offscreencanvas.transferrable-webgl-exception.html

<!DOCTYPE html>
<html>
<head>
<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
</head>
<body>

<script id="myWorker" type="text/worker">

function test1(offscreenCanvas)
{
    return offscreenCanvas.width == 10 && offscreenCanvas.height == 10;
}

self.onmessage = function(e) {
    switch(e.data.msg) {
        case 'test1':
            self.postMessage(test1(e.data.data));
            break;
    }
};

</script>
<script>
function makeWorker(script)
{
    var blob = new Blob([script]);
    return new Worker(URL.createObjectURL(blob));
}

test(function() {
    function testException(contextType) {
        var worker = makeWorker(document.getElementById("myWorker").textContent);
        var offscreenCanvas = new OffscreenCanvas(10, 10);
        var ctx = offscreenCanvas.getContext(contextType);
        assert_throws_dom("InvalidStateError", function() {
            worker.postMessage({offscreenCanvas}, [offscreenCanvas]);
        });
    }
    testException('webgl');
}, "Test that transfer an OffscreenCanvas that has a context throws exception.");

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

chromium/third_party/blink/web_tests/fast/canvas-api/offscreencanvas.transferrable-webgl-exception.html