<!DOCTYPE html>
<body>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
function with_iframe(url, allow) {
    let frame = document.createElement('iframe');
    frame.src = url;
    frame.setAttribute('allow', allow);
    return new Promise(resolve => {
        frame.onload = () => { resolve(frame); };
        document.body.appendChild(frame);
    });
}

promise_test(async () => {
    let frame1 = await with_iframe("resources/", "microphone:'none'; camera:'none'");
    let devices = await frame1.contentWindow.navigator.mediaDevices.enumerateDevices();
    assert_equals(devices.length, 0);

    frame1.removeAttribute('allow');
    devices = await frame1.contentWindow.navigator.mediaDevices.enumerateDevices();
    assert_not_equals(devices.length, 0);
}, "allow attribute can be updated dynamically");
</script>
</body>