chromium/third_party/blink/web_tests/xmlviewer/sitemap.html

<html>
<head>
<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>
<script>
async_test((t) => {
  let xmlWindow;

  t.add_cleanup(() => { xmlWindow.close(); });

  function checkConvertedDOM() {
    var sourcePretty = xmlWindow.document.getElementsByClassName('pretty-print')[0];

    if (!sourcePretty || !sourcePretty.innerText) {
      requestAnimationFrame(t.step_func(checkConvertedDOM));
      return;
    }

    assert_true(sourcePretty.textContent.includes('http://example.com/test.html'));
    assert_true(sourcePretty.textContent.includes('<lastmod>2020-02-05</lastmod>'));

    t.done();
  }

  window.addEventListener("load", (e) => {
    xmlWindow = window.open('resources/sitemap.xml', 'XMLViewerTestWindow');
    xmlWindow.onload = t.step_func(checkConvertedDOM);
  });
}, 'XMLTreeConverted');
</script>
</head>
<body>
</body>
</html>