Sorry for the shameless self-promotion, but maybe someone might find this tool of some use…
I just released CGTest, a simple command-line tool to run solo training puzzle tests in batch mode, using your local dev and runtime environments. With a single command, you can run hundreds of tests for your code, even if written in multiple languages, for multiple puzzles (or projects), and for multiple test cases per puzzle.
CGTest was successfully used for running bash, c, c++, d, dart, f#, fortran, go, groovy, haskell, java, kotlin, lua, ocaml, pascal, perl, php, python, ruby, rust and scala tests. (I still have some issue with c# and js.) It should work in Windows, Linux, Mac, etc.
The repo also includes 200+ test cases for CG puzzles, I will add more later.