public function testGetNotificationById()
 {
     $user = $this->users->random();
     $stu_id = $user->stu_id;
     // default case
     $result = $this->repository->getLatest10Notification($stu_id);
     $this->assertEquals(10, $result->count());
     $first_id = $result->sortByDesc('id')->first()->id;
     $this->assertEquals($result->first()->id, $first_id);
     // id = 10 range = 5
     $result = $this->repository->getNotificationBack($stu_id, 10, 5);
     $this->assertEquals(5, $result->count());
     $first_id = $result->sortBy('id')->first()->id;
     $this->assertEquals($result->first()->id, $first_id);
     // id = 20 range = -7
     $result = $this->repository->getNotificationFront($stu_id, 20, 7);
     $this->assertEquals(7, $result->count());
     $first_id = $result->sortByDesc('id')->first()->id;
     $this->assertEquals($result->first()->id, $first_id);
 }