Great, that's a good news ! i'm going to try to test it and will give you feedback.
Thanks.
Hello Pascal,
Just to let you know, I have a plugin for such a problem. It's at https://moodle.org/mod/forum/discuss.php?d=373315
I am investigating coderunner for testing programs, but for generating non programming exercises with random variables, my approach should be easier. Although still experimental, the plugin does not require a server and is quite lightweight.