RSpec 2 speccing a static ActiveRecord method

I've got a pretty basic static method on an ActiveRecord model:

#./app/models/comic.rb
class Comic < ActiveRecord::Base
  class << self
    def furthest
      Comic.maximum(:comic_id) || 0
    end
  end
end

When executing Comic.furthest in the Rails console it returns 0 as I expect. The problem is I am trying to spec this behavior for both the presence and absence of records:

#./spec/app/models/comic_spec.rb
require 'spec_helper'

describe Comic do
  describe "#furthest" do
    subject { Comic.furthest }

    context "when there are no rows in the database" do
      it { should == 0 }
    end

    context "when there are rows in the database" do
      before do
        Factory.create(:comic, :comic_id => 100)
        Factory.create(:comic, :comic_id => 99)
      end

      it { should == 100 }
    end
  end
end

All of this appears very basic and straightforward, however my specs are failing with the message:

1) Comic#furthest when there are no rows in the database 
 Failu开发者_运维问答re/Error: it { should == 0 }
   expected: 0
        got: nil (using ==)
 # ./spec/models/comic_spec.rb:8:in `block (4 levels) in <top (required)>'

Even if I change furthest to simply:

def furthest
  0
end

I still get nil (using ==).

The second spec, it { should == 100 } passes with the original Comic.maximum(:comic_id) || 0 definition, as if the Factory.create invocations are required for #furthest to not return nil.

What am I doing wrong?

---

I am fairly confident this was a problem with me using the p180 release of Ruby 1.9.2 with custom patches to improve require performance. After upgrading to p290 this problem is gone.