On Sun, Jul 27, 2014 at 11:02 AM, Alex Charlton <alex.n.charl...@gmail.com>
wrote:
>
> Matt Gushee writes:
>
> > I guess my explanation wasn't entirely clear, but that's pretty much
> > what I was already doing. I showed the equality predicate I was using,
> > which tests individual values in the list with = . I think my mistake
> > was in assuming that (current-test-epsilon) would apply to = in the
> > test environment. I'm guessing now that that is not the case.
>
> Ah, yes, I hadn’t understood how you were testing. You’re right that =
> does not get redefined to use current-test-epsilon. Instead you would have
> to use your own equality predicate that incorporates it. test defines its
> approx-equal? as:
>
> (define (approx-equal? a b epsilon)
> (cond
> ((> (abs a) (abs b))
> (approx-equal? b a epsilon))
> ((zero? b)
> (< (abs a) epsilon))
> (else
> (< (abs (/ (- a b) b)) epsilon))))
>
> Which you could then add to your predicate like so:
>
> (define (list= l1 l2)
> (and (= (length l1) (length l2))
> (let loop ((l1* l1) (l2* l2))
> (cond
> ((null? l1*) #t)
> ((approx-equal? (car l1*) (car l2*) (current-test-epsilon))
> (loop (cdr l1*) (cdr l2*)))
> (else #f)))))
>
Easier:
(define list=
(let ((approx=? (current-test-comparator)))
(lambda (ls1 ls2)
(and (= (length ls1) (length ls2))
(every approx=? ls1 ls2)))))
then
(test-assert (list= '(0.655 0.843 0.200 1.0) (parse-color "167,215,51" #f)))
or
(define-syntax test-rgb
(syntax-rules ()
((test-rgb expected expr)
(test-rgb #f expected expr))
((test-rgb name expected expr)
(parameterize ((current-test-comparator list=))
(test name expected expr)))))
(test-rgb '(0.655 0.843 0.200 1.0) (parse-color "167,215,51" #f))
--
Alex
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