There are also tools like lein-test-refresh https://github.com/jakemcc/lein-test-refresh that figure out what needs to be reloaded automatically. You start it up, it watches your namespaces for changes, and reruns tests as needed. As a bonus it can even hook into your OS notification system and let you know if any tests fail.
A lot of editor integration will handle reloading and test-running for you (including VSCode's calva extension, Cursive, and Proto REPL for Atom, although it's less "automatic" than the others).
There are also tools like lein-test-refresh https://github.com/jakemcc/lein-test-refresh that figure out what needs to be reloaded automatically. You start it up, it watches your namespaces for changes, and reruns tests as needed. As a bonus it can even hook into your OS notification system and let you know if any tests fail.