Title says unit tests. But to GP's point, it isn't really automatic, the developer still decides what to test. It is transforming REPL logs, not generating tests based directly on the code (which isn't useful in my experience).

To be honest, my development REPL logs have a lot of junk, so it would be extra work to write a clean one, and then make the right assertion (maybe I was looking for "even number" not "exactly 132"). Lisp-y REPLs are friendlier than some, but it would be cool to associate it with something like a notebook where it is easier to update imports/mocks/etc out of order. Cool idea though.