I (the author) have been doing a lot of embedded development lately, and in those cases you really can't assume very much beyond core ANSI C features. That's also why greatest doesn't do any dynamic allocation, at all. There's a relatively small struct for the current testing progress, and everything else can easily run out of ROM.

My primary goal with greatest is to assume as little as possible, and avoid imposing any additional constraints on projects just because people want to test them. I also want the implementation to be very transparent -- it's just a 600-ish line header file, carefully documented. It's a major pet peeve of mine when I have to work around features that try to automatically be helpful, but have edge cases that break down in opaque ways. (Build systems tend to be particularly bad in that way.)

Also, I'm beyond shocked that the name wasn't already taken. ;)

One of my upcoming tasks is making stdio optional in greatest, because printf doesn't do you a whole lot of good if you're running it on an Arduino or something, but in those contexts automated testing is especially valuable.