It is important to frequently test your bilge pumps by switching from the automatic to manual position on the bilge pump switch. However, this doesn't guarantee that the pump will work when unattended. You should also check the automatic float switch by manually raising it to make sure that it turns on the pump.
Also, check for debris or corrosion that might keep it from floating up properly. If this switch fails the pump won't turn on and your boat could take on sufficient water over time to do serious damage.