sql.clj

(let [jdbc-url (System/getenv "JDBC_DATABASE_URL")
      ds (jdbc/get-datasource {:jdbcUrl jdbc-url})]
  (with-open [test-conn (jdbc/get-connection ds {:auto-commit false})]
    (jdbc/execute! test-conn
                   ["DELETE FROM app_user"])
    (jdbc/with-transaction [app-conn test-conn
                            #_{:rollback-only true}]
      (let [sp (.setSavepoint app-conn)]
        (try
          ;; here is my app-code; so it should use `jdbc/with-transact` when it needs
          (jdbc/with-transaction [tx app-conn]
            (jdbc/execute! tx ["INSERT INTO app_user (username) VALUES (?)"
                               (UUID/randomUUID)]))
          (finally
            ;; throws: ERROR: ROLLBACK TO SAVEPOINT can only be used in transaction blocks
            (.rollback app-conn sp)))))
    ;; should be empty again
    (jdbc/execute! test-conn
                   ["SELECT * FROM app_user"])))