# File lib/action_controller/assertions.rb, line 311
      def clean_backtrace(&block)
        begin
          yield
        rescue AssertionFailedError => e         
          path = File.expand_path(__FILE__)
          raise AssertionFailedError, e.message, e.backtrace.reject { |line| File.expand_path(line) =~ /#{path}/ }
        end           
      end