junit - 如何使用 mockito 模拟 ObjectMapper.readValue()

Question

我正在测试服务层，但不确定如何模拟 ObjectMapper().readValue在那个类(class)。我对 mockito 还很陌生并且可以弄清楚该怎么做。

以下是我的代码，

服务.java

private configDetail fetchConfigDetail(String configId) throws IOException {
    final String response = restTemplate.getForObject(config.getUrl(), String.class);
    return new ObjectMapper().readValue(response, ConfigDetail.class);
}

服务测试.java

@Test
public void testgetConfigDetailReturnsNull() throws Exception {

    restTemplate = Mockito.mock(restTemplate.class);
    Service service = new Service();
    Config config = Mockito.mock(Config.class);
    ObjectMapper objMapper = Mockito.mock(ObjectMapper.class);
            Mockito.doReturn("").when(restTemplate).getForObject(anyString(), eq(String.class));
    Mockito.doReturn(configDetail).when(objMapper).readValue(anyString(),eq(ConfigDetail.class));
    assertEquals(configDetail, service.getConfigDetail("1234"));
}

运行此测试时，我得到以下结果，

com.fasterxml.jackson.databind.exc.MismatchedInputException: No content to map due to end-of-input
 at [Source: (String)""; line: 1, column: 0]

在此处发布 ServiceTest.Java

@RunWith(MockitoJUnitRunner.class)
public class ConfigServiceTest {

    @Mock
    private ConfigPersistenceService persistenceService;

    @InjectMocks
    private ConfigService configService;

    @Mock
    ConfigDetail configDetail;

    @Mock
    private RestTemplate restTemplate;

    @Mock
    private ObjectMapper objMapper;

    @Mock
    private Config config;

    @Test
    public void testgetConfigDetailReturnsNull() throws Exception {

        ObjectMapper objMapper = Mockito.mock(ObjectMapper.class);
        Mockito.doReturn(ucpConfig).when(persistenceService).findById("1234");

        Mockito.doReturn("").when(restTemplate).getForObject(anyString(), eq(String.class));

        Mockito.when((objMapper).readValue(“”,ConfigDetail.class)).thenReturn(configDetail);
        assertEquals(ConfigDetail, ConfigService.getConfigDetail("1234"));
    }
}

Answer 1

使用您当前的 Service 类将很难模拟 ObjectMapper , ObjectMapper与 fetchConfigDetail 紧密耦合方法。

你必须改变你的服务类如下模拟 ObjectMapper .

@Service
public class MyServiceImpl {

    @Autowired
    private ObjectMapper objectMapper;

    private configDetail fetchConfigDetail(String configId) throws IOException {
        final String response = restTemplate.getForObject(config.getUrl(), String.class);
        return objectMapper.readValue(response, ConfigDetail.class);
    }
}

我在这里所做的不是创建 objectMapper在我从外部注入(inject)的方法内部(在这种情况下， objectMapper 将由 Spring 创建)

更改服务类别后，您可以模拟 objectMapper如下。

ObjectMapper mockObjectMapper = Mockito.mock(ObjectMapper.class);
Mockito.when(mockObjectMapper.readValue(anyString(), any(ConfigDetail.class)).thenReturn(configDetail);