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_case_mapping.rb
    path of file: ./repos/ruby-packer/ruby/test/ruby/enc
    
    the code of the file until where you have to start completion: # Copyright © 2016 Kimihito Matsui (松井 仁人) and Martin J. Dürst (duerst@it.aoyama.ac.jp)

require "test/unit"

# preliminary tests, using  as a guard
# to test new implementation strategy
class TestCaseMappi
    
  def check_capitalize_properties(expected, start, *flags)
    assert_equal expected, start.capitalize(*flags)
    temp = start.dup
    assert_equal expected, temp.capitalize!(*flags) unless expected==temp
    assert_equal nil, temp.capitalize!(*flags) if expected==temp
    assert_equal expected, expected.capitalize(*flags)
    temp = expected.dup
    assert_nil   temp.capitalize!(*flags)
  end