If you want to test the smoke detector, locate the test button on the front or side of the unit. Press and hold the button for a few seconds to ensure the alarm sounds. If it doesn’t, you may need to replace the battery or have an electrician check the wiring in the detector. If you want to test a smoke sensor, buy canned smoke and spray the smoke onto the detector, being sure to follow the directions on the container. Keep reading for our reviewer’s tips on how often you should test your smoke detector!