Testing a function returning boolean

Question

I have possibly the most simple test failing with a rather confusing message for Clojure newbie.

(ns leiningen.booltest
  (:use clojure.test))

(with-test
  (defn bool-function [] 
    (true))

  (is (= (bool-function) true))
)

ERROR in (bool-function) (booltest.clj:10)
expected: (= (bool-function) true)
  actual: java.lang.ClassCastException: java.lang.Boolean cannot be cast to clojure.lang.IFn

Answer 1

You are calling true as a function: (true) on line 3 of your with-test expression. It should simply be true, without the surrounding parentheses.

You can further simplify your expression, since bool-function already returns true:

 (with-test
      (defn bool-function [] 
        true)
      (is (bool-function)))