### Question:
Sample3Controller { @PostMapping("/sample3") public String save(@RequestBody PointDto requestDto){ messagingTemplate.convertAndSend("sample3", requestDto); return "success"; }  @PostMapping("/sample3") String save(@RequestBody PointDto requestDto);  }### Answer:
@Test public void Ack_fails_Go_to_the_dlq() throws Exception { PointDto requestDto = PointDto.builder() .userId(1L) .savePoint(1000L) .description("buy laptop") .build(); given(pointRepository.save(any())) .willThrow(new IllegalArgumentException("fail")); pointListener.setCountDownLatch(new CountDownLatch(1)); messagingTemplate.convertAndSend("sample3", requestDto); assertTrue(this.pointListener.getCountDownLatch().await(15, TimeUnit.SECONDS)); }