[ANN] Metatest 0.1.0

[Jonathan Fine]

Ben Finney wrote:
> Jonathan Fine <jfine at pytex.org> writes:
> 
>>Here's how to write some tests using Metatest. We can think of the
>>tests as an executable specification.
>>
>>    from metatest.py.mymod import plus, Point
>>
>>    # Function plus adds two numbers.
>>    plus(2, 2) == 4
>>    plus(2, '', _ex=TypeError)
> 
> This second example seems counterintuitive. Is '_ex' part of the
> public interface? If so, why does it follow the convention for "not
> part of the public interface" (i.e. it is named with an underscore)?

Hello Ben

(Well, I'm glad you seem to find the first example intuitive.)

No, the function we are testing here is
     def plus(a, b):
         return a + b

However, the line
    plus(2, '', _ex=TypeError)
refers only indirectly to the function plus, to be imported from mymod.

Read again the line
    from metatest.py.mymod import plus, Point

We do some metapath magic and some __method__ tricks to ensure that here 
plus is what I have called a 'stub object', although 'unknown' would be 
a better term.  See
    http://metatest.sourceforge.net/doc/pyconuk2007/metatest.html#slide11
    http://www.python.org/dev/peps/pep-0302/

The line
      plus(2, '', _ex=TypeError)
causes something to be recorded, and when the test is run the _ex 
argument is filtered off, and the remaining arguments passed to the plus 
function, as imported from mymod.

This is done by the function split_kwargs in the module
http://metatest.cvs.sourceforge.net/metatest/metatest/py/metatest/player.py?view=markup

Hope this helps.  If not, maybe try downloading and running it.

Finally, if you can think of a better way of saying, in Python, "The 
function call plus(2, '') raises a TypeError", please let me know, and 
I'll consider using it in the next version of Metatest.

-- 
Jonathan