### Question:
MessagePump { public void shutdown() { if (!m_shutdownTriggered) { m_shutdownTriggered = true; m_receiver.shutdown(); m_sender.shutdown(); m_executor.shutdownNow(); } } MessagePump(Receiver receiver, Sender sender, int numberOfThreads); void start(); void shutdown();  }### Answer:
@Test public void testShutdownIfReceiverShutdown() throws Exception { m_sender.shutdown(); assertEquals(null, m_intermediateReceiver.waitForMessage()); assertEquals(null, m_receiver.waitForMessage()); }