public void _testErrorCommand() throws Exception {
    Command nonexisCmd =
        new Command() {

          @Override
          public boolean decode(MemcachedTCPSession session, ByteBuffer buffer) {
            return decodeError(ByteUtils.nextLine(buffer));
          }

          @Override
          public void encode() {
            ioBuffer = IoBuffer.wrap(ByteBuffer.wrap("test\r\n".getBytes()));
          }
        };
    nonexisCmd.setKey("test");
    nonexisCmd.setLatch(new CountDownLatch(1));
    memcachedClient.getConnector().send(nonexisCmd);
    // this.memcachedClient.flushAll();
    nonexisCmd.getLatch().await();

    assertNotNull(nonexisCmd.getException());
    assertEquals(
        "Nonexist command,check your memcached version please.",
        nonexisCmd.getException().getMessage());
    assertTrue(nonexisCmd.getException() instanceof UnknownCommandException);

    memcachedClient.set("name", 0, "dennis");
    assertEquals("dennis", memcachedClient.get("name"));
  }