User user1 = storage.get(User.class, user.getId());
if (!user1.getName().equals(user.getName())) throw new Exception("Users should be equals!");
user.setAdmin(false);
storage.save(user);
User user2 = storage.get(User.class, user.getId());
if (!user.getAdmin().equals(user2.getAdmin())) throw new Exception("Users should be updated!");
storage.delete(user1);