iv instanceof HTMLDivElement, 'el#du1 has shadowRoot div');

      const du1h1 = du1div.children[0];
      test(du1h1 instanceof HTMLHeadingElement, 'el#du1 has a h# element');

      const du1p = du1div.children[1];
      test(du1p instanceof HTMLParagraphElement, 'el#du1 has a p element');
      test(
        document.querySelector('[sb-mark="user.name"]') instanceof
          HTMLSpanElement,
        'user.name el is a span'
      );
      test(
        document.querySelector('[sb-mark="user.age"]') inst