I do hope this is only after minor repairs, and that after taking apart and reassembling an airframe the plane first goes up and comes down again with only a test pilot/crew.
We then sat on the plane for several hours while a crew (replaced|repaired) the APU. It was pretty disconcerting to be sitting there and hearing the drilling and grinding emanating from the hold and reverberating throughout the plane.
This was in 2000, so my memory is a bit vague but I do recall taxing out at one point, pushing up the power and then powering back down and returning to the gate for more work.
When the repairs were finally done, we immediately took off and made it across the Atlantic safely. It was one of the stranger air travel experiences I've had.
Actually, a test flight is the gold standard in aviation for return to service.
I've done maintenance test flights for operators. Basically you read the maintenance logs and do a test flight to exercise whatever was changed.