[Python-Dev] unit tests for error messages

[R. David Murray]

On Wed, 19 Mar 2014 20:32:38 +0100, Georg Brandl <g.brandl at gmx.net> wrote:
> Am 19.03.2014 19:55, schrieb Antoine Pitrou:
> > On Wed, 19 Mar 2014 10:53:31 -0700
> > Ethan Furman <ethan at stoneleaf.us> wrote:
> > 
> >> I just made a change to some error messages [1] (really, just one):
> >> 
> >> old behavior:
> >> 
> >>    '%o' % 3.14
> >>    'float' object cannot be interpreted as an integer
> >> 
> >> new behavior:
> >> 
> >>    '%o' % 3.14
> >>    %o format: an integer is required, not float
> >> 
> >> Would we normally add a test for that?
> > 
> > Depends if you're fearing a regression.
> 
> If he fears regressions in error messages, he shouldn't be changing them
> in the first place :)

In this type of situation I will often write a unit test that makes
sure that the piece of information I just added to the message is really
in the message ('%o', in this case), using assertRaisesRegex.  I don't
think it is required, but I like to do it, because it would indeed be
a regression if that information stopped appearing in the message.

--David