chromium/third_party/blink/web_tests/animations/svg/clear-svg-animation-effects.html

<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<svg>
  <stop id="target" offset="1"/>
</svg>
<script>
var asyncHandle = async_test('SVG Attributes should return to their base values after animations have stopped applying.');

var animation = target.animate([
  {'svg-offset': '0'},
  {'svg-offset': '0.5'},
], 1000);
animation.pause();
animation.currentTime = 500;

requestAnimationFrame(() => {
  asyncHandle.step(() => {
    assert_equals(target.offset.animVal, 0.25, 'Animation is in effect.');
  });
  animation.cancel();
  requestAnimationFrame(() => {
    asyncHandle.step(() => {
      assert_equals(target.offset.animVal, 1, 'Animation is no longer in effect.');
    });
    asyncHandle.done();
  });
});
</script>