Re: [Pyunit-interest] Feature Request: Cleanup Registry

[Steve P. <ste...@ya...>]

Hi Jim,

Sorry for the slow response.

Interesting suggestion. I wonder about a couple of things.

Firstly, not every test would require every cleanup function to be
called, so calling every function after every test seems a high
price to pay for convenience. Imagine running 10,000 tests,
where each block of 100 requires a single (but different) clean-up
function: that's 1,000,000 cleanup function invocations instead
of 10,000.

Secondly, I'm nervous about the notion of adding clean-up functions
to the clean-up registry from 'outside' testing code, as in the
example you provided. What if the test module is imported multiple
times, e.g. by the unittest GUI? -- then, clean-up functions might
be registered multiple times, presumably in global variables in
the unittest module.

Cleaning-up of component registries is to be done after every
Zope test, as I understand things. In that case, I'd think
a common base class for your Zope test cases is in order, with a
standardised 'tearDown()' that all subclasses should call if they
also implement a 'tearDown()' method. This is a safer solution, in
my opinion.

Or am I missing something?

Very best wishes,

-Steve


Jim Fulton wrote:
> Problem
> 
>   the Zope 3 project is making extensive use of PyUnit.  Zope 3 unit
>   tests often have to register components with various component
>   registries. These registrations need to be torn down after each
>   test. This became very tedious. For this reason, we've implemented a
>   cleanup registry. Any stateful global objects, like component
>   registries register functions with this cleanup registry. Test
>   classes provide tearDown methods that call a method on the cleanup
>   registry, which calls all the registered functions.  This is an
>   extremely useful pattern that might be beneficial to other
>   projects. Further, it would be nice if test classes didn't have to
>   provide a tear-down method that just called the cleanup registry (or
>   mix-in a class that provided such a tearDown.
> 
> Proposal
> 
>   Add a cleanup registry to the unittest module.  The unittest module
>   would provide an additional function, addCleanUp, which takes a
>   callable object to be called without arguments after running each
>   unit test. After each test, and after running the test class's
>   tearDown method, each registered cleanup callable will be called.
> 
>   Suppose there was an application module with a global dictionary
>   that was manipulated by application routines:
> 
>      TheData = {}
> 
>   The module would register the clear method of this dictionary with
>   unittest.addCleanUp to make sure the dictionary was reinitialized
>   after each test:
> 
>      import unittest
>      unittest.addCleanUp(TheData.clear)
> 
> I'd be happy to provide a patch.
> 
> Jim