold Three Amigos sessions
- Explore with examples
- Challenge assumptions
- Build shared understanding

**Development**: Implement guided by examples

- Use examples as specifications
- Automate examples as tests
- Follow outside-in TDD

**Delivery**: Validate against real behavior

- Executable specifications provide confidence
- Living documentation stays current
- Regressions are caught early

## The Three Amigos

A practice where three perspectives collaborate to explore and define features:

### 1. Business Perspective (Product Owner/BA)

- What problem are we solving?
- What value does it provide?
- What are the business rules?

### 2. Development Perspective (Developer)

- How might we build this?
- What are the technical constraints?
- What are the edge cases?

### 3. Testing Perspective (Tester/QA)

- What could go wrong?
- What are we missing?
- How will we verify this works?

### Example Three Amigos Session

**Feature**: Password Reset

**Business**: "Users who forget their password need a way to reset it via email."

**Developer**: "We'll need to generate secure tokens with expiration. How long should tokens be valid?"

**Tester**: "What happens if they request multiple reset emails? Can old tokens still be used?"

**Business**: "Tokens should be valid for 1 hour. Multiple requests should invalidate old tokens."

**Developer**: "Should we rate-limit reset requests to prevent abuse?"

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