longtask-timing/spin-eventloop-not-longtask.html

<!DOCTYPE HTML>
<meta charset=utf-8>
<title>LongTask Timing: synchronous XHR</title>
<body>

<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/utils.js"></script>
<link rel="stylesheet" href="/resource-timing/resources/delay-css.py?delay=1000" />
<h1>Long Task: Spin event loop</h1>
<div id="log"></div>
<script>
setup(() => assert_implements(window.PerformanceLongTaskTiming, 'Longtasks are not supported.'));

promise_test(async t => {
    const didReceiveLongTask = false;
    new PerformanceObserver(() => {
        didReceiveLongTask = true;
    }).observe({entryTypes: ['longtask']});

    await new Promise(resolve => window.addEventListener('load', resolve));
    assert_false(didReceiveLongTask);
}, 'Waiting for load event (spinning an event loop), is not a longtask');
</script>
</body>