test_visibility.rb

# Testing Ruby's method visibility with Modules

module A
  def public_method
    puts :public_method
  end

  protected
  def protected_method
    puts :protected_method
  end

  private
  def private_method
    puts :private_method
  end
end

class B
  include A

  def testing_visibility
    public_method
    protected_method
    private_method
  end
end

b = B.new
b.testing_visibility
b.public_method
b.protected_method
b.private_method

# ruby test_visibility.rb