Well, many languages. I'm adding more as I go! While you can be consistent on your own projects and always have makefile, you can't always do that on other projects. Because it chooses a test command based on the files in the directory, it's a consistent interface between projects you own and projects you don't.I also wrote about the project in more detail on my blog: https://xavd.id/blog/post/run-every-test/