# File lib/test/unit/assertions.rb, line 2109
        def to_s
          message_parts = []
          if (@head)
            head = @head
            head = head.call if head.respond_to?(:call)
            head = head.to_s
            unless(head.empty?)
              message_parts << add_period(head)
            end
          end
          tail = template.result(@parameters.collect{|e| convert(e)})
          message_parts << tail unless(tail.empty?)
          message_parts.join("\n")
        end