Rukia is a C++ library to generate paths (or traces) in automata according to a defined coverage criterion. Thus, it provides generic algorithms to count the number of elements to be covered, and generic algorithms to explore automata at random while ensuring a uniform distribution among those elements.
Rukia is a free software: see the Lesser GNU Public license (LGPL). So basically, this means that you are free to use it anywhere but you need to make available any modification you did.
Rukia is also deposited in the Agency for the protection of programs (APP):