chromium/third_party/blink/web_tests/external/wpt/notifications/tag.https.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>Notification.tag (two tags with same or different value)</title>
<link rel="author" title="Intel" href="http://www.intel.com/">
<link rel="author" title="Xin Liu" href="mailto:[email protected]">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/helpers.js"></script>
<script>
function promiseEvent(target, eventName, syncListener) {
    return new Promise(resolve => {
        target.addEventListener(eventName, ev => {
            syncListener?.();
            resolve(ev);
        }, { once: true });
    });
}

promise_setup(async () => {
  await trySettingPermission("granted");
});

promise_test(async t => {
    const tom1 = new Notification("New Email to tom", {
        tag: "Tom"
    });
    t.add_cleanup(() => tom1.close());

    let closed = false;
    const promiseCloseEvent = promiseEvent(tom1, "close", () => closed = true);
    await promiseEvent(tom1, "show");

    const rose = new Notification("New Email to Rose", {
        tag: "Rose"
    });
    t.add_cleanup(() => rose.close());
    await promiseEvent(rose, "show");
    assert_false(closed, "Different tag should not close the first notification");

    const tom2 = new Notification("New Email to tom", {
        tag: "Tom"
    });
    t.add_cleanup(() => tom2.close());

    await promiseCloseEvent; // This should not timeout
}, "Opening two notifications with the same tag should close the first one");
</script>