You can test the auto braking safely. I saw a show that created dummy cars from a light wood frame covered with cardboard, then painted to look like a rear end with fake lights. Choose a safe street or parking area that has space to run and test. Set up the dummy with space behind it. Then run at it at 30 MPH or better. If your car stops, it passed the test. But if it doesn't, the dummy will fall over, and running the car over the cardboard will not damage the test car or its bumper.
You can do the same with dummy pedestrians and test the pedestrian detection system.