Should native validations be tested in rails?

Question

Everybody knows that automated testing is a good thing.

Not everybody knows exacly what to test.

My question is if native validations like validate_presence_of,

Answer 1

Are you planning to write unit tests for every single Ruby operator and API method as well?

Your unit tests should test your own code, not other people's - that's their job, why duplicate their work? And if you don't trust them to do their job well, why are you using their code?