LayoutTests/workers/worker-user-gesture.html

<!DOCTYPE html>
<html>
<head>
<script src="../resources/js-test.js"></script>
<script>
description("Passes a User Gesture through postMessage() to a worker context; press any key, click, or tap to continue.");
window.jsTestIsAsync = true;

function runTest() {
    const mc = new MessageChannel();
    const w = new Worker("worker-user-gesture.js");
    w.postMessage('hello worker');
    w.onmessage = event => {
        if (window.internals) {
            if (internals.isProcessingUserGesture())           
                testPassed('User Gesture was propagated through postMessage and back.');
            else
                testFailed('User Gesture was not propagated through postMessage and back.')
            finishJSTest();
            return;
        }

        navigator.clipboard.writeText(event.data).then(() => {
            testPassed('User Gesture was propagated through postMessage and back.')
        }).catch(e => {
            testFailed('User Gesture was not propagated through postMessage and back.')
        }).finally(finishJSTest);
    };
}

window.addEventListener('load', event => {
    if (window.internals)
        internals.withUserGesture(runTest);
    else
        ['keypress', 'click', 'touchend'].forEach(eventName => window.addEventListener(eventName, runTest, {once: true}));
});

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