I hear you all.
Though I have learned that airbus typically test the Alpha Floor, Overspeed amongst other protections as well as the systems; eg pressurization/depressurization (for the oxygen masks). These tests can also be learned from other channels and Airbus pilots know these protections.
As you have mentioned for test/acceptance flights there is a predicated checklist for them to follow, be it accepting the aircraft from Toulouse or from another airline and they have specific personal and expertise to sit in for these flights. Normal line pilots will never have a chance to see what they do though nor have the chance to perform them. Line pilots fly and ensure the safety of line flights.
Thanks for the inputs and views.