This is done several ways. Mostly this is due to information provided to us by the parent. i.e. so and so hit someone on the bus, could you please speak to my child. Parents often pass on this information to us because children for some reason don't seem to listen to their parents, but will listen to other adults.
And while we don't do it every testing, we do send home a form that must be signed by both a parent and teacher to indicate proper behavior at home and at school.
Adult bad behavior often results in being asked to leave the school.