Spring Boot Unit Testing MockMvc Null Body - spring-boot

Question

I am having dificulties with using MockMvc.
Here I have simple Service and controller classes:
Service:
#Slf4j
#Service
public class EmployeeService {
//...
public Employee GetSample() {
//...
//filling Employee Entities
return new Employee(
"Harriet"
, "random"
, 25);
}
}
controller:
#RestController
#RequestMapping(value = "/info")
#RequiredArgsConstructor(onConstructor = #__(#Autowired))
#Validated
public class EmployeeController {
private final EmployeeService employeeService;
#PostMapping("/GetEmployee")
public ResponseEntity<Employee> GetEmployee() {
Employee employee = employeeService.GetSample();
return new ResponseEntity<>(employee, HttpStatus.OK);
}
}
Test:
#RunWith(SpringJUnit4ClassRunner.class)
#SpringBootTest
public class EmployeeTestCase {
private MockMvc mockMvc;
#InjectMocks
private EmployeeController EmployeeController;
#Mock
private EmployeeService employeeService;
#Before
public void setUp() {
this.mockMvc = MockMvcBuilders.standaloneSetup(employeeController).build();
}
#Test
public void getEmployee() throws Exception {
this.mockMvc.perform(MockMvcRequestBuilders.post("/info/GetEmployee")).andDo(print());
}
}
when I try to use MockMvc I get null body. It seems employee is null. But I didn't understand why.
I thought that when test uses perform, it should initialise employee and later on it should't be null.
I tried to cut the code as much as possible. I hope it is not long.
Note : also tried to use Mockito.when(employeeController.GetEmployee()).thenCallRealMethod();

Answer 1

The #SpringBootTest annotation loads the complete Spring application
context. That means you do not mock your layers
(Services/Controllers).
If you wanted to test specific layers of your application, you could look into test slice annotations offered by Springboot: https://docs.spring.io/spring-boot/docs/current/reference/html/test-auto-configuration.html
In contrast, a test slice annotation only loads beans required to test a particular layer. And because of this, we can avoid unnecessary mocking and side effects.
An example of a Test Slice is #WebMvcTest
#ExtendWith(SpringExtension.class)
#WebMvcTest(controllers = HelloController.class,
excludeFilters = {
#ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE, classes = SecurityConfig.class)
}
)
public class HelloControllerTest {
#Autowired
private MockMvc mvc;
#Test
public void hello() throws Exception {
String hello = "hello";
mvc.perform(get("/hello"))
.andExpect(status().isOk())
.andExpect(content().string(hello));
}
#Test
public void helloDto() throws Exception {
String name = "hello";
int amount = 1000;
mvc.perform(
get("/hello/dto")
.param("name", name)
.param("amount", String.valueOf(amount)))
.andExpect(status().isOk())
.andExpect(jsonPath("$.name", is(name)))
.andExpect(jsonPath("$.amount", is(amount)));
}
}
However if you really wanted to load up the SpringBoot Application context, say for an Integration Test, then you have a few options:
#SpringBootTest
#AutoConfigureMockMvc
public class TestingWebApplicationTest {
#Autowired
private MockMvc mockMvc;
#Test
public void shouldReturnDefaultMessage() throws Exception {
this.mockMvc.perform(get("/")).andDo(print()).andExpect(status().isOk())
.andExpect(content().string(containsString("Hello, World")));
}
}
#RunWith(SpringJUnit4ClassRunner.class)
#SpringBootTest
public class AuctionControllerIntTest {
#Autowired
AuctionController controller;
#Autowired
ObjectMapper mapper;
MockMvc mockMvc;
#Before
public void setUp() throws Exception {
System.out.println("setup()...");
mockMvc = MockMvcBuilders.standaloneSetup(controller).build();
}
#Test
public void create_ValidAuction_ShouldAddNewAuction() throws Exception {
final Auction auction = new Auction(
"Standing Desk",
"Stand up desk to help you stretch your legs during the day.",
"Johnnie34",
350.00);
mockMvc.perform(post("/auctions")
.contentType(MediaType.APPLICATION_JSON)
.content(toJson(auction)))
.andExpect(status().isCreated());
}
}
Lets say you don't want to load up any layers at all, and you want to mock everything, such as for example a Unit Test:
#RunWith(MockitoJUnitRunner.class)
class DemoApplicationTest {
#Mock
private UserRepository userRepository;
private Demo noneAutoWiredDemoInstance;
#Test
public void testConstructorCreation() {
MockitoAnnotations.initMocks(this);
Mockito.when(userRepository.count()).thenReturn(0L);
noneAutoWiredDemoInstance = new Demo(userRepository);
Assertions.assertEquals("Count: 0", noneAutoWiredDemoInstance.toString());
}
}