<!DOCTYPE html>
<link rel="help" href="https://drafts.csswg.org/css-scroll-snap-1/#scroll-snap-type" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
div {
  position: absolute;
}
#scroller {
  overflow: hidden; /* TODO: Use scrollbar-width: none */
  scroll-snap-type: x mandatory;
  width: 500px;
  height: 500px;
}
.space {
  width: 2000px;
  height: 2000px;
}
#target {
  height: 200px;
  width: 200px;
  left: 50px;
  background-color: blue;
}
</style>
<div id="scroller">
  <div class="space"></div>
  <div id="target"></div>
</div>
<script>
test(() => {
  target.style.scrollSnapAlign = "start";
  target.style.transform = "translateX(300px)";
  scroller.scrollTo(10, 0);
  assert_equals(scroller.scrollLeft, 350 /* left + translateX(300px) */);
  assert_equals(scroller.scrollTop, 0);
}, "Snaps to the transformed snap start position");

test(() => {
  target.style.scrollSnapAlign = "end";
  target.style.transform = "translateX(300px)";
  scroller.scrollTo(10, 0);
  assert_equals(scroller.scrollLeft,
                50 /* left + width + translateX(300px) - scroller.width */);
  assert_equals(scroller.scrollTop, 0);
}, "Snaps to the transformed snap end position");

test(() => {
  target.style.scrollSnapAlign = "start";
  target.style.transform = "translateX(-100px)";
  scroller.scrollTo(10, 0);
  assert_equals(scroller.scrollLeft, 0);
  assert_equals(scroller.scrollTop, 0);
}, "Snaps to visible top left position of the transformed box");

</script>