How to safely upgrade and roll back a Clojure dependency?

To upgrade a Clojure library safely, follow these steps:

1. Check the current version in deps.edn (or project.clj if you use Leiningen).
2. Update the version string to the newest release you want to test.
3. Run the project’s test suite and any manual verification steps (e.g., start the REPL, exercise core functions).
4. If tests pass, commit the change; if they fail, revert the version change to the previous value.
5. To roll back, simply restore the original version string and re‑run the tests to confirm the prior state works.

Verification can include checking that the classpath resolves correctly (clj -Spath) and that the application starts without errors.