(let ((a 'ok))
  (and nil (set a 'fail))
  (expect "and - Short circuit" (equal a 'ok)))

;; (let ((a 'ok))
;;   (or t (set a 'fail))
;;   (expect "or - short circuit" (equal a 'ok)))

(expect "and - returns last value if all operands evaluate to true"
        (equal (and t 'ok) 'ok))

(expect "and - returns nil if any operand evaluates to false"
        (null (and nil t)))