RestTemplate 和 RetryTemplate 的 JAVA Mockito 单元测试

Question

我目前正在为以下方法编写单元测试

@Autowired
private RequestConfig requestConfig;

@Autowired
private RetryTemplate retryTemplate;

public ResponseEntity<String> makeGetServiceCall(String serviceUrl) throws Exception {
    try {
        return retryTemplate.execute(retryContext -> {

            RestTemplate restTemplate = new RestTemplate();
            HttpHeaders headers = requestConfig.createHttpHeaders();
            HttpEntity<String> entity = new HttpEntity<String>("parameters", headers);
            ResponseEntity<String> response = restTemplate.exchange(serviceUrl, HttpMethod.GET, entity, String.class);
            return response;

        });
    } catch (Exception e) {
        throw new Exception("Generic exception while makeGetServiceCall due to" + e + serviceUrl);
    }
}

更新的方法:

@Autowired
private RequestConfig requestConfig;

@Autowired
private RetryTemplate retryTemplate;

@Autowired
private RestTemplate restTemplate;

public ResponseEntity<String> makeGetServiceCall(String serviceUrl) throws Exception {
    try {
        return retryTemplate.execute(retryContext -> {

            HttpHeaders headers = requestConfig.createHttpHeaders();
            HttpEntity<String> entity = new HttpEntity<String>("parameters", headers);
            ResponseEntity<String> response = restTemplate.exchange(serviceUrl, HttpMethod.GET, entity, String.class);
            return response;

        });
    } catch (Exception e) {
        throw new Exception("Generic exception while makeGetServiceCall due to" + e + serviceUrl);
    }
}

我尝试了所有的可能性，但我无法做到正确。这是我的以下测试。

@Mock
private RestTemplate restTemplate;

@Mock
public RequestConfig requestConfig;

@InjectMocks
private RetryTemplate retryTemplate;

ServiceRequest serviceRequest;


@Test
public void makeGetServiceCall() throws Exception {
    String url = "http://localhost:8080";
    RetryTemplate mockRetryTemplate = Mockito.mock(RetryTemplate.class);
    RestTemplate mockRestTemplate = Mockito.mock(RestTemplate.class);
    ResponseEntity<String> myEntity = new ResponseEntity<>(HttpStatus.ACCEPTED);
    Mockito.when(mockRetryTemplate.execute(ArgumentMatchers.any(RetryCallback.class), ArgumentMatchers.any(RecoveryCallback.class), ArgumentMatchers.any(RetryState.class))).thenReturn(myEntity);

    Mockito.when(mockRestTemplate.exchange(
            ArgumentMatchers.eq(url),
            ArgumentMatchers.eq(HttpMethod.GET),
            ArgumentMatchers.<HttpEntity<String>>any(),
            ArgumentMatchers.<Class<String>>any())
    ).thenReturn(myEntity);

    ResponseEntity<String> response = serviceRequest.makeGetServiceCall(url);
    Assert.assertEquals(myEntity, response);
}

更新的测试用例:

 @Mock
public RequestConfig requestConfig;

@Mock
private RestTemplate restTemplate;

@Mock
private RetryTemplate retryTemplate;

@InjectMocks
ServiceRequest serviceRequest;

@Test
public void makeGetServiceCall() throws Exception {
    //given:
    String url = "http://localhost:8080";

    when(requestConfig.createHttpHeaders()).thenReturn(null);
    ResponseEntity<String> myEntity = new ResponseEntity<>( HttpStatus.ACCEPTED);
    when(retryTemplate.execute(any(RetryCallback.class), any(RecoveryCallback.class), any(RetryState.class))).thenAnswer(invocation -> {
        RetryCallback retry = invocation.getArgument(0);
        return retry.doWithRetry(/*here goes RetryContext but it's ignored in ServiceRequest*/null);
    });
    when(restTemplate.exchange(anyString(), any(HttpMethod.class), any(HttpEntity.class), eq(String.class)))
            .thenReturn(myEntity);

    //when:
    ResponseEntity<String> response = serviceRequest.makeGetServiceCall(url);

    //then:
    assertEquals(myEntity, response);
}

我从方法调用 makeGetServiceCall 获得的响应对象始终返回 null。当我调试代码时，我在 resttemplate 上看到异常 org.mockito.exceptions.misusing.WrongTypeOfReturnValue: ResponseEntity cannot be returned by toString() toString() should return String 错误 mock 我返回 myEntity

我不确定我错过了什么。

Answer 1

嗯，你犯了很多错误......

1. 我确定您想用 @Mock 注释 private RetryTemplate retryTemplate;，而不是 @InjectMocks
2. @InjectMocks 应该转到 ServiceRequest serviceRequest;
3. 您正在一些与 serviceRequest 无关的 mockRetryTemplate 和 mockRestTemplate 上定义交互。相反，您应该使用带有 @Mock 注释的字段来定义交互，因为它们会被注入(inject)到您的测试对象中 (serviceRequest)
4. 此外，您通常无法模拟 RestTemplate 并将其注入(inject)到 ServiceRequest 中，因为您一开始就没有为 RestTemplate< 使用依赖项注入(inject)ServiceRequest 中的/code>。您只需在 ServiceRequest.makeGetServiceCall
中实例化其实例即可
5. 您在 Mockito.when(retryTemplate.execute(...) 行的错误方法上定义了交互。您的交互指定了 RetryTemplate.execute(RetryCallback, RecoveryCallback, RetryState) 而您的 ServiceRequest 使用另一种方法 RetryTemplate.execute(RetryCallback)
6. 您还应该注意到 RetryTemplate.execute 是最终的，因此您无法在没有额外努力的情况下模拟它，如所述 here 。一般来说，您应该更喜欢接口(interface)而不是类，例如RestOperations 和 RetryOperations 分别优于 RestTemplate 和 RetryTemplate，更加灵活。

也就是说，下面是解决您问题的工作测试。但请注意从 ServiceRequest 中删除 RestTemplate restTemplate = new RestTemplate(); 并将 restTemplate 设为一个字段，以便进行依赖注入(inject)。

@RunWith(MockitoJUnitRunner.class)
public class ServiceRequestTest {
    @Mock
    private RestTemplate restTemplate;

    @Mock
    public RequestConfig requestConfig;

    @Mock
    private RetryTemplate retryTemplate;

    @InjectMocks
    ServiceRequest serviceRequest;

    @Test
    public void makeGetServiceCall() throws Exception {
        //given:
        String url = "http://localhost:8080";
        ResponseEntity<String> myEntity = new ResponseEntity<>(HttpStatus.ACCEPTED);
        when(retryTemplate.execute(any(RetryCallback.class))).thenAnswer(invocation -> {
            RetryCallback retry = invocation.getArgument(0);
            return retry.doWithRetry(/*here goes RetryContext but it's ignored in ServiceRequest*/null);
        });
        when(restTemplate.exchange(eq(url), eq(HttpMethod.GET), any(HttpEntity.class), eq(String.class)))
                .thenReturn(myEntity);

        //when:
        ResponseEntity<String> response = serviceRequest.makeGetServiceCall(url);

        //then:
        assertEquals(myEntity, response);
    }
}