chromium/third_party/blink/web_tests/http/tests/security/contentSecurityPolicy/1.1/form-action-blocked-when-target-cross-site-window.html

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Security-Policy" content="form-action 'none'">
<script>
    if (window.testRunner) {
        testRunner.dumpAsText();
        testRunner.waitUntilDone();
        testRunner.setPopupBlockingEnabled(false);
    }

    // Open a new window with the name matching form.target attribute below.
    let w = window.open(
        'http://localhost:8080/security/resources/post-done-to-opener.html',
        'namedCrossSiteWindow')
     Promise.all([
         new Promise(resolve => {
             window.addEventListener('message', msg => {
                 if (msg.source === w) resolve()
             });
         }),
         new Promise(resolve =>
             window.addEventListener('load', _ => resolve())),
     ]).then(_ => {
         document.getElementById('theform').addEventListener('submit', function(e) {
            console.log('submit event fired.');
        });

        setTimeout(function() {
            document.getElementById('submit').click();
        }, 0);
    });

    document.addEventListener('securitypolicyviolation', function(e) {
        console.log('securitypolicyviolation event fired.');
        console.log('securitypolicyviolation_event.documentURI=' + e.documentURI);
        console.log('securitypolicyviolation_event.blockedURI=' + e.blockedURI);
        console.log('securitypolicyviolation_event.violatedDirective=' + e.violatedDirective);
        setTimeout(function() {
            testRunner.notifyDone();
        }, 0);
    });
</script>
</head>
<body>
    <form action='/navigation/resources/form-target.pl' id='theform'
          method='post' target="namedCrossSiteWindow">
        <input type='text' name='fieldname' value='fieldvalue'>
        <input type='submit' id='submit' value='submit'>
    </form>

    <p>Tests that blocking form actions works correctly. If this test passes, you will see a console error, and will not see a page indicating a form was POSTed.</p>
</body>
</html>