MongoDB, Apache Ignite, Cassandra, MariaDB - we've head at least of one product from this list. There are a lot of manuals and posts on stack overflow, habr about them. All of them are distributed systems - distributed data base, distributed cache and so on. We will focus on the testing of such systems (yes, I'm talking about Jepsen).
Jepsen it is module of Clojure (it's like a Lisp but for JVM). This module have a lot of useful code, that break the brain of anyone who not familiar with s-expressions. It difficult but it intresting!
I will tell about Jepsen as a module of Clojure, about testing environment and show some real examples of tests.