name: ruby
description: Ruby development guidelines covering idiomatic code style, Ruby 3.x features, testing with RSpec, and best practices for building maintainable Ruby applications.

Ruby Development

You are an expert in Ruby development, including Ruby 3.x features, testing frameworks, and modern Ruby best practices.

Code Style and Structure

• Write concise, idiomatic Ruby code with accurate examples
• Adhere to Ruby community conventions and style guides
• Use snake_case for files, methods, and variables
• Use CamelCase for classes and modules
• Favor descriptive names like user_signed_in? and calculate_total

Ruby Language Features

• Leverage Ruby 3.x capabilities including:
• Pattern matching with case/in
• Endless methods for simple one-liners
• Keyword arguments for clarity
• Safe navigation operator (&.)
• Use blocks, procs, and lambdas effectively
• Apply metaprogramming judiciously

Syntax and Formatting

• Follow the Ruby Style Guide
• Employ expressive syntax features
• Prefer single quotes except when string interpolation is needed
• Use meaningful method and variable names
• Keep methods small and focused (Single Responsibility Principle)

Error Handling

• Apply exceptions for genuine edge cases only
• Implement proper logging with user-friendly messages
• Use custom exception classes for domain-specific errors
• Handle errors gracefully with appropriate rescue blocks

Object-Oriented Design

• Follow SOLID principles
• Favor composition over inheritance
• Use modules for shared behavior (mixins)
• Keep classes focused and cohesive

Testing Best Practices

RSpec Guidelines

• Write comprehensive coverage of typical cases, edge cases, and error conditions
• Use clear, descriptive naming conventions for test blocks
• Organize logically with describe for classes/methods and context for scenarios
• Use let and factories (FactoryBot) instead of fixtures
• Ensure test independence with minimal shared state
• Mock external services strategically while testing real behavior when possible

Test Structure

describe ClassName do
  describe '#method_name' do
    context 'when condition exists' do
      it 'does expected behavior' do
        expect(result).to eq(expected)
      end
    end
  end
end

Performance Optimization

• Profile code before optimizing
• Use appropriate data structures
• Leverage lazy enumerators for large collections
• Cache expensive computations

Security

• Sanitize user input
• Use parameterized queries
• Keep dependencies updated
• Follow security best practices for handling sensitive data