@Test(expected = IllegalArgumentException.class)
 public void sendMessageWhileClosed() throws NoSuchAlgorithmException, URISyntaxException {
   TestMessageHandler handler = new TestMessageHandler();
   Configuration configuration =
       new Configuration(handler, "ws://echo.websocket.org", SSLContext.getDefault());
   WebSocket socket = new WebSocket(configuration);
   socket.sendMessage("some random message");
 }