Full Idea
A proposed test for presupposition is the 'Hey, wait a minute' test. S presupposes that p, just in case it would be felictious to respond to an utterance of s with something like 'Hey, wait a minute - I had not idea that p!'.
Gist of Idea
A test for presupposition would be if it provoked 'hey wait a minute - I have no idea that....'
Source
Ofra Magidor (Category Mistakes [2013], 5.3.1.2)
Book Reference
Magidor,Ofra: 'Category Mistakes' [OUP 2013], p.119
A Reaction
[K. Von Finkel 2004 made the suggestion] That is, you think 'hm ...this statement seems to presuppose p'. She says the suggestion vastly over-generates possible presuppositions - unlikely ones, as well as the obvious ones.