prioritize-rendering-after-input-keyboard.html

<!doctype html>
<title>Blink Scheduler Prioritize Rendering After Input - Keyboard</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/utils.js"></script>

<h1>Test Page</h1>
<textarea id="text" autofocus></textarea>

<script>
'use strict';

window.onload = () => {
  promise_test(async t => {
    const eventCountDuringRafAfterInput = await new Promise(async resolve => {
      const MAX_EVENTS = 20;
      let eventCount = 0;

      const inputFrameCallback = () => {
        resolve(eventCount);
        // Prevent any more input events from running.
        eventCount = MAX_EVENTS;
      }

      document.getElementById('text').addEventListener('keypress', () => {
        if (eventCount >= MAX_EVENTS) {
          return;
        }
        ++eventCount;
        requestAnimationFrame(inputFrameCallback);
        window.eventSender.keyDownAsync('A');
        spin(30);
      });

      await requestAnimationFramePromise();
      await scheduler.yield();

      window.eventSender.keyDownAsync('A');
    });

    // This should typically be 3: the first input event, the one scheduled early
    // in the event handler (which races frame being scheduled), and the one
    // scheduled from the second input, which will run at the start of the
    // BeginMainFrame. Without the prioritize rendering after input policy, this
    // will be 20, so this suffices as a regression test.
    assert_less_than_equal(eventCountDuringRafAfterInput, 5);
  }, 'Test that keyboard input does not starve rendering');
};

</script>
chromium/third_party/blink/web_tests/wpt_internal/scheduler/integration_tests/prioritize-rendering-after-input-keyboard.html
