title: FactoryGirl sequence not incrementing
body: <p>I'm using FactoryGirl to create instances of a date dimension model for a Rails-related gem. My factory looks like this:</p>
  
  <pre><code>FactoryGirl.define do
    sequence :next_day do |n|
      Date.new(2000,12,31) + n.days
    end
  
    factory :date_dimension do
      the_date = FactoryGirl.generate(:next_day)
      date {the_date.to_s}
      calendar_year {the_date.strftime("%Y")}
      (...other attributes created similarly to calendar_year)
    end
  
  end
  </code></pre>
  
  <p>Out of frustration I actually built a little test to show what's not working:</p>
  
  <pre><code>describe "working date factories" do
    before(:all) do
      @date_dimension = FactoryGirl.create(:date_dimension)
      @jan_two = FactoryGirl.create(:date_dimension)
    end
  
    describe "sequence incrementing" do
      it "returns a date dimension object ok" do
        @date_dimension.date.should == "2001-01-01"
      end
      it "returns the next date in the sequence" do
        @jan_two.date.should == "2001-01-02"
      end
    end
  end
  </code></pre>
  
  <p>When I run that test, I get:</p>
  
  <pre><code>working date factories
    sequence incrementing
      returns a date dimension object ok
      returns the next date in the sequence (FAILED - 1)
  
  Failures:
  
    1) working date factories sequence incrementing returns the next date in the sequence
       Failure/Error: @jan_two.date.should == "2001-01-02"
         expected: "2001-01-02"
              got: "2001-01-01" (using ==)
  </code></pre>
  
  <p>I've read a bunch of other questions related to sequences, but it doesn't seem that I'm making the mistakes identified therein. It's a different (likely dumber) mistake. What is it?</p>