[Python-ideas] ABC: what about the method arguments ?

Terry Reedy tjreedy at udel.edu
Fri Sep 24 18:20:49 CEST 2010

On 9/24/2010 10:17 AM, Daniel Stutzbach wrote:
> On Thu, Sep 23, 2010 at 7:24 PM, Terry Reedy
> <tjreedy at udel.edu
> <mailto:tjreedy at udel.edu>> wrote:
>     Can this work? Split the current test suite for a concrete class
>     that implements one of the ABCs into concrete-specific and
>     ABC-general portions, with the abstract part parameterized by
>     concrete class.
>     For instance, split test/test_dict.py into test_dict.py and
>     test_Mapping.py, where the latter has all tests that test compliance
>     with the Mapping ABC (or whatever it is called) and the former keeps
>     all the dict-specific extension tests. Rewrite test_Mapping so it is
>     not dict specific, so one could write something like

Reading the responses, I realized that I am already doing a simplified 
version of my suggestion for functions rather than classes. For didactic 
purposes, I am writing multiple implementations of multiple abstract 
functions. I embody a test for a particular function in an iterable of 
input-output pairs (where the 'output' can also be an exception class). 
I use that with a custom super test function that tests one or more 
callables against the pairs. It works great and it is easy to add 
another implementation or more pairs.

> As a heavy user of the ABCs in the collections module, that would be
> awesome. :-)  It would make my life a lot easier when I'm writing tests
> to go along with an ABC-derived class.  I have 8 such classes on PyPi
> (heapdict.heapdict and blist.*), plus more in private repositories.
> There is some code vaguely along those lines in the existing unit tests.
>   For example, Lib/test/seq_tests.py contains tests common to sequences.
>   However, that was written before collections.Sequence came along and
> the pre-2.6 definition of "sequence" only loosely correlates with a
> collections.Sequence.

Well, pick one existing test file, revise and extend and perhaps split, 
start a tracker issue with proposed patch, get comments, and perhaps 
commit it. If you do, add terry.reedy as nosy.

Terry Jan Reedy

More information about the Python-ideas mailing list