Do you really think that just because you have automated tests, that your software is defect free? Tests (outside of generative/property-based testing, which is still under-utilised) aren't very good at finding bugs outside of regressions. Having said that, most Clojure code worth talking about does have automated tests.

In my ideal world, I would use expected-case Unit Tests to test the contract/requirements/interface. Regression tests to prevent fixed bugs from reappearing and generative tests to try and find bugs. I would write the expected-case tests before the code, use REPL testing while developing and finally write property tests after (once my code has evolved so that I understand the properties) and regression tests only as I fix bugs after the fact.