@Test(expected = IllegalStateException.class)
  public void testCantSendWithoutConnecting() throws Exception {
    selector.poll(1000L, asList(createSend("testCantSendWithoutConnecting_test", "test")));
  }
Sending a request to a node without an existing connection should result in an exception
ambry-network/src/test/java/com/github/ambry/network/SelectorTest.java