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_gem_command.rb
    path of file: ./repos/ruby-packer/ruby/test/rubygems
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
require 'rubygems/test_case'
require 'rubygems/command'

class Gem::Command

  public :parser

end

class TestGemCommand < Gem::TestCase

  def setup
    super

    @xopt = nil

    @common_options = Gem::Command.co
    
  def test_self_add_specific_extra_args
    added_args = %w[--all]
    @cmd.add_option('--all') { |v,o| }

    Gem::Command.add_specific_extra_args @cmd_name, added_args

    assert_equal added_args, Gem::Command.specific_extra_args(@cmd_name)

    h = @cmd.add_extra_args []

    assert_equal added_args, h
  end