# File lib/test/unit/diff.rb, line 725
      def diff(differ_class, from, to, options={})
        differ = differ_class.new(from.split(/\r?\n/), to.split(/\r?\n/))
        lines = differ.diff(options)
        if Object.const_defined?(:EncodingError)
          begin
            lines.join("\n")
          rescue EncodingError
            lines.collect {|line| line.force_encoding("ASCII-8BIT")}.join("\n")
          end
        else
          lines.join("\n")
        end
      end