At a basic level any Lisp-like with an editor integrated REPL lets you put your cursor over the `greet` invocation below and evaluate it, and have the results shown in the manner of your choice (IDE window, inline temporary comment, etc).

This is all in the file as saved to your version control:

  (defn greet [name] 
    (-> (str "Hello, " name "!")
         println))

  (comment
    (greet "worldsayshi"))

It's 90% of the way to being a test already, just from the typical workflow.