(defparameter *tests* nil)

(defstruct example in out about (failp nil))
 
(defun eg (in &key (of "example") (out 'any))
  (make-example :about of :in in :out out))

(defun egs (key &rest l)
  (if (cdr (assoc key *tests*))
      (setf (cdr (assoc key *tests*)) l)
      (push (cons key l) *tests*))
  key)
(defun eg0 (key &optional (all-tests *tests*))
  (cdr (assoc key all-tests)))


(defun demo (key &optional (s t) (all-tests *tests*))
  "(demo key)     ;; run tests from key, output to screen.
   (demo key nil) ;; run tests from key, suppress output
   return number of failed tests"
  (let ((n      0)
	(failed 0)
	(all    (eg0 key all-tests)))
    (dolist (x all failed)
      (incf n)
      (format s "~%;;;; ~a) ~a~%;IN:   ~a~%" 
	      n (example-about x) (example-in x))
      (let* ((want  (example-out x))
	     (got   (eval (example-in x)))
	     (happy (or (equalp want 'any) 
			    (equalp got want))))
	(if (example-failp x) 
	    (setf happy (not happy)))
	(format s ";GOT:  ~a~%" got)
	(cond (happy (format s ";ok~%"))
	      (t     (format s 
			     ";WANT: ~a~%;BAD !!!!!!!!!!!!!!!!!!!~%" want)
		     (incf failed)))))))	  

(defun demof (key file)
  (with-open-file 
      (*standard-output* file   
			 :direction :output
			 :if-exists :supersede)
    (let ((n (demo key)))
      (format t "~%;failures = ~a~%" n))))

;;;;
(egs :demo
     (eg '(+ 1 2)
	   :of "define an example"
	   :out 3)
     (eg '(+ 2 3)
	 :of "define an example with any output")
     (eg '(+ 10 20)
	 :of "define a failing example"
	 :out 0)
     (eg '(+ 2 3))
     (eg '(+ 7 3))
     )