No man there was no test. Sangwoo is someone you couldn't trust, and with good reason (he likes to murder people in his basement*whispers*)...so that's why people are waiting for the catch, but there isn't any. He just wants Bum to appreciate him, for now anyway, depend on him and so on and so forth.
Well.. Sangwoo said himself you shouldnt trust him xD. That reaction when bum didnt gave him the frog, he seems like he was internally planning something (killing bum/make him his accomplice/sacrifice him) and the moment bum made the wrong step, he was about to throw the picture until he saw bum smiling.
Ahh sangwoo really.. He's still testing bum, and the frog thing he associated with some trust test.. Like yo sangwoo what reaction do you want to see? he's so complicated