eElement('fieldset'));
  fieldset.setAttribute("checkable", "single");
  const single1 = fieldset.appendChild(document.createElement('menuitem'));
  const single2 = fieldset.appendChild(document.createElement('menuitem'));

  single1.checked = true;
  single2.checked = true;

  assert_false(single1.checked, "single1 is unchecked");
  assert_true(single2.checked, "single2 is checked");
}, "checkable menuitem exclusivity when disconnected");

test(() => {
  const menulist = document.createElement('menulist');