The answer to 'how to test smoke detector' is to test your smoke detectors monthly to ensure they are working properly. Start by pressing and holding the test button on the smoke detector until the alarm sounds. This tests the battery and the alarm function. You should hear a loud, piercing sound that indicates the smoke detector is functioning as it should.
If the alarm does not sound, replace the battery and test it again. If it still doesn't work, the smoke detector may need to be replaced. It's also a good idea to vacuum or wipe down the smoke detector to remove any dust or debris that could interfere with its sensors. Smoke detectors should be tested monthly and batteries should be replaced at least once a year, or more often if the detector chirps to indicate a low battery.