The alias highlight the exact functions being tested in the body of the code. This provides a visual way to separate functions under test with other test functions, especially if there are helper functions or vars used for test data.
(require '[clojure.test :refer [are deftest is testing]])
(require '[practicalli.playground :as SUT])
SUT alias - system under test
SUT, meaning system under test, is a common convention in software testing. Using the SUT alias makes it easier for developers to see which functions from the application are being tested at a glance.