<!DOCTYPE html>
<title>
  Adding a new snap area while already snapped should not make the scroller snap to it.
</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: both mandatory;
}

#initial-target {
  width: 300px;
  height: 300px;
  top: 100px;
  left: 100px;
  background-color: green;
  scroll-snap-align: start;
}

#other-target {
  width: 300px;
  height: 300px;
  top: 300px;
  left: 300px;
  background-color: red;
  scroll-snap-align: start;
}

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

<div id="scroller">
  <div class="area"></div>
  <div id="initial-target"></div>
  <div id="other-target"></div>
</div>

<script>
const initial_target = document.getElementById("initial-target");
const other_target = document.getElementById("other-target");
const scroller = document.getElementById("scroller");

test(() => {
  scroller.removeChild(other_target);
  scroller.scrollTo(0,0);
  assert_equals(scroller.scrollTop, 100);
  assert_equals(scroller.scrollLeft, 100);

  scroller.appendChild(other_target);
  assert_equals(scroller.scrollTop, 100);
  assert_equals(scroller.scrollLeft, 100);
}, "Adding a new snap area while already snapped should not make the scroller snap to it.");
</script>