testing -- what to do for testing code with behaviour dependant upon which files exist?

[Brian van den Broek]

> "Brian van den Broek" <bvande at po-box.mcgill.ca> wrote in message 
> news:424F00D5.9020205 at po-box.mcgill.ca...
> 
>>Hi all,
>>
>>I'm just starting to employ unit testing (I'm using doctest), and I am
>>uncertain how to handle writing tests where the behaviour being tested is 
>>dependant on whether certain file paths point to actual files.

Hi all,

I had a busy weekend after posting, so didn't get a chance to 
follow-up until now. Thanks to all who responded.

Python's my first real language, and I am a mere hobbyist, so the 
suggestions for search terms provided by Terry (and implicitly by 
Andre who suggested a mock strategy) are most welcome! Sometimes the 
hardest part of googling is knowing what terms to search for.

Grig suggested the tempfile module; I had rejected that initially, as 
the code I am testing displays an error message containing the bad 
file path, so I thought I needed to know the path name at time of 
coding the tests. But, I've since learned that doctest can be made to 
consider only leading portions of a line's content. So, this might 
well work for me. Thanks for reminding me of the approach.

Jeremy suggested using a directory name akin to 
"C:\onlyanidiotwouldhavethisdirecotrynameonadrive". That is what I had 
settled on before I posted. Somehow it feels unhappy and inelegant. 
But, I'm a bit less uncomfortable with it seeing that others have done 
so, too.

Anyway, thanks again for the suggestions :-)  Best to all,

Brian vdB