function message_from_port(port) {
  return new Promise(resolve => {
    port.onmessage = e => resolve(e.data);
  });
}

promise_test(async t => {
  const run_result = 'worker_OK';
  const blob_contents = 'self.postMessage("' + run_result + '");';
  const blob = new Blob([blob_contents]);
  const url = URL.createObjectURL(blob);

  const worker = new Worker(url);
  const reply = await message_from_port(worker);
  assert_equals(reply, run_result);
}, 'Creating a dedicated worker from a blob URL works.');

promise_test(async t => {
  const run_result = 'worker_OK';
  const blob_contents = 'self.postMessage("' + run_result + '");';
  const blob = new Blob([blob_contents]);
  const url = URL.createObjectURL(blob);

  const worker = new Worker(url);
  URL.revokeObjectURL(url);
  const reply = await message_from_port(worker);
  assert_equals(reply, run_result);
}, 'Creating a dedicated worker from a blob URL works immediately before revoking.');