<!DOCTYPE html>
<title>
  Updating the scroll-snap-type of a snap container should make it resnap accordingly.
</title>
<link rel="help" href="https://drafts.csswg.org/css-scroll-snap/#re-snap" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
div {
  position: absolute;
  margin: 0;
}

#scroller {
  height: 500px;
  width: 500px;
  overflow: hidden;
  scroll-snap-type: none;
}

#y-target {
  width: 300px;
  height: 300px;
  top: 100px;
  left: 0;
  background-color: green;
  scroll-snap-align: start none;
}

#x-target {
  width: 300px;
  height: 300px;
  top: 0;
  left: 100px;
  background-color: red;
  scroll-snap-align: none start;
}

.area {
  width: 2000px;
  height: 2000px;
}
</style>

<div id="scroller">
  <div class="area"></div>
  <div id="x-target"></div>
  <div id="y-target"></div>
</div>

<script>
const x_target = document.getElementById("x_target");
const y_target = document.getElementById("y_target");
const scroller = document.getElementById("scroller");

function cleanup() {
  scroller.style.setProperty("scroll-snap-type", "none");
}

test(t => {
  t.add_cleanup(cleanup);
  scroller.scrollTo(0,0);
  assert_equals(scroller.scrollTop, 0);
  assert_equals(scroller.scrollLeft, 0);

  scroller.style.setProperty("scroll-snap-type", "y mandatory");
  assert_equals(scroller.scrollTop, 100);
  assert_equals(scroller.scrollLeft, 0);
}, "Changing the scroller's snap type to y should make it resnap on the y-axis.");

test(t => {
  t.add_cleanup(cleanup);
  scroller.scrollTo(0,0);
  assert_equals(scroller.scrollTop, 0);
  assert_equals(scroller.scrollLeft, 0);

  scroller.style.setProperty("scroll-snap-type", "x mandatory");
  assert_equals(scroller.scrollLeft, 100);
  assert_equals(scroller.scrollTop, 0);
}, "Changing the scroller's snap type to x should make it resnap on the x-axis.");


test(t => {
  t.add_cleanup(cleanup);
  scroller.scrollTo(0,0);
  assert_equals(scroller.scrollTop, 0);
  assert_equals(scroller.scrollLeft, 0);

  scroller.style.setProperty("scroll-snap-type", "x mandatory");
  assert_equals(scroller.scrollLeft, 100);
  assert_equals(scroller.scrollTop, 0);

  scroller.style.setProperty("scroll-snap-type", "y mandatory");
  assert_equals(scroller.scrollTop, 100);
}, "Changing the scroller's snap type axis should make it resnap.");
</script>
