(use test data-generators)

(define (make-falsified-property-condition value rounds)
  (make-property-condition
   'falsified-property
   'value value
   'rounds rounds))

(define (check-property property value round)
  (handle-exceptions exn (signal
                          (make-composite-condition
                           (make-falsified-property-condition value round)
                           exn))
                     (property value)))

(define (run-property-test sample-size gen property)
  (let ((rounds 0))
    (gen-for-each
     sample-size
     (lambda (value)
       (set! rounds (add1 rounds))
       (unless (check-property property value rounds)
         (signal
          (make-composite-condition
           (make-property-condition 'exn 'message (sprintf "falsified with ~a after ~a try(s)" value rounds))
           (make-falsified-property-condition value round)))))
     gen)
    #t))


(define current-sample-size (make-parameter 100))

(define test-property
  (case-lambda
    ((description gen property)
     (test-assert description
           (run-property-test (current-sample-size) gen property)))
    ((description amount gen property)
     (test-assert description
           (run-property-test amount gen property)))))




;; example
(test-property "it's always positive" 100 (gen-transform abs (gen-fixnum)) positive?)
(test-property "it fails" (gen-fixnum) positive?)