@Test
public void call_receive() {

    // prepare
    ReceiveEvent event = mock(ReceiveEvent.class);
    Object msg = mock(Object.class);
    when(event.getMessage()).thenReturn(msg);
    when(event.getSession()).thenReturn(session);
    // run
    caller.visit(event);
    // verify
    verify(event).getSession();
    verify(event).getMessage();
    verify(session).getService();
    verify(service).getIoHandler();
    verify(handler).messageReceived(session, msg);
    verifyNoMoreInteractions(session, event, handler);
}