test_use_tree_cycle.html

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<!doctype html>

<title>Test for bug 1531333</title>

<script src="/tests/SimpleTest/SimpleTest.js"></script>

<link rel="stylesheet" href="/tests/SimpleTest/test.css">

<style>

  symbol { display: block }

</style>

<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="10" height="10">

  <symbol id="svg-sprite" viewBox="0 0 133 230866">

    <title>svg-sprite</title>

    <symbol id="svg-sprite" viewBox="0 0 133 230866">

        <title>svg-sprite</title>

        <use xlink:href="#svg-sprite" width="500" height="500" />

    </symbol>

    <use xlink:href="#svg-sprite" y="1601" width="133" height="228958" />

  </symbol>

  <use xlink:href="#svg-sprite" y="1601" width="133" height="230866" />

</svg>

<script>

function countUseElements(subtreeRoot) {

  if (!subtreeRoot)

    return 0;

  let i = 0;

  for (const use of subtreeRoot.querySelectorAll("use"))

    i += 1 + countUseElements(SpecialPowers.wrap(use).openOrClosedShadowRoot);

  return i;

SimpleTest.waitForExplicitFinish();

onload = function() {

  document.body.offsetTop;

  // The three in the document, plus the two created from the element that's

  // not in the <symbol> subtree.

  is(countUseElements(document), 5, "Shouldn't create more than 5 use elements");

  SimpleTest.finish();

</script>