lib/fixture_builder/builder.rb
def fixtures_class
      if defined?(ActiveRecord::FixtureSet)
        ActiveRecord::FixtureSet
      elsif defined?(ActiveRecord::Fixtures)
        ActiveRecord::Fixtures
      else
        ::Fixtures
      end
    end
def fixtures_class
      if defined?(ActiveRecord::FixtureSet)
        ActiveRecord::FixtureSet
      elsif defined?(ActiveRecord::Fixtures)
        ActiveRecord::Fixtures
      else
        ::Fixtures
      end
    end
Rails 3.0 and 3.1+ support