elm-verify-examples VS phobos

> Examples in documentation can (for some doc frameworks & languages) be set up to run as tests, ensuring they stay current and actually work.

As an example, in Elm (as in many languages) your publicly exposed functions in a package (a.k.a. library) are required to have documentation comments. This often includes a simple example because, well, it's easy to grasp. The build tool elm-verify-examples runs all of these examples and verifies that the output is what you say it is. It pretty cleverly uses the inline comment delimiter as the start of an arrow so that the rendered code listing in the example is still syntactically correct.

https://github.com/stoeffel/elm-verify-examples

Unit-tests are built into the language, as is comment-based documentation—put those two together and you get unit-tests as documentation examples built into the language; all it takes is to put a documentation comment (which can be blank) right before a `unittest` block after a declaration.

E.g. the examples for the D standard-library's `curry` function are just unit-tests: the docs: https://dlang.org/phobos/std_functional.html#quickindex.curr... the code: https://github.com/dlang/phobos/blob/42b8c65ccfd35c863f7cedf...