Pyret: A new programming language from the creators of Racket
"""Pyret makes testing a natural part of the programming process. Functions can end in a where: clause that holds unit tests for the function. These assertions are checked dynamically."""<p>Fantastic idea! I'll keep that in mind, should be fairly easy to extend Lisps or other AST-Macro enabled languages (Elixir, Julia, Python) with such a functionality. I really like that. It makes it easy to work on a function and code tests down without switching contexts (files, workspaces, etc)