array_if.rb

# Source: http://gist.github.com/281687#file_array_if.rb
class Array
  def if(predicate)
    predicate ? self.first : self.last
  end
end

if __FILE__ == $0
  require 'test/unit'
  class ArrayTest < Test::Unit::TestCase
    def test_should_return_expensive
      price = 100
      assert_equal "expensive", ["expensive","cheap"].if(price > 50)
    end

    def test_should_return_cheap
      price = 25
      assert_equal "cheap", ["expensive","cheap"].if(price > 50)
    end
  end
end