Garage vehicle doors are heavy. I have talked to people in my community who have had pets killed by motorized garage doors that did not have the proper safeguards in place to protect against catastrophic accidents. People, obviously, can be killed by these doors as well.
The short video, that I shot recently at a home inspection, is an example of what you don't want to see when you are testing auto-reverse on impact at a motorized garage vehicle door. This is the floor test. A vehicle door should reverse if it strikes an object, 1" or greater, that has been placed flat on the floor under the door track.
Watch what happens here.
Other standard "reverse" tests include reverse on impact at mid-height as the door is closing. And a third test verifies proper function of the sensor eyes that should be mounted at the sides of newer vehicle doors.
Warning -- Not all doors, it depends on age and condition, should be tested in this manner. Many older doors may reverse only at mid-height, or not at all. Such doors are, by today's standards, considered to be unsafe.
Performing these "impact" safety tests at an old door, or at a door that is out of adjustment, may result in damage to the door, related property damage or injury so testing should be done by a trained professional.