Roman numeral kata in Clojure

kata.clj

(ns roman-numeral-converter.core
  (:require [clojure.test :refer [deftest is run-tests]]
            [clojure.string :refer [replace]]))

(def numeral-mapping {1 "I" 5 "V" 10 "X" 50 "L" 100 "C" 500 "D" 1000 "M"})

(defn arabic-to-roman [n]
  (loop [[x & xs :as all] (-> numeral-mapping keys sort reverse)
         romanised ""
         num n]
    (if x
      (if (>= num x)
        (recur all (str romanised (get numeral-mapping x)) (- num x))
        (recur xs romanised num))
      (-> romanised
          (replace "IIII" "IV")
          (replace "VIV" "IX")
          (replace "XXXX" "XL")
          (replace "LXL" "XC")
          (replace "CCCC" "CD")
          (replace "DCD" "CM")))))

(deftest test-one
  (is (= (arabic-to-roman 1) "I")))

(deftest test-five
  (is (= (arabic-to-roman 5) "V")))

(deftest test-ten
  (is (= (arabic-to-roman 10) "X")))

(deftest test-fifty
  (is (= (arabic-to-roman 50) "L")))

(deftest test-one-hundred
  (is (= (arabic-to-roman 100) "C")))

(deftest test-five-hundred
  (is (= (arabic-to-roman 500) "D")))

(deftest test-one-thousand
  (is (= (arabic-to-roman 1000) "M")))

(deftest test-888
  (is (= (arabic-to-roman 888) "DCCCLXXXVIII")))

(deftest test-889
  (is (= (arabic-to-roman 889) "DCCCLXXXIX")))

(deftest test-zero
  (is (= (arabic-to-roman 0) "")))

(deftest test-four
  (is (= (arabic-to-roman 4) "IV")))

(deftest test-decending-order-tally
  (is (= (arabic-to-roman 16) "XVI")))

(deftest test-upper-limits
  (is (= (arabic-to-roman 3999) "MMMCMXCIX")))

(run-tests 'roman-numeral-converter.core)