模擬 RestTemplate API 調用

Question

我需要對使用 RestTemplate 進行外部 API 調用的方法進行單元測試，我試圖模擬外部 API 的響應並斷言該方法的返回值。 我還嘗試使用MockRestServiceServer和@InjectMocks模擬響應，但無法獲得預期的 output 並且它進行了實際的 API 調用。 任何指導將不勝感激。

---

測試用例

public class SnowFlakeServiceTest {

  private final RestTemplate restTemplate = Mockito.mock(RestTemplate.class);
  private final SnowFlakeServiceImpl snowFlakeService = new SnowFlakeServiceImpl(restTemplate);

  @Test
  public void testGetAccessToken() {

    SnowFlakeTokenDTO snowFlakeTokenDTO = new SnowFlakeTokenDTO();
    snowFlakeTokenDTO.setAccessToken("fakeAccessToken");
    snowFlakeTokenDTO.setExpiresIn(600);
    snowFlakeTokenDTO.setTokenType("Bearer");

    ResponseEntity<SnowFlakeTokenDTO> responseEntity = new ResponseEntity<>(snowFlakeTokenDTO, HttpStatus.OK);
    when(restTemplate.exchange(
        ArgumentMatchers.anyString(),
        ArgumentMatchers.any(HttpMethod.class),
        ArgumentMatchers.any(),
        ArgumentMatchers.<Class<SnowFlakeTokenDTO>>any()))
        .thenReturn(responseEntity);

    assertThat(snowFlakeService.getAccessToken()).isEqualTo(snowFlakeTokenDTO.getAccessToken());
  }

}

---

SnowFlakeServiceImpl.java

 private final RestTemplate restTemplate;

  public SnowFlakeServiceImpl(RestTemplate restTemplate) {
    this.restTemplate = restTemplate;
  }

@Override
  public String getAccessToken() {
    log.debug("token requested id : {}, secret :{}", snowFlakeClientId, snowFlakeClientSecret);
    try {
      HttpHeaders httpHeaders = new HttpHeaders();
      httpHeaders.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
      httpHeaders.setBasicAuth(snowFlakeClientId, snowFlakeClientSecret);

      MultiValueMap<String, String> requestBody = new LinkedMultiValueMap<>();
      requestBody.add("grant_type", snowFlakeRefreshTokenGrantType);
      requestBody.add("refresh_token", refreshToken);
      requestBody.add("redirect_uri", snowFlakeRedirectUrl);

      HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(requestBody, httpHeaders);
      ResponseEntity<SnowFlakeTokenDTO> response = restTemplate.exchange(snowFlakeTokenRequestUrl, HttpMethod.POST, request, SnowFlakeTokenDTO.class);
      log.debug("response: {}", response);
      return Objects.requireNonNull(response.getBody()).getAccessToken();
    } catch (Exception e) {
      log.debug("error: {}", ExceptionUtils.getRootCauseMessage(e));
      throw new ErrorDTO(Status.BAD_REQUEST, accessTokenErrorMessage, e.getMessage());
    }
  }

---

RestTemplateConigurations.java

@Configuration
public class RestTemplateConfiguration {

  @Value("${rest-template.connection.timeout}")
  private int connectionTimeout;

  @Value("${rest-template.read.timeout}")
  private int readTimeout;

  @Bean
  public RestTemplate restTemplate(RestTemplateBuilder builder) {
    return builder
        .setConnectTimeout(Duration.ofMillis(connectionTimeout))
        .setReadTimeout(Duration.ofMillis(readTimeout))
        .build();
  }
}

---

Spring 引導：2.5.4
Java：11
Junit：5

Answer 1

每次調用getAccessToken()方法時都不需要新的RestTemplate 。 它應該由 Spring 注入：

@Service
public class SnowFlakeService {

  private RestTemplate restTemplate;

  public ServiceImpl(RestTemplate restTemplate) {
      this.restTemplate = restTemplate;
  }

  @Override
  public String getAccessToken() {
    try {
      HttpHeaders httpHeaders = new HttpHeaders();
      httpHeaders.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
      httpHeaders.setBasicAuth(snowFlakeClientId, snowFlakeClientSecret);

      MultiValueMap<String, String> requestBody = new LinkedMultiValueMap<>();
      requestBody.add("grant_type", snowFlakeRefreshTokenGrantType);
      requestBody.add("refresh_token", refreshToken);
      requestBody.add("redirect_uri", snowFlakeRedirectUrl);

      HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(requestBody, httpHeaders);
      ResponseEntity<SnowFlakeTokenDTO> response = restTemplate.exchange(snowFlakeTokenRequestUrl, HttpMethod.POST, request, SnowFlakeTokenDTO.class);
      
      return Objects.requireNonNull(response.getBody()).getAccessToken();
    } catch (Exception e) {
      throw new ErrorDTO(Status.BAD_REQUEST, accessTokenErrorMessage, e.getMessage());
    }
  }
}

最重要的是，您實際上不需要@SpringBootTest來測試SnowFlakeService 。 常規的單元測試幾乎沒問題。

public class SnowFlakeServiceTest {

  private RestTemplate restTemplate = Mockito.mock(RestTemplate.class);
  private SnowFlakeService snowFlakeService = new SnowFlakeService(restTemplate);

  @Test
  public void testGetAccessToken() {
    SnowFlakeTokenDTO snowFlakeTokenDTO = new SnowFlakeTokenDTO();
    snowFlakeTokenDTO.setAccessToken("fakeAccessToken");
    snowFlakeTokenDTO.setExpiresIn(600);
    snowFlakeTokenDTO.setTokenType("Bearer");

    ResponseEntity<SnowFlakeTokenDTO> responseEntity = new ResponseEntity<>(snowFlakeTokenDTO, HttpStatus.OK);
    when(restTemplate.exchange(
        ArgumentMatchers.anyString(),
        ArgumentMatchers.any(HttpMethod.class),
        ArgumentMatchers.any(),
        ArgumentMatchers.<Class<SnowFlakeTokenDTO>>any()))
        .thenReturn(responseEntity);

    assertThat(snowFlakeService.getAccessToken()).isEqualTo(snowFlakeTokenDTO.getAccessToken());
  }

}

Answer 2

您可以嘗試以下方法，使用any(RequestEntity.class)而不是ArgumentMatchers

RestTemplate restTemplate = mock(RestTemplate.class);

ResponseEntity<SnowFlakeTokenDTO> refreshResponse = ResponseEntity.of(SnowFlakeTokenDTO());

doReturn(refreshResponse).when(restTemplate).exchange(any(RequestEntity.class), eq(SnowFlakeTokenDTO.class));