I found it very helpful to write my own quick and dirty  
implementation of GOPS for testing bots.

def fight(ai1_class, ai2_class)
   ai1 = ai1_class.new
   ai2 = ai2_class.new
   deck = (1..13).sort_by{ rand }.to_a
   deck1 = (1..13).to_a
   deck2 = (1..13).to_a
   points1 = 0
   points2 = 0
   while card = deck.shift
     round = 13 - deck.size
     card1 = ai1.get_card(round, card, deck1, deck2)
     card2 = ai2.get_card(round, card, deck2, deck1)
     deck1.delete card1
     deck2.delete card2
     raise "#{ai1} play corrupt (last play: #{card1})" unless  
deck1.size == deck.size
     raise "#{ai2} play corrupt (last play: #{card2})" unless  
deck2.size == deck.size
     if card1 > card2
       points1 += card
     elsif card2 > card1
       points2 += card
     end
   end
   [points1, points2]
end

def best_of_100(ai1, ai2)
   win1 = 0
   win2 = 0
   100.times do
     result = fight(ai1, ai2)
     case result[0] <=> result[1]
     when 1
       win1 += 1
     when -1
       win2 += 1
     end
   end
   [win1, win2]
end


class SimpleAi
   def get_card(round, card, deck, opponent_deck)
	  card
   end
end