Prime Factors kata in Racket using recursion

prime-factors.rkt

#lang racket
(require rackunit rackunit/text-ui)

(define (prime-factors n)
  (define (factors acc canidate x)
    (if (equal? 1 x)
        (reverse acc)
        (if (zero? (modulo x canidate))
            (factors (cons canidate acc) canidate (quotient x canidate))
            (factors acc (add1 canidate) x))))
  (factors empty 2 n))

(run-tests
 (test-suite
  "prime factorization tests"
  (test-case
   "given a prime number it must return given prime number"
   (for/list ([prime '(2 5 7 11 13 17 23)])
     (check-equal? (prime-factors prime) (list prime))))
  (test-case
   "given a prime number times 2 it must return 2 and given prime number"
   (for/list ([prime '(2 3 5 17)])
     (check-equal? (prime-factors (* 2 prime)) (list 2 prime))))
  (test-case
   "given a complex number the product of its prime factors must equal given complex number"
   (for/list ([complex '(100 33 45 109872)])
     (check-equal? (apply * (prime-factors complex)) complex)))
  (test-case
   "given 1 its prime factors must be none"
   (check-pred empty? (prime-factors 1)))
  (test-case
   "given a complex number its prime factors must be sorted in ascending order"
   (for/list ([complex '(1010 10202 3333208 109872)])
     (let ([factors (prime-factors complex)])
       (check-equal? (sort factors <) factors))))))