XXX, this is our point totally and we are in agreement. Read manual (MEL etc) and if it says do X to repair. You do X. If it says don't have to repair as long as conditions Y are met, you make sure conditions Y are met, aircraft is signed of and then you go flying.
If anywhere it said test flight is required one would be carried out. If none required it will go straight back into service.
Assuming you are a heli pilot and perhaps you have to test fly after lots of snags but on modern airliners most problems either cause the aicraft to be grounded or continue to fly in accordance to the MEL. As long as MEL conditions are met we take it.
This is what the previous comment about being happy will be. Not just a case of I reckon it will be ok but a case of being happy that all the legal requirements are met!
Also if the aircraft is grounded and repairs carried out, once it has been signed off the aircraft is then flown on a commercial flight with passangers on. Why, because thats legal and safe. No test flight required (in most cases).
Ground runs are often carried out for many engine snags. Engine performance satisfactory and it is signed back into service. Very very few cases actually require a test flight by a test pilot. Why do you think most airlines only have a handful of guys signed off to test fly? Its quite an uncommon occurance. If a test flight is required though it will be done.
PJ2 is totally correct and sounds like he knows what he is talking about. I would be happy to fly with the chap!!! When he's happy I would be happy!