third_party/web_platform_tests/fetch/api/request/request-keepalive.html

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Request keepalive</title>
<meta name="help" href="https://fetch.spec.whatwg.org/#request">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/common/utils.js"></script>
<script src="/common/get-host-info.sub.js"></script>
</head>
<body>
<script>
test(() => {
  assert_false(new Request('/').keepalive, 'default');
  assert_true(new Request('/', {keepalive: true}).keepalive, 'true');
  assert_false(new Request('/', {keepalive: false}).keepalive, 'false');
  assert_true(new Request('/', {keepalive: 1}).keepalive, 'truish');
  assert_false(new Request('/', {keepalive: 0}).keepalive, 'falsy');
}, 'keepalive flag');

test(() => {
  const init = {method: 'POST', keepalive: true, body: new ReadableStream()};
  assert_throws('TypeError', () => {new Request('/', init)});
}, 'keepalive flag with stream body');
</script>
</body>
</html>