For me it is to leverage our existing testing tools: Rspec and Cucumber to test our Clojure libraries. The team I'm on already has a lot of experience with those two testing tools, and our analysts and QA personnel are able to understand tests written in those two tools. My experience has not been the same with JUnit and the Clojure based testing libraries -- developers are fine with it, but non-devs tend to provide very little input for unit or clj based tests. I think the imperative nature of those test are too dense or they say too much about how rather than what is being tested.