@Test(expected = IllegalStateException.class)
  public void testCantSendWithInProgress() throws Exception {
    String connectionId = blockingConnect();
    selector.poll(1000L, asList(createSend(connectionId, "test1"), createSend(connectionId, "test2")));
  }
Sending a request with one already in flight should result in an exception
ambry-network/src/test/java/com/github/ambry/network/SelectorTest.java