failure_message_for_should

# File lib/spec/matchers/match_array.rb, line 17
      def failure_message_for_should
        message =  "expected collection contained:  #{@expected.sort.inspect}\n"
        message += "actual collection contained:    #{@actual.sort.inspect}\n"
        message += "the missing elements were:      #{@missing_items.sort.inspect}\n" unless @missing_items.empty?
        message += "the extra elements were:        #{@extra_items.sort.inspect}\n" unless @extra_items.empty?
        message
      end