keys_in_test.clj

(ns keys-in-test
  (:use [clojure.test]))

(defn keys-in
  "returns all possible keys in a nested map"
  [m & ks]
  (if (map? m)
    (reduce into ks
      (for [[k next-m] m]
        (let [next-k (vec (conj (last ks) k))]
          (keys-in next-m next-k))))
    ks))

(deftest keys-in-test
  (let [nested {"a" {"b" {"c1" 1 "c2" 2}}}]
    (is (= (set [["a"] ["a" "b"] ["a" "b" "c1"] ["a" "b" "c2"]]) (set (keys-in nested))))))