
    <script>
      suite('ParentNode append', function () {
        suite('Document', function () {
          test('Appends an element', () => {
            const doc = document.implementation.createHTMLDocument('');
            while (doc.firstChild) {
              doc.removeChild(doc.firstChild);
            }

            const child = document.createElement('html');
            doc.append(child);

            assert(doc.childNodes.length === 1);
            assert(doc.childNodes[0] === child);
       