Stall warning system uses angle of attack and air speed to calculate a stall, and a stick shaker and aural warning. All of these can be tested on the ground, and often are. I’ve been on several test flights after heavy maintenance, and never has an intentional stall been part of it.
Certainly, but it's dependent on the manufacturer, the maintenance performed, and who the aircraft is being delivered back to. Multiple sites highlight that this specific incident involved a test of the stall warning system. For example:
"A Beech Hawker 900XP jet crashed while doing a flight test of a stall warning system... The accident occurred during a positioning flight that happened after completion of maintenance of the anti-icing component on the leading edge of the wing."
https://ifairworthy.com/stall-warning-flight-test-turns-disastrous-video/
"The crew on a Hawker 900XP (N900VA) was performing a stall warning and systems check-in... The flight crew was planning to fly the plane... to perform a stall warning and system check, which is following the airframe manufacturer’s requirements. The requirements are listed in the pilot’s operating manual and include a required altitude of above 10,000 ft above ground level, 10,000 ft above clouds and below 18,000 ft mean sea level. The check flight can only be conducted during day visual meteorological conditions and with a good visual horizon, with the autopilot disengaged, an operative stall identification system, the external surfaces free of ice, an empty ventral tank and weather radar on standby..."
https://www.globalair.com/articles/hawker-900xp-conducting-stall-test-during-deadly-crash-ntsb-says?id=7043