I have seen some problems recently with making shops and signs allowing you to buy items from chests next to them for a price on the other chest. with that said I think it would be great to be able to check your shop signs your self , thanks for your time.
If I am not mistaken, he would like to be able to test (so buy from) your own shopssigns, because he had some problems that signs and chests were interacting with each other
I believe this was a "feature". When the owner tried to break his sign, he/she bought materials from himself. When he/she right clicked the sign, he/she was brought into the chest. This was annoying. -1. Here are where shop signs work. (Barrier blocks are used in SP)
I more or less mean a simple /test and then u can click ur sign and see what it says not actually buy from it then do /testdone.