@Test
     public void test() {
         for(User user : users) {
            if(!MongoHelper.delete(user, "users"))
                TestHelper.failed("delete failed");

            if(MongoHelper.fetch(user, "users") != null)
                TestHelper.failed("user was not deleted");

            System.out.println("Deleted user id: " + user.getId());
         }
         TestHelper.passed();
     }