Paperclip factory_girl macro working with Rails 3.1rc4

factories.rb

Factory.define :application do |factory|
  factory.attachment(:sample, "public/samples/sample.doc", "application/msword")
end

factory_attachment.rb

require 'action_dispatch/testing/test_process'

Factory.class_eval do
  def attachment(name, path, content_type = nil)
    path_with_rails_root = Rails.root.join(path)
    uploaded_file = if content_type
                      Rack::Test::UploadedFile.new(path_with_rails_root, content_type)
                    else
                      Rack::Test::UploadedFile.new(path_with_rails_root)
                    end

    add_attribute name, uploaded_file
  end
end

It is working for me. But you don't need it anymore. There is factory in Factory girl already.
Example is in comment - https://github.com/thoughtbot/paperclip/blob/master/shoulda_macros/paperclip.rb#L84

Thanks. I hadn't seen that.