i=0; i < childCount; i++) {
    var s = document.createElement('span');
    s.textContent = i;
    fragment.appendChild(s);
  }
  var l = document.createElement('span');
  l.textContent = 'last';
  rere.root.appendChild(l);
  rere.root.insertBefore(fragment, l);
  var added = rere.root.querySelectorAll('span');
  assert.equal(added.length, childCount+1);
  assert.equal(added[added.length-1], l);
  for (i=0; i < added.length; i++) {
    rere.root.removeChild(added[i]);
  }
  assert.equal(rere.root.querySelec