One might be easily impressed by the thousands of hours of both pilots, and easily believe that they should be amongst the most quailified to perfom those "test flights" (well, I would prefer the word "acceptance flights") Such an assertion would forget too easily that a significant percentage of that flight time (!) has been spent on autopilot, or reading magazines in the cockpit, or even sleeping, not mentioning going to the toilet or chatting with the flight attendants in the galley... and there is also the time spent on the ground.
So all those impressive flight hours dont't really mean a lot, as far as acceptance flights are concerned.
Now as rightly said by Goldfish85 and Ancient Geek, there are specialised crew for those duties - even if acceptance flights are more than ususally called "test flights" - and even the recognised test pilot schools like ETPS or EPNER have dedicated courses for acceptance pilots. They usually require 6 months, against 12 months for the full course. Also the big manufacturers (Airbus at least) have in-course programs, to allow selected pilots with recognised experience, to fulfill some of those flight duties after being issued with an appropriate qualification.
In any case, there will be a test card, with points, and for each of them relevant safety parameters, altitude being of paramount importance.
And for stall approaches, there is a big idea : incremental, incremental....