Cool. I actually want this for both code and test development. For me the REPL is the first place that sees an implementation- multiple implementations, weighi

Cool. I actually want this for both code and test development. For me the REPL is the first place that sees an implementation- multiple implementations, weighing various design factors- which then gets copy pasted into a source file and then REPL state reloaded (the Clojure "reloaded" workflow), and then the capability offered by the updated implementation exercised with test-like code in the REPL- which then as you describe should magically get into the test suite source for reuse. Good luck. What language are you doing this work in?