diff (lib/unit_diff.rb)

    # File lib/unit_diff.rb, line 218
      def diff expect, butwas
        output = nil

        Tempfile.open("expect") do |a|
          a.write(massage(expect))
          a.rewind
          Tempfile.open("butwas") do |b|
            b.write(massage(butwas))
            b.rewind

            diff_flags = $u ? "-u" : $c ? "-c" : ""
            diff_flags += " -b" if $b

            result = `#{DIFF} #{diff_flags} #{a.path} #{b.path}`
            output = if result.empty? then
                       "[no difference--suspect ==]"
                     else
                       result.split(/\n/)
                     end

            if $k then
              warn "moving #{a.path} to #{a.path}.keep"
              File.rename a.path, a.path + ".keep"
              warn "moving #{b.path} to #{b.path}.keep"
              File.rename b.path, b.path + ".keep"
            end
          end
        end

        output
      end