no-assert-mixing-variables-and-animation.html

<!DOCTYPE html>
<script src="../../../resources/testharness.js"></script>
<script src="../../../resources/testharnessreport.js"></script>

<style>
body {
  --b: 420px;
}
#element {
  --a: var(--b);
  width: 100px;
  height: 100px;
  background-color: red;
  transition: width 1s;
}

#element.triggered {
  width: var(--a);
}
</style>

<div id='element'></div>

<script>
var test = async_test("this test passes if it doesn't assert");

requestAnimationFrame(x => {
  element.classList.add('triggered');
  requestAnimationFrame(x => {
    requestAnimationFrame(x => {
      requestAnimationFrame(x => {
        requestAnimationFrame(x => {
          test.done();
        })
      })
    })
  })
});
</script>

chromium/third_party/blink/web_tests/fast/css/variables/no-assert-mixing-variables-and-animation.html