ip_range_iana.rb

require 'ipaddr'
require 'test/unit'

class TC_MyTest < Test::Unit::TestCase
  REGEX_UNDER_QUESTION = %r{172\.(?:[1][6-9]|[2][0-9]|[3][0-1])\.\d+\.\d+}

  def setup
    start = IPAddr.new('172.16.0.0')
    finish = IPAddr.new('172.31.255.255')
    @ip_range = (start..finish).map(&:to_s)
  end

  def test_green
    assert_block 'Range is not covered' do
     @ip_range.select{|x| !x[REGEX_UNDER_QUESTION]}.empty?
    end
  end

  def test_red
    assert_block 'Poke teh range!' do
      @ip_range += %w{ 172.12.1.2 172.32.1.1 168.12.21.1 }
      @ip_range.select{|x| !x[REGEX_UNDER_QUESTION]}.size.eql?(3)
    end
  end
end