In a fire drill do they test the sprinkler system

I know they usually test the alarm system but do they actually use the sprinkler system in a drill or is it a waste?

Fire drills are designed to teach a disciplined respond to a real fire situation by all persons in the premises where the fire may occur.
When fire drills are carried out as a training method for fire fighters, all the hydraulic systems are tested except the sprinkler systems (for wet systems). The elements comprising the system goes from hydrants to hoses, siamese valves, pumps and controls, evacuation methods, first aid etc.
In a fire drill they don't test the sprinkler system, the reason is because if they did, a large damage may be done on the equipment and almost all things exposed to the water in the system ( in a wet system).
The sprinkler system is considered operational if all the gages show appropriate readings, the valves are operational, sensors are functioning etc.
The sprinklers are continuously checked preventing accidental openings or faulty fuses that may render it useless for clogging and rust.

The vast majority of sprinkler systems are not triggered by the fire alarm. Most fire sprinklers are individually activated by heat. The only time systems that all deploy at once (deluge systems) are used is in situations when even a small fire poses more of a risk than water damage, like a storage area for gas cylinders.

No, they don't check the sprinklers during a fire drill. A fire drill is simply to check the alarms and to get people used to doing what they're supposed to do in that situation.
However, the local Fire Marshall does check the sprinkler systems at least once a year. Although I wouldn't be surprised if it's more often for schools.
They don't actually set the sprinklers off, though. That would ruin all the textbooks and computers and many other things.....

Have you ever gotten wet during a fire drill?