LayoutTests/imported/w3c/web-platform-tests/workers/SharedWorker-MessageEvent-source.any.js

// META: global=sharedworker
const t = async_test("Make sure that MessageEvent.source is properly set in connect event.");
onconnect = t.step_func_done((event) => {
  assert_equals(event.__proto__, MessageEvent.prototype);
  assert_equals(event.source, event.ports[0]);
});