 checkable.checked = true;
  assert_equals(checkable.checked, true, "checkable menuitem is checked");
  assert_true(checkable.matches(":checked"));
}, "menuitem in menulist");

test(() => {
  assert_false(single1.checked, "single1 not checked");
  assert_false(single1.matches(":checked"), "single1 not :checked");
  assert_false(single2.checked, "single2 not checked");
  assert_false(single2.matches(":checked"), "single2 not :checked");
  assert_false(single3.checked, "single3 not checked");
  assert_false(s