Falderal is a file format for literate test suites. It is particularly suited for documenting programming languages (or other specifications of ways to transform text) and testing their implementation(s) in a language-agnostic fashion. The dumbed-down sound-bite version: "doctests for DSLs". It can be embedded in both Markdown and Literate Haskell.
py-falderal in the Falderal distribution
Issue tracker: on github