Earlier quoted context omitted.
wheezy is a version alias for v7. testing is testing. it points to the version that is on testing, be it 7-wheezy, or 8-whatever. the only exception to the rule is 'sid'. debian sid is always the bleeding edge, it never becomes a proper version. btw, i hate every versioning alias scheme that does not force the number to appear. such as debian, ubuntu, android... it's all just idiotic.
Why is a number more useful than how Ubuntu or Android do things?
Now consider trying to make similar determinations if you know you're running "Gingerbread" but the latest version is "Jelly Bean", or if you're on "Intrepid Ibex" and the latest version is "Raring Ringtail".
It's even worse on Ubuntu, where they've chosen a reasonable, useful numerical versioning system (year.month), but then obscure it with stupid codenames.
IMO it's also much more difficult to remember the codenames. I had to verify that Android 4.2 was still called Jelly Bean and though I knew the latest Ubuntu was 13.04, I had to look up its codename altogether.
The fact that these projects continue to have underlying "developer use only"-type numerical versions only further emphasizes the utility of these. The codenames feel like a poorly-conceived marketing thing. I don't think most people have trouble remembering a coupled software package with a version number, like "Windows 7". I don't think they often say, "Oh crap, I know I had version 4 of something ... was it Android or Windows?"