third_party/blink/web_tests/external/wpt/css/css-properties-values-api/animation/custom-property-transition-image.html

<!DOCTYPE html>
<link rel="help" href="https://drafts.css-houdini.org/css-properties-values-api-1">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="../resources/utils.js"></script>
<div id="target"></div>
<script>

transition_test({
  syntax: "<image>",
  from: 'url("https://example.com/from")',
  to: 'url("https://example.com/to")',
  expected: 'url("https://example.com/to")',
}, 'A custom property of type <image> can yield a CSS Transition');

</script>