ruby delegate DelegateClass removing global scope

delegate_class.rb

require 'delegate'
def test_that?(n)
  return n < 12
end

class MyID < DelegateClass(Integer)
  def initialize(num)
    @small = false
    if  test_that?(num)
        @small = true
    end
    super(num)
  end
  def small?
      @small
  end
end

puts "small" if test_that?(4)
id = MyID.new(11)