speculation-rules/prerender/restriction-message-boxes.https.html

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

<body>
<script>
setup(() => assertSpeculationRulesIsSupported());

function runTest(test_file, expectation, description) {
  promise_test(async t => {
    const uid = token();
    const bc = new PrerenderChannel('prerender-channel', uid);
    t.add_cleanup(_ => bc.close());

    const gotMessage = new Promise(resolve => {
      bc.addEventListener('message', e => {
        resolve(e.data);
      }, {
        once: true
      });
    });

    // Open a new window to test the message box.
    window.open(`${test_file}&uid=${uid}`, '_blank', 'noopener');

    // Wait for the message from the prerendering page.
    assert_equals(await gotMessage, expectation);
  }, description);
}

// Test that a page invokes the alert modal during prerendering.
runTest(
    'resources/message-boxes.html?alert',
    'no block',
    'alert() does not display the modal and returns immediately');

// Test that a page invokes the confirm modal during prerendering.
runTest(
    'resources/message-boxes.html?confirm',
    'the return value is no',
    'confirm() does not display the modal and returns immediately');

// Test that a page invokes the prompt modal during prerendering.
runTest(
    'resources/message-boxes.html?prompt',
    'the return value is null',
    'prompt() does not display the modal and returns immediately');
</script>