The test button on your unit is there to test the quality of the detector’s battery, not the effectiveness of the unit. After your unit has been cleaned and you have determined your battery is providing your unit with enough power, it is also important to test out if your smoke detector can detect smoke.
It is way more simple than burning some toast for breakfast. A small open flame held under the smoke detector will do this trick. This includes a lit match or a small candle. The lit flame may not produce enough smoke to set the alarm off. Blowing out the flame and allowing the smoke to rise to the alarm should do the trick. If the alarm does not sound either way, then it is time to think about replacing the unit.