mozilla-release/testing/web-platform/tests/battery-status/battery-iframe.https.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>Battery Test: navigator.getBattery() is not allowed in non top-level browsing context</title>
<link rel="author" title="Intel" href="http://www.intel.com">
<link rel="help" href="https://www.w3.org/TR/battery-status/">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id="log"></div>
<iframe id="blank" src="about:blank" style="display: none"></iframe>
<script>

function load_iframe(iframe, src) {
  return new Promise((resolve, reject) => {
    iframe.onload = () => resolve(iframe);
    iframe.src = src;
  });
}

promise_test(t => {
  var iframe = document.getElementById('blank');
  var src = 'support-iframe.html';
  return load_iframe(iframe, src)
    .then(iframe => promise_rejects(t, 'SecurityError',
                                    iframe.contentWindow.navigator.getBattery()));
}, "throw a 'SecurityError' when invoking navigator.getBattery() within iframe");

</script>