class UnitDiff

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