<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <script src="../../resources/testharness.js"></script>
    <script src="../../resources/testharnessreport.js"></script>
    <script>
    
    promise_test(async (test) => {
    
        if (window.testRunner)
            testRunner.setUserMediaPermission(true);

        let devices1 = await navigator.mediaDevices.enumerateDevices();

        let eventCount = 0;
        await new Promise((resolve, reject) => {
            navigator.mediaDevices.ondevicechange = (evt) => {
                ++eventCount;
                resolve();
            }

            setTimeout(() => {
                reject("navigator.mediaDevices.ondevicechange took too long")
            }, 4000);

            navigator.mediaDevices.getUserMedia({ audio:true, video:true });
        });

        let devices2 = await navigator.mediaDevices.enumerateDevices();
        assert_true(devices1.length < devices2.length, "more devices revealed after gUM");
        assert_equals(eventCount, 1, "one event fired");

    }, "'devicechange' event fired after getUserMedia() if enumerateDevices() previously returned filtered list");

    </script>
</head>
<body>
</body>
</html>