From: olczyk@... (Thaddeus L Olczyk)
Date: 2001-12-12T01:23:13+09:00
Subject: [ruby-talk:28238] Re: John Roth dolt (  Re: A challenge to proponents of Unit Testing. )

On 11 Dec 2001 07:35:20 -0800, rbinder@rbsc.com (Bob Binder) wrote:

>Robert C. Martin <rmartin @ objectmentor . com> wrote in message news:<d62b1ukh61hal31708f4afr99ppg3utkde@4ax.com>...
>> On 10 Dec 2001 09:35:08 -0800, rbinder@rbsc.com (Bob Binder) wrote:
>> 
>> >Robert C. Martin <rmartin @ objectmentor . com> wrote in message news:<h2n41ucnnc8ipnseets4eess8rbqehkes6@4ax.com>...
>> >> On Sat, 08 Dec 2001 00:35:43 -0600, Robert C. Martin <rmartin @
>> >> objectmentor . com> wrote:
>> >> 
>> >> >On 7 Dec 2001 02:04:08 -0800, stephen.hill@motorola.com (Steve Hill)
>> >> >wrote:
>> >> >
>> >> >>What tests would you write for a function that takes 3 numbers (the
>> >> >>side lengths of a triangle) , and returns whether the triangle is
>> >> >>equilateral, scalene or isoceles.
>> >> >
>> >> >Set<int> sides; // data structure allows no duplicates.
>> >> >sides.add(a);
>> >> >sides.add(b);
>> >> >sides.add(c);
>> >> >return sides.length(); // 1 = equilateral, 2=isoceles, 3=scalene.
>>         ^^^^^^^^^--oops.
>> >> >
>> >> >What am I missing?
>> >
>> >In this example, wouldn't using an int set for the sides prevent
>> >representing any triangle with two or more equal lengths -- I think a
>> >bag would do the job. Assuming that your set would reject identical
>> >values, any test suite which did not include tests like 3,3,4 or 3,3,3
>> >would miss that bug.
>> 
>> The intent was to return a 1 for equilateral, 2 for isoceles, and 3
>> for scalene.  Representing the triangle was not part of the job.
>> 
>
>Ok, this is clever way to do the classification. But it seems to me
>this is only a fragment of the solution to the scope of the complete
>triangle problem, and conclusions drawn about testing this fragment
>versus testing a complete solution are skewed.
>
>Unless Set objects silently reject dups, the client code will have to
>have a catch block, which means part of the classification scheme
>resides in the client. The client will have to constrain lengths to 1
>or greater, and assure that the sides are constructable for the
>isoceles and scalene cases. If not, your code will claim that 1,1,10
>and 1,2,10 are sides of triangle, which they are not. As the
>implementation of these constraints is necessary for producing correct
>answers, it should be included in scope of the test suite.
>
You must also add a reporting mechanism for the violation of these
tests. And then you need to add more tests for the reporting
mechanism.