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Test Info: Warnings

<!DOCTYPE html>
<title>Test MediaSource object and handle creation, with MediaSource in dedicated worker</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="mediasource-message-util.js"></script>
async_test(t => {
// Fail fast if MSE-in-Workers is not supported.
assert_true(MediaSource.hasOwnProperty("canConstructInDedicatedWorker"), "MediaSource hasOwnProperty 'canConstructInDedicatedWorker'");
assert_true(MediaSource.canConstructInDedicatedWorker, "MediaSource.canConstructInDedicatedWorker");
assert_true(window.hasOwnProperty("MediaSourceHandle"), "window must have MediaSourceHandle visibility");
let worker = new Worker("mediasource-worker-play.js");
worker.onmessage = t.step_func(e => {
let subject =;
assert_true(subject != undefined, "message must have a subject field");
switch (subject) {
case messageSubject.ERROR:
assert_unreached("Worker error: " +;
case messageSubject.HANDLE:
const handle =;
assert_not_equals(handle, null, "must have a non-null MediaSourceHandle");
assert_true(handle instanceof MediaSourceHandle, "must be a MediaSourceHandle");
assert_unreached("Unexpected message subject: " + subject);
}, "Test main context receipt of postMessage'd MediaSourceHandle from DedicatedWorker MediaSource");
test(t => {
assert_true(window.hasOwnProperty("MediaSourceHandle"), "window must have MediaSourceHandle");
}, "Test main-thread has MediaSourceHandle defined");
test(t => {
// Note, MSE spec may eventually describe how a main-thread MediaSource can
// attach to an HTMLMediaElement using a MediaSourceHandle. For now, we
// ensure that the implementation of this is not available per current spec.
"handle" in MediaSource.prototype,
"window MediaSource must not have handle in prototype");
}, "Test main-thread MediaSource does not have handle getter");
if (MediaSource.hasOwnProperty("canConstructInDedicatedWorker") && MediaSource.canConstructInDedicatedWorker === true) {
// If implementation claims support for MSE-in-Workers, then fetch and run
// some tests directly in another dedicated worker and get their results
// merged into those from this page.
fetch_tests_from_worker(new Worker("mediasource-worker-handle.js"));
} else {
// Otherwise, fetch and run a test that verifies lack of support of
// MediaSource construction in another dedicated worker.
fetch_tests_from_worker(new Worker("mediasource-worker-must-fail-if-unsupported.js"));