<!DOCTYPE html>
<html>
<meta charset=utf-8 />
<title>Event Timing: PerformanceObserver sees entries with buffered flag</title>
<button id='button'>Generate a 'click' event</button>
<script src=/resources/testharness.js></script>
<script src=/resources/testharnessreport.js></script>
<script src=/resources/testdriver.js></script>
<script src=/resources/testdriver-vendor.js></script>
<script src=resources/event-timing-test-utils.js></script>
<script>
  let firstInputSeen = false;
  let eventSeen = false;
  async_test(t => {
    assert_implements(window.PerformanceEventTiming, 'Event Timing is not supported.');
    const validateEntry = t.step_func(entry => {
      if (entry.entryType === 'first-input')
        firstInputSeen = true;
      else if (entry.entryType === 'event')
        eventSeen = true;
      else
        assert_unreached('Should only observe Event Timing entries!');
    });
    // First observer creates second in callback to ensure the entry has been dispatched by the time
    // the second observer begins observing.
    new PerformanceObserver((list, obs) => {
      list.getEntries().forEach(validateEntry);
      if (!firstInputSeen || !eventSeen)
        return;

      obs.disconnect();
      firstInputSeen = false;
      eventSeen = false;
      // Second observer requires 'buffered: true' to see entries.
      const bufferedObserver = new PerformanceObserver(entryList => {
          entryList.getEntries().forEach(validateEntry);
          if (firstInputSeen && eventSeen)
            t.done();
      });
      bufferedObserver.observe({type: "event", buffered: true});
      bufferedObserver.observe({type: 'first-input', buffered: true});
    }).observe({entryTypes: ['event', 'first-input']});
    clickAndBlockMain('button');
  }, "PerformanceObserver with buffered flag sees previous Event Timing entries");
</script>
</html>