<!DOCTYPE html>
<link rel=author href="mailto:jarhar@chromium.org">
<link rel=help href="https://github.com/whatwg/html/pull/9142">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<dialog>hello</dialog>

<script>
test(() => {
  const dialog = document.querySelector('dialog');

  // calling close() on a dialog that is already closed should not throw.
  dialog.close();

  dialog.show();
  // calling show() on a dialog that is already showing non-modal should not throw.
  dialog.show();
  assert_throws_dom('InvalidStateError', () => dialog.showModal(),
    'Calling showModal() on a dialog that is already showing non-modal should throw.');
  dialog.close();

  dialog.showModal();
  assert_throws_dom('InvalidStateError', () => dialog.show(),
    'Calling show() on a dialog that is already showing modal should throw.');
  // calling showModal() on a dialog that is already showing modal should not throw.
  dialog.showModal();
});
</script>
