What should be ensured when testing the smoke detector?

Testing the smoke detector should indeed ensure that the alarm sounds. This is crucial because the primary function of a smoke detector is to alert occupants to the presence of smoke or fire, which can be life-saving in emergencies. By confirming that the alarm sounds during a test, it's verified that the device is operational and ready to function properly in the event of an actual fire situation.

Other aspects of the detector, such as cleanliness or the presence of flashing lights, are also important, but they do not directly indicate the device's primary purpose of sounding an alert when smoke is detected. Therefore, while those factors can contribute to the overall functionality of the smoke detector, the most crucial aspect during testing is ensuring that the alarm successfully signals its alert function.