Questions related to testing Firebase functions

[dvdhfnr]

Hi,

I understand that testing the Firestore security rules works fine with a "fake" project id (TEST_FIREBASE_PROJECT_ID).

Why do we need the real project id for testing firebase functions with the emulator (REAL_FIREBASE_PROJECT_ID )?
Are there any plans to get rid of this; or is there a good reason why it is like this?

Related, the presented colab "combines" the tests of the security rules and the functions in one file. The unit test documentation at https://firebase.google.com/docs/functions/unit-testing describes a fundamentally different workflow. Which is the recommended one? Is one of them outdated?

Thanks a lot for your answers in advance!