layout-instability/pointermove-becomes-drag.html

<!DOCTYPE html>
<title>Layout Instability: no shift in pointerdown becoming dragging</title>
<link rel="help" href="https://wicg.github.io/layout-instability/" />
<style>

body { margin: 0; }
#draggable {
  top:50px;
  left:50px;
  width:50px;
  height:50px;
  background-color:blue;
  position:absolute
}

</style>
<div id="draggable" ></div>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-actions.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<script src="resources/util.js"></script>
<script>

const draggable = document.getElementById("draggable");
draggable.addEventListener('touchmove', function(event) {
  let touch = event.targetTouches[0];

  // Move the element when the finger moves.
  draggable.style.top = touch.pageY - 25 + 'px';
  event.preventDefault();
}, false);

generateTouchDragSequence = () => new test_driver.Actions()
    .addPointer("touch1", "touch")
    .pointerMove(0, 0, {origin: draggable})
    .pointerDown()
    .pointerMove(0, 15, {origin: draggable})
    .pause(100)
    .pointerMove(0, 30, {origin: draggable})
    .pause(100)
    .pointerMove(0, 45, {origin: draggable})
    .pause(100)
    .pointerUp()
    .pause(100);

promise_test(async(test) => {
  const watcher = new ScoreWatcher;
  let eventWatcher = new EventWatcher(test, draggable, ["pointerup"]);
  let donePromise = eventWatcher.wait_for(["pointerup"], { record: 'all' });

  // Wait for the initial render to complete.
  await waitForAnimationFrames(2);

  // Send pointer events for a touch drag.
  await generateTouchDragSequence().send();

  // wait for pointerUp before running the test
  await donePromise;

  // Touch moves which drag the objects should be counted as the excluding inputs
  // for the layout shift.
  assert_greater_than(watcher.score, 0);
  assert_equals(watcher.scoreWithInputExclusion, 0);

}, "No Shift in pointerdown reported when it becomes a touch drag.");

</script>