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Getting NullPointerException when run unit test using Spring boots, JUnit 5 and Mockito

Posts: 7
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I am new Spring boots, JUnit 5 and Mockito.
I am trying to learn this technolgy.
I have simple RestController with one method createUser.
When I test this controller method through Postman, it work fine.
But when run unit test (Shown below), I am getting NullPointerException (marked inside method).
It is not creating userResponse. Here is the code;

Please can someone advice me where I am going wrong.

public class UserRestController {

UserService userService;

@PostMapping(path="save", consumes= {MediaType.APPLICATION_JSON_VALUE}, produces= {MediaType.APPLICATION_JSON_VALUE})
public String createUser(@RequestBody User user) {
User userResponse = userService.createUser(user);
System.out.println("userResponse ..: " + userResponse );  // These is null when Test run

return String.valueOf(userResponse.getId());
} //  end UserController

public class UserServiceImpl implements UserService {

private UserRepository userRepository;

public User createUser(User user) {
User userResponse = userRepository.save(user);
return userResponse;

public class UserRestControllerTest {

private MockMvc mockMvc;

private ObjectMapper objectMapper;

UserService userService;

@DisplayName("UserRestController createUser Test")
public void createUserTest() throws JsonProcessingException, Exception {

User newUser = new User("Mr", "Dabby", "Wall", 27);
User savedUser = new User(1, "Mr", "Dabby", "Wall", 27);


String url = "/user/save";

Here is error I am getting;
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1014)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:652)
Caused by: java.lang.NullPointerException
at com.ics.restController.UserRestController.createUser(UserRestController.java:37)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

Posts: 2037
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Hi, Ish,
Try to annotate @AutoConfigureMvc to your WebMvcTest class. I guess your MockMvc is null.
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