JUnit:无法模拟RestTemplate对象调用postForObject方法

Question

我对Mockito和Spring的RestTemplate都是新手。我正在为一个功能进行JUnit测试，该功能向web服务发送请求并通过使用RestTemplate获得响应。我希望服务器响应我想要的响应，以便我可以测试基于此响应的功能。我用Mockito来嘲讽。

我不确定我哪里错了。我没有创建合适的mock吗?我的JSON对象映射器没有正确配置吗?

定义RestTemplate bean的配置文件:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
        <bean id="restTemplate" class="org.springframework.web.client.RestTemplate">
        <property name="messageConverters">
            <list>
                <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter" />
                <bean class="org.springframework.http.converter.xml.SourceHttpMessageConverter"/>
                <bean class="org.springframework.http.converter.xml.MarshallingHttpMessageConverter">
                    <property name="marshaller"  ref="xsStreamMarshaller" />
                    <property name="unmarshaller" ref="xsStreamMarshaller" />
                </bean>
            </list>
        </property>
    </bean>    
    <bean id="xsStreamMarshaller" class="org.springframework.oxm.xstream.XStreamMarshaller"></bean>
</beans>

我的DTO的

:

import org.codehaus.jackson.annotate.JsonWriteNullProperties;
@JsonWriteNullProperties(false)
public abstract class BaseDTO {
    protected boolean error;
    public boolean isError() {
        return error;
    }
    public void setError(boolean error) {
        this.error = error;
    }
}
public class ChildDTO extends CommercialBaseDTO {   
    private String fullName;    
    public String getFullName() {
        return fullName;
    }
    public void setFullName(String fullName) {
        this.fullName = fullName;
    }
}

包含测试方法的类:

package com.exmpale.mypackage;  
import org.springframework.web.client.RestTemplate;
@Component
public class MyUtilClass {
    @Autowired
    private RestTemplate restTemplate;
    public RestTemplate getRestTemplate(){
        return restTemplate;
    }
    public void setRestTemplate(RestTemplate restTemplate){
        this.restTemplate = restTemplate;
    }
    // Method to test       
    public ChildDTO getChildDTO(MyUser myUser, HttpServletRequest request, HttpServletResponse response)
    {
        response.setContentType("application/json");        
        //Nothing much here, it takes the myUser and convert into childDTO  
        ChildDTO childDTO = new MyUtilClass().getDTOFromUser(request, myUser);  
        //This is the restTemplate that iam trying to mock.
        childDTO = restTemplate.postForObject("http://www.google.com", childDTO, ChildDTO.class);
        if (childDTO.isError()) {
            //Then do some stuff.........           
        }
        return childDTO;
    }
}

JUnit测试类

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations={"test-config.xml"})
public class MyUtilClassTest {
    @InjectMocks
    RestTemplate restTemplate= new RestTemplate();
    private MockRestServiceServer mockServer;
    @Before
    public void setUp() throws Exception {
        MockitoAnnotations.initMocks(this);
        //Creating the mock server      
        //Add message conveters
        List<HttpMessageConverter<?>> messageConverters = new ArrayList<HttpMessageConverter<?>>();
        messageConverters.add(new FormHttpMessageConverter());
        messageConverters.add(new StringHttpMessageConverter());
        messageConverters.add(new MappingJacksonHttpMessageConverter());
        //Create Object mapper
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.configure( DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        objectMapper.configure( SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS, false);
        objectMapper.configure( SerializationConfig.Feature.AUTO_DETECT_FIELDS, true);
        objectMapper.configure( SerializationConfig.Feature.AUTO_DETECT_GETTERS,true);
        objectMapper.configure( SerializationConfig.Feature.AUTO_DETECT_IS_GETTERS,true);
        MappingJacksonHttpMessageConverter jsonMessageConverter = new MappingJacksonHttpMessageConverter();
        jsonMessageConverter.setObjectMapper(objectMapper);
        messageConverters.add(jsonMessageConverter);
        //Set the message converters 
        restTemplate.setMessageConverters(messageConverters);        
        mockServer = MockRestServiceServer.createServer(restTemplate);
    }
    @Test
    public void testGetChildDTO()throws Exception {
        MyUtilClass myUtil = new MyUtilClass();         
        MyUser myUser = new MyUser();
        HttpServletRequest request = new HttpServletRequestWrapper(new MockHttpServletRequest());
        HttpServletResponse response = new HttpServletResponseWrapper(new MockHttpServletResponse());       
        //create the mocks for ChildDTO. I want MyUtilClass().getDTOFromUser(request, myUser) to return this.
        ChildDTO childDTOMock_One =  Mockito.mock(ChildDTO);            
        //Want this to be returned when restTemplate.postForObject() is called.
        ChildDTO childDTOMock_Two =  Mockito.mock(ChildDTO.class);
        childDTOMock_Two.setError(false);
        //create the mocks for userMgntUtils
        MyUtilClass myUtilClassMock =  Mockito.mock(MyUtilClass.class);     
        //stub the method getDTOFromUser() to return the mock object. I need this mock to be passed to 'postForObject()'
        Mockito.when(myUtilClassMock.getDTOFromUser(request, myUser)).thenReturn(childDTOMock_One);
        String responseJSON="{"error":false}";
        //set the expectation values for mockServer
        mockServer.expect( requestTo("http://www.google.com")).andExpect(method(HttpMethod.POST)).andRespond(withSuccess(responseJSON,MediaType.APPLICATION_JSON));
        //set the expectation values for restTemplate
        Mockito.when(restTemplate.postForObject( "http://www.google.com", childDTOMock_One, ChildDTO.class)).thenReturn(childDTOMock_Two);
        TypedUserDTO result = userMgmtUtils.getUserProfileDTO(registerUser, request, response, action);
        assertNotNull(result);
    }
}

得到以下异常:

org.springframework.http.converter.HttpMessageNotWritableException:无法写JSON:没有找到类的序列化器org.mockito.internal.stubbing.defaultanswers.GloballyConfiguredAnswer并且没有发现创建BeanSerializer(要避免)的属性异常，禁用SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS))(通过参考链:com.biogenidec.dto.TypedUserDTO EnhancerByMockitoWithCGLIB美元bee3c447美元("回调")——> org.mockito.internal.creation.MethodInterceptorFilter("处理器")——> org.mockito.internal.handler.InvocationNotifierHandler("mockSettings")——> org.mockito.internal.creation.settings.CreationSettings [" defaultAnswer "]);嵌套异常是org.codehaus.jackson.map.JsonMappingException: No为类找到序列化器org.mockito.internal.stubbing.defaultanswers.GloballyConfiguredAnswer并且没有发现创建BeanSerializer(要避免)的属性异常，禁用SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS))(通过参考链:com.biogenidec.dto.TypedUserDTO EnhancerByMockitoWithCGLIB美元bee3c447美元("回调")——> org.mockito.internal.creation.MethodInterceptorFilter("处理器")——> org.mockito.internal.handler.InvocationNotifierHandler("mockSettings")——> org.mockito.internal.creation.settings.CreationSettings [" defaultAnswer "])

和

:

Caused by: org.codehaus.jackson.map.JsonMappingException: No serializer found for class org.mockito.internal.stubbing.defaultanswers.GloballyConfiguredAnswer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: com.biogenidec.dto.TypedUserDTO$$EnhancerByMockitoWithCGLIB$$bee3c447["callbacks"]->org.mockito.internal.creation.MethodInterceptorFilter["handler"]->org.mockito.internal.handler.InvocationNotifierHandler["mockSettings"]->org.mockito.internal.creation.settings.CreationSettings["defaultAnswer"])

Answer 1

Mockito的想法是测试类，而不是它之外的依赖项。因此，如果您测试MyUtilClass，您希望模拟RestTemplate类。你的@InjectMocks在错误的类上，见下文。

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations={"test-config.xml"})
public class MyUtilClassTest 
{
    @Mock
    private RestTemplate restTemplate;
    @InjectMocks
    private MyUtilClass myUtilClass;
    @Before
    public void setUp() throws Exception 
    {
        MockitoAnnotations.initMocks(this);
    }
    @Test
    public void testGetChildDTO()throws Exception 
    {
         MyUser myUser = new MyUser();
         HttpServletRequest request = new HttpServletRequestWrapper(new MockHttpServletRequest());
         HttpServletResponse response = new HttpServletResponseWrapper(new MockHttpServletResponse());    
         Mockito.when(RestTemplate.postForObject(Mockito.eq("http://www.google.com", 
            Mockito.any(ChildDTO.class), Mockito.eq(ChildDTO.class)))).thenAnswer(
            new Answer<ChildDTO>()
            {
                @Override
                public ChildDTO answer(InvocationOnMock invocation) throws Throwable
                {
                     //The below statement takes the second argument passed into the method and returns it
                    return (ChildDTO) invocation.getArguments()[1];
                }
            });
         ChildDTO childDTO = myUtilClass.getDTOFromUser(request, myUser);
         //then verify that the restTemplate.postForObject mock was called with the correct parameters
         Mockito.verify(restTemplate, Mockito.times(1)).postForObject(Mockito.eq("http://www.google.com",
            Mockito.eq(childDTO), Mockito.eq(ChildDTO.class));
    }
 }

我也发现测试其他框架的类是不好的做法，更多的时候他们已经测试了他们的类，而你只是在重复他们的工作。

Answer 2

正如上面正确指出的，要用mockit测试您的方法，不需要初始化restTemplate。验证输入的参数是否正确(如果需要的话)并从restTemplate返回正确的mock对象就足够了。

这里不测试restTemplate，只测试代码。这就是单元测试的目的。

你可以这样做，或者更简单:

@RunWith(value = MockitoJUnitRunner.class)
public class Test {
@InjectMocks
private MyUtilClass testObj;
@Mock
private RestTemplate restTemplate;
@Mock
MyUser myUser;
@Mock
HttpServletRequest request;
@Mock
HttpServletResponse response;
@Test
public void test() throws Exception {
        //Configure sample to comparison and verification the result of the method:
        ChildDTO sample = getSample();
        //configure mocks:
        ChildDTO myObject = new ChildDTO();
        //configure myObject properties
        ResponseEntity<ChildDTO> respEntity = new ResponseEntity<>(
                myObject, HttpStatus.ACCEPTED);
        when(restTemplate.postForObject(anyString(), Matchers.<HttpEntity<?>>any(),
                Matchers.any(Class.class))).thenReturn(respEntity);
        //other stuff to configure correct behaviour of mocks request, response e.t.c.
        //act:
        ChildDTO result = testObj.getChildDTO(myUser, request, response);
        //verify that correct parameters were passed into restTemplate method "postForObject":
        verify(restTemplate).postForObject(eq("http://www.google.com"), Matchers.<HttpEntity<?>>any(),
                eq(ChildDTO.class)).thenReturn(respEntity);
        //assert to verify that we got correct result:
        assertEquals(sample, result);
    }    
}