How to unit testing spring boot rest controller and exception handler using power mock

Question

I am having a simple Spring boot application which contains Employee controller which returns the Employee names if the year passed is greater than 2014 and if the it is not less than 2014 then I am throwing a custom exception and handling it in Exception Handler.
I want to unit test the exception flow using powermock but I am not sure how to do it. I have gone through some links but unable to understand.
Currently I am getting java.lang.IllegalArgumentException: WebApplicationContext is required.

EmployeeController.java

@RestController
public class EmployeeController{

    @GetMapping(value = "/employee/{joiningYear}",produces = MediaType.APPLICATION_JSON_VALUE)
    public List<String> getEmployeeById(@PathVariable int joiningYear) throws YearViolationException {

        if(joiningYear < 2014){
            throw new YearViolationException("year should not be less than 2014");
        }else{

            // send all employee's names joined in that year 
        }
        return null;
    }
}   

ExceptionHandler

@RestControllerAdvice
public class GlobalControllerExceptionHandler {


    @ExceptionHandler(value = { YearViolationException.class })
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    public ApiErrorResponse yearConstraintViolationExceptio(YearViolationException ex) {

        return new ApiErrorResponse(400, 5001, ex.getMessage());
    }
}

CustomException

public class YearViolationException extends Exception {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    public YearViolationException(String message) {

        super(message);
    }

}

Junit to unit test exception handler

@RunWith(PowerMockRunner.class)
@WebAppConfiguration
@SpringBootTest
public class ExceptionControllerTest {

    @Autowired
    private WebApplicationContext applicationContext;

    private MockMvc mockMVC;

    @Before
    public void setUp() {

        mockMVC = MockMvcBuilders.webAppContextSetup(applicationContext).build();
    }

    @Test
    public void testhandleBanNotNumericException() throws Exception {

        mockMVC.perform(get("/employee/2010").accept(MediaType.APPLICATION_JSON)).andDo(print())
                .andExpect(status().isBadRequest())
        .andExpect(content().contentTypeCompatibleWith(MediaType.APPLICATION_JSON));

    }
}

Answer 1

As stated by others, you don't need mockMVC at all. If you want to test REST endpoints, what you need is TestRestTemplate. Runwith SpringRunner.class is important as well as the WebEnvironment setup.

@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment=WebEnvironment.RANDOM_PORT)
public class RestServiceApplicationTests {

    private String baseUrl = "http://localhost:8090";

    private String endpointToThrowException = "/employee/2010";

    @Autowired
    private TestRestTemplate testRestTemplate;

    @Test(expected = YearViolationException.class)
    public void testhandleBanNotNumericException() {
        testRestTemplate.getForObject(baseUrl + endpointToThrowException, String.class);
}