1. The original documentation tool I wrote for Atom, Biscotto, kept track of the number of undocumented classes / methods: https://github.com/gjtorikian/biscotto/blob/59f48ba2621a92ae... . It was hooked up to CI, and if the count fell below a certain threshold, the test failed.

2. Right now, we're exploring into working with JSON schema as a means of providing both testing validation and accurate documentation. If the schema says "This REST method expects a parameter of this type," it becomes very easy to write a test to enforce that behavior; documentation can be easily generated from it; and of course your production code is safer for it.

I'm a huge fan of introducing more cross-overs between testing and documentation. I think a lot of time is spent on "clever" (and subjective) validations like http://www.hemingwayapp.com/, but not enough time is spent on basic content checks. It's very easy to drift code, tests, and docs apart. We need to start thinking about all three of them working together.