Clojurians Log v2

Hey there! I know how to write tests in clojure(script) however I am not so sure on what to test, especially on the frontend side of things. What are the typical things that one should test in a Clojurescript app? I have a cljs app which uses reagent which has unit tests in place for the API calls. What other things should I unit test for? What things should be tested end to end (Components? JS library integration?) Should components have unit tests? If so how do I go about them