sousa-gecko/testing/web-platform/tests/html/semantics/links/hyperlink-auditing/headers.optional.html

<!DOCTYPE html>
<meta charset="utf-8">
<meta name=timeout content=long>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/common/utils.js"></script>

<iframe id="i" src="/common/blank.html"></iframe>

<!-- Test is optional because hyperlink auditing is optional. -->

<script>
promise_test(async t => {
  await new Promise(resolve => window.onload = resolve);

  const id = token();

  const el = document.createElement("a");
  el.ping = new URL(`resources/stash-headers.py?id=${id}`, location.href); // this will be a POST
  el.href = "/common/blank.html?1";

  i.contentDocument.body.append(el);
  el.click();

  let headers;
  await pollForConditionFunc(t, async () => {
    const res = await fetch(el.ping); // this will be a GET
    const json = await res.json();

    if (json !== "no headers yet") {
      headers = json;
      return true;
    }
    return false;
  });

  assert_equals(headers["content-type"], "text/ping", "content-type");
  assert_equals(headers["ping-from"], i.src, "ping-from");
  assert_equals(headers["ping-to"], el.href, "ping-to");
});

async function pollForConditionFunc(t, func, timeout = 3000, interval = 100) {
  let remaining = Math.ceil(timeout / interval);

  while (remaining > 0) {
    --remaining;
    await new Promise(resolve => t.step_timeout(resolve, interval));

    if (await func()) {
      return;
    }
  }

  assert_true(false, "Condition never became true");
}
</script>