Test how Ruby inheritance works and Modules

ruby_inheritance.rb

module ModuleToBeIncludedByParentClass
  def parent; puts 'from included module by parent'; super if defined?(super); end
end
module ModuleToBeExtendedByParentClass
  def parent; puts 'from extended module by parent'; super if defined?(super); end
end

module ModuleToBeIncludedByChildClass
  def child; puts 'from included module by child'; super if defined?(super); end
end
module ModuleToBeExtendedByChildClass
  def child; puts 'from extended module by child'; super if defined?(super); end
end

class ParentClass
  include ModuleToBeIncludedByParentClass
  extend ModuleToBeExtendedByParentClass

  def self.parent; puts 'from parent class self.parent method'; super if defined?(super); end
  def self.child; puts 'from parent class self.child method'; super if defined?(super); end
  def parent; puts 'from parent class parent method'; super if defined?(super); end
  def child; puts 'from parent class child method'; super if defined?(super); end
end

class ChildClass < ParentClass
  include ModuleToBeIncludedByChildClass
  extend ModuleToBeExtendedByChildClass

  def self.parent; puts 'from child class self.parent method'; super if defined?(super); end
  def self.child; puts 'from child class self.child method'; super if defined?(super); end
  def parent; puts 'from child class parent method'; super if defined?(super); end
  def child; puts 'from child class child method'; super if defined?(super); end
end

puts '### class methods'
ParentClass.parent
puts ''
ChildClass.parent
puts ''
ChildClass.child
puts ''
puts '### instance methods'
ParentClass.new.parent
puts ''
ChildClass.new.parent
puts ''
ChildClass.new.child

#=> ### class methods
#=> from parent class self.parent method
#=> from extended module by parent
#=> 
#=> from child class self.parent method
#=> from parent class self.parent method
#=> from extended module by parent
#=> 
#=> from child class self.child method
#=> from extended module by child
#=> from parent class self.child method
#=> 
#=> ### instance methods
#=> from parent class parent method
#=> from included module by parent
#=> 
#=> from child class parent method
#=> from parent class parent method
#=> from included module by parent
#=> 
#=> from child class child method
#=> from included module by child
#=> from parent class child method