There's a gem for Ruby that does a limited version of this: https://github.com/testdouble/suture https://github.com/testdouble/suture Suture is geared towards

There's a gem for Ruby that does a limited version of this: https://github.com/testdouble/suture https://github.com/testdouble/suture Suture is geared towards refactoring, so it doesn't do it for every function at once, and instead you have to specify methods manually.