Null Body in SpringBoot WebMvcTest - junit

Question

I am getting a result from my unit test that I don't quite understand.
Controller Code
package com.rk.capstone.controllers;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import com.rk.capstone.model.domain.User;
import com.rk.capstone.model.services.user.IUserService;
/**
* REST Controller for /register endpoint
*/
#RestController
#RequestMapping("/register")
public class RegisterController {
private final IUserService userService;
public RegisterController(IUserService userService) {
this.userService = userService;
}
#RequestMapping(value = "/user", method = RequestMethod.POST)
public ResponseEntity<User> registerNewUser(#RequestBody User user) {
if (userService.findByUserName(user.getUserName()) == null) {
user = userService.saveUser(user);
return ResponseEntity.status(HttpStatus.CREATED).body(user);
} else {
return ResponseEntity.status(HttpStatus.CONFLICT).body(null);
}
}
}
Unit Test Code:
package com.rk.capstone.controllers;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.web.servlet.MockMvc;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.rk.capstone.model.dao.UserDao;
import com.rk.capstone.model.domain.User;
import com.rk.capstone.model.services.user.IUserService;
import static org.mockito.BDDMockito.given;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
/**
* Class Provides Unit Testing for RegisterController
*/
#RunWith(SpringRunner.class)
#WebMvcTest(RegisterController.class)
public class RegisterControllerTest {
#MockBean
private IUserService userService;
#Autowired
private MockMvc mockMvc;
private User user;
private String userJson;
#Before
public void setup() {
user = new User("rick", "k", "rick#email.com", "rkow", "abc123");
ObjectMapper objectMapper = new ObjectMapper();
try {
userJson = objectMapper.writeValueAsString(user);
} catch (JsonProcessingException e) {
e.printStackTrace();
}
}
#Test
public void testRegisterNewUserPostResponse() throws Exception {
given(this.userService.findByUserName(user.getUserName())).willReturn(null);
given(this.userService.saveUser(user)).willReturn(user);
Assert.assertNotNull("Mocked UserService is Null", this.userService);
this.mockMvc.perform(post("/register/user").content(userJson).
contentType(MediaType.APPLICATION_JSON)).
andExpect(status().isCreated()).
andDo(print()).andReturn();
}
}
The result of the print() is below, I do not understand why the Body is empty. I have tried numerous things I've read on other posts and blogs and no matter what I try the Body is always empty. Adding a Content-Type header in the controller response makes no difference.
MockHttpServletResponse:
Status = 201
Error message = null
Headers = {}
Content type = null
Body =
Forwarded URL = null
Redirected URL = null
Cookies = []
What is confounding me even more, is when I run the actual application and perform a POST using PostMan to the /register/user endpoint the response contains the body and status code I expect, a User represented via JSON, e.g.
Status Code: 201 Created
Response Body
{
"userId": 1,
"firstName": "rick",
"lastName": "k",
"emailAddress": "rick#email.com",
"userName": "rk",
"password": "abc123"
}
Any help or ideas is appreciated, using SpringBoot 1.4.0.RELEASE.
UPDATE: For some reason the following mocked method call is returning null in the controller under test.
given(this.userService.saveUser(user)).willReturn(user);

Answer 1

This thread ultimately turned me on to a solution:
Mockito when/then not returning expected value
Changed this line:
given(this.userService.saveUser(user)).willReturn(user);
to
given(this.userService.saveUser(any(User.class))).willReturn(user);