[Python-Dev] PEP: Consolidating names in the `unittest` module

[Nick Coghlan]

Stephen J. Turnbull wrote:
> Ben Finney writes:
> 
>  > Removal of ``assert*`` names
>  > ----------------------------
> 
>  > Arguments in favour of retaining only the ``assert*`` names:
>  > 
>  > * BDFL preference: The BDFL has stated [#vanrossum-1]_ a preference
>  >   for the ``assert*`` names.
>  > 
>  > * Precedent: The Python standard library currently uses the
>  >   ``assert*`` names by a roughly 8:1 majority over the ``fail*``
>  >   names. (Counting unit tests in the py3k tree at 2008-07-15
>  >   [#pitrou-1]_.)
>  > 
>  >   An ad-hoc sampling of other projects that use `unittest` also
>  >   demonstrates strong preference for use of the ``assert*`` names
>  >   [#bennetts-1]_.
>  > 
>  > * Positive admonition: The ``assert*`` names state the intent of how
>  >   the code under test *should* behave, while the ``fail*`` names are
>  >   phrased in terms of how the code *should not* behave.
> 
> FWIW, I think these are fairly stated.  So fairly that I'm surprised
> you haven't been persuaded!<wink>  Nitpick: the second point is not
> just "precedent", there's an economic reason there too.  Tests in the
> standard distribution which use the deprecated style will need to be
> converted.  Steven d'Aprano claims this is nontrivial (and thus error-
> prone) in some cases.  I haven't seen that claim denied, and it seems
> plausible to me.

I disagree with SdA's statement there: failUnless* maps directly to 
assert* and failIf* maps directly to assertNot*. There are no semantic 
changes whatsoever involved in that remapping, just a change in the 
method names.

Note that if the API is to be rationalised at all, my personal 
preference is to keep assert* and failIf* and get rid of their longer 
counterparts (failUnless* and assertNot*). Alternatively, ditch the 
binary assertion methods entirely, and use a check object to state those 
assertions:

   check(x).almost_equal(y) instead assertAlmostEqual(x, y)

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
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