@Test(expected = RuntimeException.class)
public void testStoppedSender()
    throws NoSuchFieldException, SecurityException, IllegalArgumentException,
    IllegalAccessException {

  networks = createNetworks(2);
  Field f1 = networks.get(1).getClass().getDeclaredField("senders");
  f1.setAccessible(true);
  @SuppressWarnings("unchecked")
  Sender sender = ((HashMap<Integer, Sender>) f1.get(networks.get(1))).get(2);
  sender.stop();
  networks.get(1).send(2, new byte[] { 0x01 });
  f1.setAccessible(false);
}