Mix ordinary text and snippets of code in the same file and execute them as regression tests
copied from cf-staging / byexamplebyexample is a literate programming engine where you mix ordinary text and snippets of code in the same file and then you execute them as regression tests. It lets you to execute the examples written in Python, Ruby or whatever in your documentation and validate them. You can always be sure that the examples are correct and your documentation is up to date!