# File lib/action_controller/assertions/selector_assertions.rb, line 552
      def assert_select_email(&block)
        deliveries = ActionMailer::Base.deliveries
        assert !deliveries.empty?, "No e-mail in delivery list"

        for delivery in deliveries
          for part in delivery.parts
            if part["Content-Type"].to_s =~ /^text\/html\W/
              root = HTML::Document.new(part.body).root
              assert_select root, ":root", &block
            end
          end
        end
      end