关联在测试中找不到创建的对象

我的应用程序中有以下模型:

class Game < ActiveRecord::Base
   has_many :players
   has_many :villages, :through => :players
end

class Village < ActiveRecord::Base
   belongs_to :player
end

class Player < ActiveRecord::Base
   belongs_to :game
   has_many :villages

   before_create :build_starting_village

   protected

   def build_starting_village
     villages.build(some_attributes)
   end
end

我正在用Shoulda/FactoryGirl测试部分游戏功能,以下是测试:

  setup do
    @villages = []
    5.times do |i|
      p = Factory(:player, :game => @game)
      v = p.villages.first
      assert v
      @villages << v
    end
    assert_equal @villages.size, @game.villages.size
  end

问题是最后一个断言失败了。我尝试过很多丑陋的事情,比如:

    @game.villages(true)
    @game.players(true)
    @game = Game.find(@game.id)

但我看不到问题的根源。我尝试过禁用事务性fixture(我不使用fixture,但我认为这也会影响到factorygirl),它在其他测试中有所帮助,但在这里没有效果。