# File test_format.rb, line 147
  def compareOutput (infile, perl, tail)
    perl_output = getPerlToCompare(perl)
    tail.each {|i| perl_output.push(i.chomp())} if (tail)
    File.open("#{infile}"){|file|
      lines = file.readlines
      lines.each_index {|i|
        line = lines[i].chomp!()
        if (!(line === (perl_output[i])))
          perl_name = "perl".ljust(infile.length)
          raise "testing error between \n" +
            "#{infile}>#{line}<\n#{perl_name}>#{perl_output[i]}<" 
        end
      }
      if (lines.size != perl_output.size)
        raise "testing error between #{infile} #{lines.size()} and " + 
          "#{perl} #{perl_output.size()}, not the same size" 
      else
        puts "keeping #{infile}" if @@keep
        File.delete(infile) unless (@@keep)
      end
    }
    true
  end