Mockito单元测试中如何验证RestClientException异常？

你当前的测试代码无法触发RestClientException，原因是你让RestTemplate返回了HttpStatus.SERVICE_UNAVAILABLE的响应实体，但这种场景下RestTemplate不会抛出异常，只会正常返回响应，被测试类只会进入else分支打印错误日志，不会触发catch块的异常逻辑。

要验证RestClientException，需要让RestTemplate在调用exchange方法时直接抛出该异常，修改后的测试代码如下：

@Test
void test_update_customer_in_ath0_server_error() {
    // given
    doThrow(new RestClientException("模拟服务调用异常"))
            .when(restTemplate).exchange(any(), eq(HttpMethod.PATCH), any(HttpEntity.class), (Class<String>)any());

    // then - 验证方法抛出指定异常
    Assertions.assertThrows(RestClientException.class, () -> {
        idpFacadeClient.updateCustomerFirstNameInIdp(updateRecordsDto);
    });
    
    // 验证RestTemplate的exchange方法被正确调用
    verify(restTemplate).exchange(any(), eq(HttpMethod.PATCH), argThat(this::verifyUpdatedCustomerBody), (Class<String>)any());
}

关键修改说明 #

• 用doThrow替代doReturn，让RestTemplate调用exchange时直接抛出RestClientException
• 通过Assertions.assertThrows验证被测试方法确实会抛出目标异常
• 保留原有的verify逻辑，确保调用exchange时使用了正确的参数

原测试类代码 #

@Test
void test_update_customer_in_ath0_server_error(){
    //given
    ResponseEntity<String> responseEntity = new ResponseEntity<>(HttpStatus.SERVICE_UNAVAILABLE);
    doReturn(responseEntity)
            .when(restTemplate).exchange(any(), eq(HttpMethod.PATCH), any(HttpEntity.class), (Class<String>)any());

    idpFacadeClient.updateCustomerFirstNameInIdp(updateRecordsDto);

    //then
    verify(restTemplate).exchange(any(), eq(HttpMethod.PATCH), argThat(this::verifyUpdatedCustomerBody), (Class<String>)any());
}

被Mock类代码 #

try {
    response = restTemplate.exchange(URI.create(idpFacadeUpdateUrl), HttpMethod.PATCH, entity,  String.class);
    if (response.getStatusCode() == HttpStatus.OK) {
        log.info("customer first name update success {} with status {}", customerUpdateRecordsDto.getFirstName(), response.getStatusCode());
    }else {
        log.error("Customer first name update failed in IDP for {} with status {}", customerUpdateRecordsDto.getFirstName(), response.getStatusCode());
    }
} catch (RestClientException e) {
    throw new RestClientException("Idp facade API error for user first name " + customerUpdateRecordsDto.getFirstName(), e);
}

内容的提问来源于stack exchange，提问作者clement mensah