
    </div>
    <script>
      const l1 = document.getElementById('l1');
      test(l1.childElementCount === 1, 'div#l1 has one child');

      data.l1 = ['a'];
      test(l1.childElementCount === 2, 'div#l1 has two children');
      test(l1.children[0]?.innerText === 'a', 'div#l1 child 0 is a');
      test(
        l1.children[0]?.tagName.toLowerCase() === 'red-p',
        'div#l1 child elem is red-p'
      );

      data.l1.push('b');
      test(l1.childElementCount === 3, 'div#l1 has three children');
  