This is a modified version of the famous light-bulb problem.
There are three switches in the hallway. turning on the switches in different combinations cause different light-bulbs in the room to turn on. There are six light-bulbs and from turning on all of the possible combinations, each light-bulb is turned on at most twice (in other words there are only two ways to turn on a light-bulb). We need to map the switches to the light-bulbs.
The only things we know is that flicking 1 switch causes 1 light-bulb to turn-on, flicking 2 switches causes 2 to turn-on, and flicking all 3 cause three light-bulbs to turn-on and if a switch turns on a light-bulb, that switch must be on to turn it on again (even if flicking 2 switches).
What is the fewest number of 'tests' needed to effectively map the light-bulbs to the switches?