And a poisoner's kit. And an herbalism for poisons derived from plants and potions pf healing (you need proficiency withthe kit to make the potion, it makes sense to me it ought to be used to identify it).
It might also make sense that merchants will sell field identification kits like get used in today's world by cops to id cocaine, etc. So if an adventurer finds something he thinks might be a potion of enlarge, he pours a drop into the test kit, which changes color (or expands!) if the test is positive, and wasted if negative.
You might create test kits that are broader than that. Maybe showing positive on a whole school, or positive if the potion is beneficial, positive if it's a plant-based poison, etc, etc.
. . . And I think this idea is gonna find its way into my game very soon.