This kata is a duplicate to katas such as https://www.codewars.com/kata/57fece4108d102ea65000bf6.

Initial code should be defn, not def.

To make it clear, you'd better put random tests in a separate scope (which is why the example i gave is named 'fixed', meaning fixed tests)

(deftest random
  (dotimes ...)
)

And katas on CW usually do 100 times random tests.

Yes, that makes a whole lot more sense! Thanks again for your help.

Thanks! It's my first Kata so I don't know what I'm doing yet.

Test fixture does not contain any test structures like

(ns solution)
(def insert [tree & values]
  ; code here
)


(ns test (:require [clojure.test :refer :all] [solution :refer :all]))
(deftest fixed (is (= nil (insert nil))))

Thus the result panel will only display

Time: 1963ms

and no one will be able to pass the tests.

Sorry! This is my first attempted port. I will fix it and try again.

Sorry. The test cases are not a faithful port of the original Kata and there are no random tests.

https://github.com/Codewars/codewars.com/wiki/Kata-Translations#remarks-on-translating

Have you read the descriptions?

It seems like we are guaranteed to have exactly one different number (odd or even).