How to Mock with MockHttpSession and Junit - spring

Question

Looked at this post where #slim gave a solution close to what I am asking about. I am trying to write unit test on the class below. I am pulling out the sessionId. (look for String sessId inside doFilterInternal method)
#Component
public class AppLoggingFilter extends OncePerRequestFilter {
private AppLoggingMDCService mdcService;
#Inject
public AppLoggingFilter(AppLoggingMDCService appLoggingMDCService) {
Assert.notNull(appLoggingMDCService, "AppLoggingMDCService must not be null");
this.mdcService = appLoggingMDCService;
}
#Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
Principal principal = request.getUserPrincipal();
String sessId = DigestUtils.sha256Hex(request.getSession().getId());
if (principal != null) {
String userId = principal.getName();
mdcService.put(AppLoggingMDCService.LOG_KEY_USER_ID, userId);
}
mdcService.put(AppLoggingMDCService.LOG_KEY_SESSION_ID, sessId);
try {
filterChain.doFilter(request, response);
} finally {
mdcService.removeAll();
}
}
Naturally the test below is failing because I don't have a valid session. Obviously I am getting a null-pointer-exception whenever i call filter.doFilterInternal(request, response, filterChain);. In the test class, the "mock-session" is not set up and has no ID. In my unit test I have this.
#RunWith(SpringJUnit4ClassRunner.class)
#ActiveProfiles(value = {"test"})
public class AppLoggingFilterUnitTest {
#Mock
AppLoggingMDCService mdcService;
#Mock
MockHttpServletRequest request;
#Mock
MockHttpServletResponse response;
#Mock
MockFilterChain filterChain;
#Mock
MockHttpSession session;
#InjectMocks
AppLoggingFilter filter;
#Before
public void setUp() {
MockitoAnnotations.initMocks(this);
request.setSession(session);
}
#Test
public void testCustomerIdHasBeenLogged() throws Exception {
String customerId = "1234";
when(request.getHeader(AuthorizationConstants.CUSTOMER_KEY)).thenReturn(customerId);
filter.doFilterInternal(request, response, filterChain);
verify(mdcService, times(1)).put(AppLoggingMDCService.LOG_KEY_CUST_ID,customerId);
}
}
So coming back to my question, how do simulate as valid mocked "MockHttpSession" so my others tests don't fail?
UPDATE
So I added the session into my test class like this. In my setup method is where I said to return the "Mocked" session. The test passes only when I call
String sessId = request.getSession().getId();. if I try to do the DigestUtils.sha256Hex like
String sessId = DigestUtils.sha256Hex(request.getSession().getId()); ,all tests fail due to a null-pointer. I am not sure why. Mocking DigestUtils doesn't make much sense.
#Mock
AppLoggingMDCService mdcService;
#Mock
HttpServletRequest request;
#Mock
HttpServletResponse response;
#Mock
FilterChain filterChain;
#Mock
HttpSession session;
#InjectMocks
AppLoggingFilter filter;
#Before
public void setUp() {
MockitoAnnotations.initMocks(this);
when(request.getSession()).thenReturn(this.session);
}

Answer 1

You are doing to much in your test and it is way to complex. Remove the runner, remove Mockito for the Mock* as those need to be instantiated not mocked.
public class AppLoggingFilterUnitTest {
#Mock
private AppLoggingMDCService mdcService;
#InjectMocks
private AppLoggingFilter filter;
private MockHttpServletRequest request;
private MockHttpServletResponse response = new MockHttpServletResponse();
private MockFilterChain filterChain = new MockFilterChain();
#Before
public void setUp() {
MockitoAnnotations.initMocks(this);
this.request = new MockHttpServletRequest();
this.request.addHeader(AuthorizationConstants.CUSTOMER_KEY, "1234");
}
#Test
public void testCustomerIdHasBeenLogged() throws Exception {
filter.doFilterInternal(request, response, filterChain);
verify(mdcService, times(1)).put(AppLoggingMDCService.LOG_KEY_CUST_ID,customerId);
}
}
With the creating of the mocks for the Mock* classes you basically defeated the purpose of those classes.