ng.expectEqual(true, link.appendChild(next, cdata) !== undefined);
  testing.expectEqual(true, cdata.nextElementSibling.localName === 'a');

  testing.expectEqual(true, cdata.previousElementSibling === null);

  // create a prev element
  let prev = document.createElement('div');
  testing.expectEqual(true, link.insertBefore(prev, cdata) !== undefined);
  testing.expectEqual('div', cdata.previousElementSibling.localName);

  cdata.appendData(' modified');
  testing.expectEqual('OK modified', cdata.data);

 