How to write non-brittle unit tests?

Question

Software testing

Pseudocode:

class UserRepository {
    constructor(private db: ORM) {}

    saveUser(user: Profile) {
        var username = user.username();
        var hashcode = user.getHashCode();
        var bio = user.getBio();
        var birthdate = user.getBirthdate()

        return db.save(new User({username, hashcode, bio, birthdate}));
    }
}

The question is how to test it? Just check that the method is being called db.savewith new User({username, hashcode, bio, birthdate})? I'm afraid that it will turn out to be a useless fragile test that will break when a new User parameter is added. Or is it the norm?

Answer 1

The question is should it be tested? Because all this class does is call another method, having previously converted the arguments. In my opinion, this is a classic humble object .
But if you really want to test it, then yes, we have no other option, you need to check that the save method is called (and optionally check that the correct arguments are passed to it). If you check the arguments, then when you add a new field, the test will break - well, it should have broken, right?