Doctest.el or testing your pure Elisp functions in your docstring

A little time ago I have submitted code-compass to melpa (hopefully it gets approved soon). That gave me the opportunity to discover my reviewer repositories and I found a super cool little Emacs package: doctest.el.

This lets you write (and run) a test in your symbols documentation strings.

For instance, you can define a function like this:

(defun my-add (a b)
  "
>> (my-add 1 1)
=> 2"
  (+ a b))

and when you use doctest-here on the >> (or just doctest-defun), you would have your assertion evaluated.

I liked it so much that I roughly patched a few shortcomings:

• make it work for symbols defined in buffers that are not saved to a file
• support multiple lines for input and output in assertion

You can find my fork here, if you like it and look for those improvements.

Happy testing!