No tests. No documentations (even in Russian it's not enough). It is not only KPHP but also some their engines written in C. Like Search, Queue, Storage, Text and so on. All of it in just one repo.
It is a great example when sports programming works (VK.com #26 Alexa Rating).
Russian-language documentation is available at [[docs/ru/]].
English documentation not available yet, sorry.