Sorry, my post was way too harsh.
It would be nice to be able to write 100% new code - to never have to deal with legacy code or work with other people’s libraries and frameworks. But that’s just not the real world.
Even with new code, sometimes you have to deal with a library or framework that imposes undue object construction/usage constraints. Or sometimes you have to integrate with an external production system and do not have access to a non-prod instance. The fact is that mocking has its place, and unfortunately somethings are difficult or even impossible to mock with the current tools.
It’s way too late in the evolution of the language, but I wish the designers had taken advantage of the opportunity they had at the beginning and built in capabilities to make full testing much easier.