prioritize-rendering-after-input-click.html

<!doctype html>
<title>Blink Scheduler Prioritize Rendering After Input - Click</title>
<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/utils.js"></script>

<h1>Test Page</h1>
<button id=button>Click me!</button>

<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;
      };

      const button = document.getElementById('button');

      const inputHandler = (e) => {
        if (eventCount >= MAX_EVENTS) {
          return;
        }
        ++eventCount;
        requestAnimationFrame(inputFrameCallback);
        if (e.type == 'pointerup') {
          test_driver.click(button);
        }
        // Spin long enough to increase the probability the next click is scheduled
        // before the next task.
        spin(50);
      };

      button.addEventListener('pointerdown', inputHandler);
      button.addEventListener('pointerup', inputHandler);

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

      test_driver.click(button);
    });

    // This should typically be 2: the pointerdown event and the pointerup, the
    // latter of which likely runs at the start of the subsequent BeginMainFrame.
    // Without the prioritize rendering after input policy, this will likely be
    // 20, depending on timing.
    assert_less_than_equal(eventCountDuringRafAfterInput, 5);
  }, 'Test that pointer input does not starve rendering');
};

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