You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: test_io_m17n.rb
    path of file: ./repos/jruby/test/mri/ruby
    
    the code of the file until where you have to start completion: # coding: US-ASCII
# frozen_string_literal: false
require 'test/unit'
require 'tmpdir'
require 'tempfile'
require 'timeout'

class TestIO_M17N < Test::Unit::TestCase
    
  def test_open_w_enc_in_opt2
    with_tmpdir {
      open("tmp", "w", external_encoding: "euc-jp") {|f|
        assert_equal(Encoding::EUC_JP, f.external_encoding)
        assert_equal(nil, f.internal_encoding)
      }
    }
  end