Totally agree that code coverage is not a sufficient metric for quality, but it's still an interesting one.

At my company we have this language that is not mainstream (Oberon) and therefore there was no code-coverage reporting at all. I found this paper and realized it was super easy to write a minimal code-coverage analysis from our AST parser and code formatter (internal tools). Somehow it had never occured to me that it was this simple.

The transition from "no code coverage at all" to "seing which module is covered and which is not" was really insightful !