Re: HOWTO: Writing Perl6 Tests (was: Project Start: Section 1)

Dave Whipp wrote:

> Richard Nuttall wrote:
>
>> Writing a complete test suite really also needs reasonable knowledge
>> of how the internals are written in order to understand the kinds of
>> tests that are likely to provoke errors. (More thoughts on this if 
>> requested).
>
[...]

> Consider item 0. Do we need to test C<reverse(undef)>? The answer is 
> probably "no": conversion of undef to an empty lsit is a property of 
> the  list context in the caller. We tested that as part of our 
> compehensive set of arglist evaluations. The reverse function never 
> sees the undef, so we don't need to test it.

This is an example of an awareness of implementation leading to better 
knowledge about what areas are worth testing.

In a previous life, I worked as part of a team (implementing Expert 
Systems in VAX Pascal actually), and we had one person whose sole aim in 
life was to design and build test cases. In many cases his complete lack 
of knowledge of implementation detail was good because he thought up all 
sorts of tests that were useful because he wasn't as close to the trees 
as we were, in other cases some of the tests didn't exercise any new 
functionality because in the itnernals, seemingly different cases were 
implmented using the same functionality.

R.