unittest & setup

[Jonathan Haddad-3]

Maybe I'm doing something wrong here, definitely not the most experienced unit tester. 

I've got a class, in the constructor it loads a CSV file from disc.  I'd like only 1 instance of the class to be instantiated.  However, when running multiple unit tests, multiple instances of the class are created.  What's the best way for me to avoid this?  It takes about a few seconds to load the CSV file.
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Jonathan Haddad
http://www.rustyrazorblade.com


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[Gabriel Genellina-7]

En Wed, 04 Nov 2009 01:02:24 -0300, Jonathan Haddad <jon@...>  
escribió:

> I've got a class, in the constructor it loads a CSV file from disc.  I'd
> like only 1 instance of the class to be instantiated.  However, when  
> running
> multiple unit tests, multiple instances of the class are created.  What's
> the best way for me to avoid this?  It takes about a few seconds to load  
> the
> CSV file.

Use a factory function:

_instance = None
def createFoo(parameters):
   if _instance is None:
     _instance = Foo(parameters)
   return _instance

and replace all occurrences of Foo(parameters) with createFoo(parameters).  
For new-style classes, you may override the __new__ method instead.

Perhaps I didn't understand your problem correctly because this is  
unrelated to unit testing...

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Gabriel Genellina

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[Joe Riopel]

On Tue, Nov 3, 2009 at 11:02 PM, Jonathan Haddad <jon@...> wrote:
> I've got a class, in the constructor it loads a CSV file from disc.  I'd
> like only 1 instance of the class to be instantiated.  However, when running
> multiple unit tests, multiple instances of the class are created.  What's
> the best way for me to avoid this?  It takes about a few seconds to load the
> CSV file.

This post that might be worth reading, as it relates to testing with
singletons.

http://misko.hevery.com/2008/08/17/singletons-are-pathological-liars/

As is this

http://misko.hevery.com/code-reviewers-guide/
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