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_ruby_lex.rb
    path of file: ./repos/ruby-packer/ruby/test/irb
    
    the code of the file until where you have to start completion: $LOAD_PATH.unshift File.expand_path('../../lib', __FILE__)
require 'irb/ruby-lex'
require 'test/unit'
require 'ostruct'

module TestIRB
  class TestRubyLex < Test::Unit::TestCase
    Row = Struct.new(:content, :current_line_spaces, :new_line_spaces)

    class MockIO
      def initialize(params, &assertion)
        @params = params
        @assertion = assertion
      end

      def auto_indent(&block)
        result = block.call(*@params)
        @assertion.call(result)

    
    def assert_indenting(lines, correct_space_count, add_new_line)
      lines = lines + [""] if add_new_line
      last_line_index = lines.length - 1
      byte_pointer = lines.last.length

      ruby_lex = RubyLex.new()
      io = MockIO.new([lines, last_line_index, byte_pointer, add_new_line]) do |auto_indent|
        error_message = "Calculated the wrong number of spaces for:\n #{lines.join("\n")}"
        assert_equal(correct_space_count, auto_indent, error_message)
      end
      ruby_lex.set_input(io)
      context = OpenStruct.new(auto_indent_mode: true)
      ruby_lex.set_auto_indent(context)
    end