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: window_test.rb
    path of file: ./repos/ae_page_objects/test/unit/single_window
    
    the code of the file until where you have to start completion: require 'unit_helper'

require 'ae_page_objects/single_window/window'

module AePageObjects
  module SingleWindow
    class WindowTest < AePageObjectsTestCase

      def test_initialize
        window 
    
      def test_current_document=
        window = Window.new

        assert_nil window.current_document

        document_mock = mock(:stale! => true)
        window.current_document = document_mock

        assert_equal document_mock, window.current_document

        window.current_document = "whatever"
        assert_equal "whatever", window.current_document
      end
    end
  end