Null Pointer Exception on MockMvc.perform on #Test class - spring-boot

Question

I am writing to write a unit test for my RestController (POST) and I am getting a NullPointerException on mvc.perform(...) line.
Here's my RestController :
#RestController
#EnableAutoConfiguration
public class MyController {
#Autowired
private Service1 service;
#Autowired
RestTemplate restTemplate;
#RequestMapping(value = "/logError", method = RequestMethod.POST, produces = {MediaType.APPLICATION_JSON_VALUE})
#ResponseBody
public ResponseEntity ErrorHandlor(#RequestBody JSONStructure jsonStructure) throws Exception{
service.getDocument(jsonStructure.getID(), jsonStructure.getLog());
return new ResponseEntity(HttpStatus.OK);
}
}
And here is my test class:
#RunWith(SpringRunner.class)
#ContextConfiguration(classes = {MyController.class,
Service1.class, AppConfig.class})
#WebMvcTest(MyController.class)
public class MyControllerTest {
private MockMvc mockMvc;
#MockBean
private RestTemplate restTemplate;
MyController service = new MyController();
#Before
public void setUp() {
MockitoAnnotations.initMocks(this);
this.mockMvc = MockMvcBuilders.standaloneSetup(service).build();
}
#Test
public void testController() throws Exception{
ObjectMapper mapper = new ObjectMapper();
String url = "http://localhost:8080/logError";
JSONStructure structure = new JSONStructure();
structure.setNumber("num");
structure.setID("id");
structure.setLog("log");
String json = mapper.writeValueAsString(structure)
this.mockMvc.perform
(MockMvcRequestBuilders.post("http://localhost:8080/logError")
.contentType(MediaType.APPLICATION_JSON)
.content(json))
.andExpect(MockMvcResultMatchers.status().isCreated())
.andReturn();
}
}
I am getting a NPE on line containing this.mockMvc.perform(...).
Can anyone point out what might the problem be?

Answer 1

You will get it to work in this way (i tested it):
import static org.mockito.Mockito.when;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;
#SpringBootTest
public class TestControllerImplTest {
#Mock
private TestBO TestBO; //if for example the controller calls some autowired service
private MockMvc mockMvc;
#InjectMocks //i think this was your main problem, you missed this annotation
TestControllerImpl controller;
#BeforeEach
void setUp() throws Exception {
MockitoAnnotations.initMocks(this);
this.mockMvc = MockMvcBuilders.standaloneSetup(controller).build();
}
#Test()
void shouldReturnAllTests() throws Exception {
TestDTO testDTO = new TestDTO();
testDTO.setId(Long.valueOf(1));
List<TestDTO> allTests = new ArrayList(Arrays.asList(testDTO));
when(testBO.getAllTests()).thenReturn(allTests);
mockMvc.perform(get("/api/test/getAllTests")).andExpect(status().isOk()).andDo(print());
}
}

Answer 2

When using #RunWith(SpringRunner.class), use #Autowired MockMvc mockmvc.
When using #RunWith(MockitoJunitRunner.class) or MockitoAnnotations.initMocks(this) then
use this.mockMvc = MockMvcBuilders.standaloneSetup(service).build();
Don't mix both Spring and Mockito runners.