CMake is a very cool buildsystem that can do a lot, you can use it to run tests, fetch sources, and everything else. The documentation is the only thing that I find quite suboptimal, they could really add examples in there and better explain things. Or at least have list of projects that they believe are using CMake correctly so one can have some guidance. It took me five years before I was comfortable writing CMake from scratch.
I had a boss who once quipped that CMake became much easier for him to understand and write once he realized it was just a really shitty version of BASIC with only global variables. (He later added "but two separate namespaces for them" because of the prevalent use of environmental variables as well as CMake-specific variables)
