Okay, will create it. Also, some other assertions might be useful such as assertIsAnInteger, and asserting if numbers are >, >= , <, <= or within some range. I'm not sure how often these are used though. Will stick to assertNotEmpty for strings first and add those if they appear more.

Just to confirm, there are many assertion messages that are magic strings. Is there some policy that only commonly used strings be made constants(since there are alot, and may only be used once or twice), or are strings that are shown to users only made constant?