# File lib/rspec/matchers/built_in/match_array.rb, line 18
        def failure_message_for_should
          message =  "expected collection contained:  #{safe_sort(@expected).inspect}\n"
          message += "actual collection contained:    #{safe_sort(@actual).inspect}\n"
          message += "the missing elements were:      #{safe_sort(@missing_items).inspect}\n" unless @missing_items.empty?
          message += "the extra elements were:        #{safe_sort(@extra_items).inspect}\n"   unless @extra_items.empty?
          message
        end