Use midje for testing

test/book/core_test.clj

@@ -0,0 +1,13 @@
+(ns book.core-test
+  (:require [midje.sweet :refer :all]))
+
+(facts "big fact"
+  (fact "about trivialities"
+        (let [expt 3]
+          (inc 2) => expt
+          (inc 2) => expt))
+
+  (fact "about trivialities 2"
+        (let [expt 3]
+          (inc 2) => expt
+          (inc 2) => expt)))