# File lib/test/unit/assertions.rb, line 1784
          def delayed_diff(from, to)
            delayed_literal do
              from, to = prepare_for_diff(from, to)

              diff = "" if from.nil? or to.nil?
              diff ||= Diff.readable(from, to)
              if /^[-+]/ !~ diff
                diff = ""
              elsif /^[ ?]/ =~ diff or /(?:.*\n){2,}/ =~ diff
                diff = "\n\ndiff:\n#{diff}"
              else
                diff = ""
              end

              if Diff.need_fold?(diff)
                folded_diff = Diff.folded_readable(from, to)
                diff += "\n\nfolded diff:\n#{folded_diff}"
              end

              diff
            end
          end