I'm looking into some coverage tools so we can report test coverage (like in pull requests!) and Bob was saying @bgoodri had done this at one point? I have some nice coverage printing out but right now it's on a per test binary basis, which isn't so great when the tests for a single idea are spread out across up to 9 files (across prim/scal up to fwd/mat), etc. clang has some built in that I'm using instructions from here for: https://alastairs-place.net/blog/2016/05/20/code-coverage-from-the-command-line-with-clang/
An interesting move might be to try to compile all the unit tests into a single gtest binary (which would solve my current issue). I might expect this to speed up compile times, even...