# File test_format.rb, line 539
  def helper_test_twelve (body_fmt, file_name)
    var_one, var_two, var_three, var_four = 1, 2, 3, 4.3
    File.open(file_name, 
              File::CREAT | File::WRONLY | File::TRUNC) { |file|
      body_fmt.io = file
      body_fmt.printFormat(binding) 
    }
    output = []
    File.open( file_name ){ |file|
      output = file.readlines()
    }
    
    reader = FormatReader.new(body_fmt)
    res = reader.readFormat(output)
    
    #since we're keying on just @ we can't tell class without the binding
    assert(res['var_one'] == var_one.to_s)
    assert(res['var_two'] == var_two.to_s)
    assert(res['var_three'] == var_three.to_s)
    assert(res['var_four'] == var_four)
    # we need to compare last since compare may delete the file when its done
    assert(compareOutput(file_name, 
                         "./format_test.pl 12", nil))
  end