factory_girl association recursion

gistfile1.rb

# Question model - question.rb
class Question < ActiveRecord::Base
  attr_accessible :text, :survey_id

  belongs_to :survey

  validates_presence_of :text, :survey
end

#Survey model - survey.rb
class Survey < ActiveRecord::Base
  attr_accessible :name

  has_many :questions, :dependent => :destroy

  validates :name, :presence => true
end


#factories.rb
  factory :question do
    text "Who doesn't love the rubies?"
    association :survey, :factory => :survey
  end
  
  factory :survey do
    name 'Survey 1'
    after_build do |s|
      2.times { s.questions.build(FactoryGirl.attributes_for(:question)) }
    end
  end
end

# Model tests - question_spec.rb
  it "should require a non-blank text" do
    FactoryGirl.build(:question, :text => "      ").should_not be_valid
  end

#rspec error:
Question validation should require a non-blank text
     Failure/Error: FactoryGirl.build(:question, :text => "      ").should_not be_valid
     ActiveRecord::RecordInvalid:
       Validation failed: Questions survey can't be blank