My Junit test has given java.lang.NullPointerException

This is the test class, It runs pretty well initially but after fixing some bugs from javax validation it started giving error

**Actually I am new to JUnit testing and am very confused with this error I am getting. The error, Null Pointer exception. Please I will appreciate I some can lead me to solution **

    @RunWith(SpringJUnit4ClassRunner.class)
    @SpringBootTest
    class NhSystemApplicationTests {

        @Autowired
        private UserService userService;

        @Autowired
        private TaskService taskService;

    @Before(value = "")
    public void initDb() {
        {
        User newUser = new User("testUser@mail.com", "testUser", "****");
        userService.createUser(newUser);
        }

        {
        User newUser = new User("testAdmin@mail.com", "testUser", "*****");
        userService.createUser(newUser);
        }

        Task userTask = new Task("02/01/2018", "00:11", "11:00", "You need to work Today");
        User user = userService.findOne("testUser@mail.com");
        taskService.addTask(userTask, user);  
    }

    @Test
    public void testUser() {

        User user = userService.findOne("testUser@mail.com");
        assertNotNull(user);
        User admin= userService.findOne("testAdmin@mail.com");
        assertEquals(admin.getEmail(), "testAdmin@mail.com");
    }

    @Test
    public void testTask() {
        User user = userService.findOne("testUser@mail.com");
        List<Task> task = taskService.findUserTask(user);
        assertNotNull(task);
    }

    }

Here is the image of the error java.lang.NullPointerException