speculation-rules/prerender/resources/web-serial.https.html

<!DOCTYPE html>
<script src="/common/utils.js"></script>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/speculation-rules/prerender/resources/utils.js"></script>
<script src="/speculation-rules/prerender/resources/deferred-promise-utils.js"></script>
<script>

const params = new URLSearchParams(location.search);

// The main test page (restriction-web-serial.https.html) loads the
// initiator page, then the initiator page will prerender itself with the
// `prerendering` parameter.
const isPrerendering = params.has('prerendering');

if (!isPrerendering) {
  loadInitiatorPage();
} else {
  const prerenderEventCollector = new PrerenderEventCollector();
  // The spec, https://wicg.github.io/nav-speculation/prerendering.html#patch-serial,
  // says that Web Serial API has delay while prerendering for
  // requestPort(). As this test uses getPorts(), it's a tentative test.
  prerenderEventCollector.start(
      navigator.serial.getPorts(), 'navigator.serial.getPorts');
}

</script>