chromium/third_party/blink/web_tests/external/wpt/svg/animations/reinserting-svg-into-document.html

<!doctype html>
<title>Reinserting SVG animation into document should continue the animation</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<svg id="svg">
  <rect id="rect" x="0" y="0" width="20" height="20">
    <animate attributeName="x" begin="0" from="0" to="90" dur="3s" fill="freeze"/>
  </rect>
</svg>
<script>
async_test(t => {
  const svg = document.getElementById('svg');

  // The timeline starts after 'load'.
  window.onload = t.step_func(() => {
    svg.setCurrentTime(1);

    t.step_timeout(() => {
      assert_not_equals(svg.getCurrentTime(), 0, 'started');

      // Removing and re-adding the SVG shouldn't change anything about the
      // underlying animation.
      document.body.removeChild(svg);
      document.body.appendChild(svg);

      // The SVG animation will continue after the next frame runs.
      window.requestAnimationFrame(t.step_func_done(() => {
        const rect = document.getElementById('rect');
        assert_greater_than_equal(svg.getCurrentTime(), 1);
        assert_greater_than_equal(rect.x.animVal.value, 30);
        svg.setCurrentTime(2);
        assert_approx_equals(rect.x.animVal.value, 60, 1);
      }));
    });
  });
});
</script>