# File lib/rspec/matchers/built_in/match_array.rb, line 12
        def failure_message_for_should
          if actual.respond_to? :to_ary
            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?
          else
            message = "expected an array, actual collection was #{actual.inspect}"
          end

          message
        end