[plt-scheme] HTDP: Testing programs

Shriram's saying that the design recipe demands the creation of  
examples *before* you create the function. The idea is that this  
scales up to larger development efforts, too.

In principle, a design looks like this:

;; f->c : Number -> Number
;; convert a fahrenheit temperature to a celsius temperature

(check-expect (f->c 32) 0)
(check-expect (f->c 212) 100)

(define (f->c f-temp)
  (cond
    [(= f-temp 32) 0]
    [(= f-temp 212) 100]
    [else f-temp]))

;; ---

Over the years, HtDP and drscheme have gotten a bit out of hand. One  
day we'll catch up. -- Matthias









On Aug 27, 2008, at 7:19 AM, Shriram Krishnamurthi wrote:

> The intent is that you write test cases *before* you
> write your functions.  If you had done this, and your
> test cases covered your program, DrScheme would
> not complain at you.  Bad boy! (-:
>
> Shriram
>
> On Tue, Aug 26, 2008 at 11:39 PM, Grant Rettke <grettke at acm.org>  
> wrote:
>> Hi folks,
>>
>> In HTDP beginner language on problem 2.2.1, when I evaluate it,
>> DrScheme complains that "This program should be tested".
>>
>> is the intention that students start testing immediately, or we ill
>> add tests later on?
>>
>> I used check-expect for now.
>>
>> Best wishes,
>>
>> Grant
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