css/css-conditional/container-queries/scroll-state/scroll-state-scrollable-layout-change.html

<!DOCTYPE html>
<title>@container: scroll-state(scrollable) layout change</title>
<link rel="help" href="https://drafts.csswg.org/css-conditional-5/#scrollable">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/css/css-conditional/container-queries/support/cq-testcommon.js"></script>
<script src="/css/css-transitions/support/helper.js"></script>
<style>
  #scroller {
    container-type: scroll-state;
    overflow: auto;
    width: 100px;
    height: 100px;
  }
  #target {
    width: 200px;
    height: 200px;
    --scrollable: no;
    @container scroll-state(scrollable) {
      --scrollable: yes;
    }
  }
  #target.small {
    width: 10px;
    height: 10px;
  }
</style>
<div id="scroller">
  <div id="target"></div>
</div>
<script>
  setup(() => assert_implements_scroll_state_container_queries());

  promise_test(async t => {
    await waitForAnimationFrames(2);
    assert_equals(getComputedStyle(target).getPropertyValue("--scrollable"), "yes");
  }, "Check scroll-state(scrollable) initially matching");

  promise_test(async t => {
    t.add_cleanup(async () => target.className = "");
    target.className = "small";
    await waitForAnimationFrames(2);
    assert_equals(getComputedStyle(target).getPropertyValue("--scrollable"), "no",
                  "#target not scrollable #scroller");
    target.className = "";
    await waitForAnimationFrames(2);
    assert_equals(getComputedStyle(target).getPropertyValue("--scrollable"), "yes",
                  "#target scrollable #scroller again");
  }, "Check scroll-state(scrollable) not matching after layout change no longer causing overflow");

</script>