NullPointException in Unit tests what to do?

Question

Java

@ExtendWith(MockitoExtension.class)
@RunWith(JUnitPlatform.class)
class UserControllerTest {
@InjectMocks
UserController userController;
@Mock
UserDao userDao;
@Test
public void testGetAllUsers() throws Exception {
// given
User user1= new User(UUID.fromString("2bf303c7-9999-4e3c-a14d-457251cb4d8d"), "Vasya Petrov", "[phone]");
User user2= new User(UUID.fromString("2bf303c7-1111-4e3c-a14d-457251cb4d8d"), "Vera Sidorova", "[phone]");
List users = new ArrayList<>();
users.add(user1);
users.add(user2);
when(userDao.
// when
List result = userController.getAllUsers();
// then
assertThat( result.size()).isEqualTo(2);
}
Crashes on NullPointException don't know how to solve it

Answer 1

In the stacktrace, you can see the entire chain of calls leading to the NPE, and understand for which call you forgot to describe the behavior of the mock.