如何模拟调用 Rest API 的服务类并将 ResponseEntity 作为响应

Question

我有以下课程。

@Service
class RestService {
@Autowired
private RestTemplate restTemplate;

public ResponseEntity<String> callService(String param) {
return restTemplate.exchange(....);
}
}

---

@Service
class CallingService{
@Autowired
private RestService restService;

public ResponseDTO getResponse(String param) {
ResponseEntity<String> response = restService.callService(param);
ResponseDTO responseDTO = convert(response)// JSON Convertor here
return responseDTO;
}
}

---

现在我想为 CallingService 类编写测试类。

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertNull;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.mockito.Mockito.doNothing;
import static org.mockito.Mockito.doThrow;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;

import java.io.IOException;

import javax.xml.datatype.DatatypeConfigurationException;

import org.apache.cxf.helpers.IOUtils;
import org.junit.Before;
import org.junit.Rule;
import org.junit.jupiter.api.Test;
import org.junit.rules.ExpectedException;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.MockitoAnnotations;
import org.mockito.junit.MockitoJUnitRunner;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.core.env.Environment;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;

@RunWith(MockitoJUnitRunner.class)
@SpringBootTest
class CallingServiceTest{
@InjectMocks
private CallingService service;
@Mock
private RestService restService;

@Test
public testGetResponse(){
ResponseDTO dto = createDummyObject();

HttpHeaders header = new HttpHeaders();
header.setContentType(MediaType.APPLICATION_JSON);

ResponseEntity<String> responseEntity = new ResponseEntity<>("response message", header, 
HttpStatus.OK);

when(restService.callService(Mockito.anyString())).thenReturn(responseEntity);
// mocking converter here
 dto = service.getResponse("param");
//assert conditions here onwards
}
}

---

在 service.getResponse("param") 行的调用会产生 NullPointerException。在调试时，我发现在 CallingService.getResponse() 中收到的响应为 null（即 restService.callService(param) 返回 null），因此代码被分解为 convert() 方法。

我尝试了很多代码操作，但没有运气。希望任何人都可以回答这个问题。

Answer 1

您不能同时使用@RunWith(MockitoJUnitRunner.class) 和@SpringBootTest。他们都在设置 JUnit 规则，您只能激活一个规则。

你需要使用 Spring 注解。而不是 @Mock 使用 @MockBean 这样 Spring 可以正确地将其注入服务。

@SpringBootTest
class CallingServiceTest{
@Autowired
private CallingService service;
@MockBean
private RestService restService;

@Test
public testGetResponse(){
ResponseDTO dto = createDummyObject();

HttpHeaders header = new HttpHeaders();
header.setContentType(MediaType.APPLICATION_JSON);

ResponseEntity<String> responseEntity = new ResponseEntity<>("response message", header, 
HttpStatus.OK);

when(restService.callService(Mockito.anyString())).thenReturn(responseEntity);
// mocking converter here
 dto = service.getResponse("param");
//assert conditions here onwards
}
}

或者，您可以只使用 Mockito，因为我认为您实际上不需要为这个测试初始化​​ SpringContext。

@RunWith(MockitoJUnitRunner.class)
class CallingServiceTest{
@InjectMocks
private CallingService service;
@Mock
private RestService restService;

@Test
public testGetResponse(){
ResponseDTO dto = createDummyObject();

HttpHeaders header = new HttpHeaders();
header.setContentType(MediaType.APPLICATION_JSON);

ResponseEntity<String> responseEntity = new ResponseEntity<>("response message", header, 
HttpStatus.OK);

when(restService.callService(Mockito.anyString())).thenReturn(responseEntity);
// mocking converter here
 dto = service.getResponse("param");
//assert conditions here onwards
}
}

Answer 2

根据您的导入，您正在使用Junit4 和Junit5 的组合。 这将无法正常工作。

使用Junit5运行的步骤

1. 将您的导入更改为org.junit.jupiter.api.*
2. 将@Before 更改为@BeforeEach。
3. 删除 @SpringBootTest 不需要 Junit5
4. 将@RunWith(MockitoJUnitRunner.class) 更改为@ExtendWith(MockitoExtension.class)

请在下面找到更改后的代码

@ExtendWith(MockitoExtension.class)
class CallingServiceTest{
@InjectMocks
private CallingService service;
@Mock
private RestService restService;

@Test
public testGetResponse(){
ResponseDTO dto = createDummyObject();

HttpHeaders header = new HttpHeaders();
header.setContentType(MediaType.APPLICATION_JSON);

ResponseEntity<String> responseEntity = new ResponseEntity<>("response message", header, 
HttpStatus.OK);

when(restService.callService(Mockito.anyString())).thenReturn(responseEntity);
// mocking converter here
 dto = service.getResponse("param");
//assert conditions here onwards
}
}

如果您想使用Junit4 运行，请将@Test 的导入从import org.junit.jupiter.api.Test 更改为import org.junit.Test

任何一种解决方案都可以。

Answer 3

我终于通过结合上述两个答案的风格找到了解决方法。

import static org.junit.Assert.*;
import static org.mockito.Mockito.*;

import org.apache.cxf.helpers.IOUtils;
import org.junit.Before;
import org.junit.Rule;
import org.junit.
import org.junit.Test;
import org.junit.jupiter.api.BeforeEach;
import org.junit.rules.ExpectedException;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.MockitoAnnotations;
import org.mockito.junit.MockitoJUnitRunner;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.core.env.Environment;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;

@RunWith(MockitoJUnitRunner.class)
@SpringBootTest
public class CallingServiceTest{
@InjectMocks
private CallingService service;
@Mock
private RestService restService;
@BeforeEach
public void setup(){
MockitoAnnotations.init(this);
}

@Test
public testGetResponse(){
ResponseDTO dto = createDummyObject();

HttpHeaders header = new HttpHeaders();
header.setContentType(MediaType.APPLICATION_JSON);

ResponseEntity<String> responseEntity = new ResponseEntity<>   ("response message", header, HttpStatus.OK);

     when(restService.callService(Mockito.anyString())).thenReturn(responseEntity);
// mocking converter here
dto = service.getResponse("param");
//assert conditions here onwards
}
}