The core is largely independent of clojure.test, after all we handle cucumber or cljs tests as well that aren't written in clojure.test, so the core test runner machinery is independent. The main compromise is that we do still dispatch through clojure.test/report, so that existing third party reporters still work. That seemed important for adoption, not to break that expectation. Unfortunately clojure.test/report isn't really designed with this use case in mind, and so we have to do some funky things to make it all work as expected. I think I still stand by that choice.