Spring Security and MockMvc - Need to mock authentication or principal - spring

Question

I'm using Spring Security, and facing issue writing unit test case (using MockMvc) for a controller.
I have a method in my controller that goes something like this:
#GetMapping
public ResponseEntity<User> getUser(#AuthenticationPrincipal User activeUser){
String userEmail = activeUser.getEmail();
return userService.getUser(userEmail);
}
I get a 500 error with this.
Another variation for the controller I've tried is, and this is working on Postman/Curl :
#GetMapping
public ResponseEntity<User> getUser(OAuth2Authentication authentication){
String userEmail = (String) authentication.getUserAuthentication().getPrincipal();
return userService.getUser(userEmail);
}
My service looks like :
public ResponseEntity<User> getUser(String email) {
return userRepository.findByEmail(email)
.map(record -> ResponseEntity.ok().body(record))
.orElse(ResponseEntity.notFound().build());
}
In my unit test case for this controller method, I have:
#Test
#WithMockUser(username = "1", password = "pwd", roles = "USER")
public void controller_should_get_user() throws Exception {
when(userService.getUser("1")).thenReturn(new ResponseEntity(userMock, HttpStatus.OK));
this.mockMvc.perform(MockMvcRequestBuilders.get("/api/user/")).andExpect(status().isOk());
}
I am getting the following error:
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
at com.timecloud.user.controller.UserControllerTest.controller_should_get_user(UserControllerTest.java:60)
How should I go about passing or mocking a user with the current authentication? Thanks.

Answer 1

#WithMockUser creates a UsernameAuthenticationToken, not an OAuth2Authentication.
At least three solutions here:
Inject an OAuth2Authentication mock or instance in the security context
change your method to public ResponseEntity<User> getUser(Authentication authentication), then using authentication.getName() inside
use some existing tooling to apply solution 1. for you, like in this libs I wrote
Sample usage with solution 1
#Test
public void test() throws Exception {
final var storedRequest = mock(OAuth2Request);
final var principal = mock(Principal.class);
when(principal.getName()).thenReturn("user");
final var userAuthentication = mock(Authentication.class);
when(userAuthentication.getAuthorities()).thenReturn(Set.of(new SimpleGrantedAuthority("ROLE_USER"));
when(userAuthentication.getPrincipal()).thenReturn(principal);
final var oauth2Authentication = new OAuth2Authentication(storedRequest, authentication);
SecurityContextHolder.getContext().setAuthentication(oauth2Authentication);
// use MockMvc to test a #Controller or unit-test any other secured #Component as usual
}
Sample usage with solution 3
#Test
#WithMockAuthentication(authType = OAuth2Authentication.class, name = "user", authorities = "ROLE_USER")
public void test() throws Exception {
// use MockMvc to test a #Controller or unit-test any other secured #Component as usual
}

Answer 2

NullPointerException is coming because your test is unable to find anything for OAuth2Authentication Object. There are two things you can do your test case:
Try Mocking OAuth2Authentication in some setUp method.
OR
If you are using Spring 4.0+, the best solution is to annotate the test method with #WithMockUser
#Test
#WithMockUser(username = "user1", password = "pwd", roles = "USER")
public void mytest1() throws Exception {
//Your test scenario
}