ruby - ルビ文字列比較

Question

rps_game_winnerCodeAcademy Labs でメソッド (以下を参照)を使用しようとすると、次の入力で問題なく動作します。

> rps_game_winner([ ["Dave", "P"], ["Armando", "S"] ])
valid value: p
valid value: s
=> ["Armando", "S"]

> rps_game_winner([ ["Allen", "P"], ["Richard", "P"] ])[0]
valid value: p
valid value: p
=> "Allen"

オートグレーダーの宿題に提出すると、常にNoSuchStrategyError.

Failure/Error: rps_game_winner([ ["Dave", "P"], ["Armando", "S"] ])[0].should eq("Armando"), "Incorrect Winner returned"
     NoSuchStrategyError:
       NoSuchStrategyError

誰か助けてくれませんか？ありがとう。

def rps_game_winner(game)
  raise WrongNumberOfPlayersError unless game.length == 2
  a1=[(game[0][1]).downcase]
  a2=[(game[1][1]).downcase]
  a3=a1.to_s
  a4=a2.to_s
  valid=["r","p","s"]

  if(valid.include?(a3))
    puts "valid value: "+a3
  else
    raise NoSuchStrategyError
  end

  if(valid.include?(a4))
    puts "valid value: "+a4
  else
    raise NoSuchStrategyError
  end

  if(win(a1, a2))
    return game[0]
  else
    if a1.eql?(a2)
      return game[0]
    else
      return game[1]
    end
  end

  return game[0] if a1.eql?(a2)
end