[TIP] RFC: Post-assertRaises assertions WAS: ANN: unittest2 0.4.0 Release

[Michael Foord]

On 09/04/2010 17:34, Olemis Lang wrote:
> On Fri, Apr 9, 2010 at 11:27 AM, Michael Foord
> <fuzzyman at voidspace.org.uk>  wrote:
>    
>> On 09/04/2010 14:55, Olemis Lang wrote:
>>      
>>> On Fri, Apr 9, 2010 at 8:15 AM, Michael Foord<fuzzyman at voidspace.org.uk>
>>>   wrote:
>>>
>>>        
>>>> On 09/04/2010 14:10, Olemis Lang wrote:
>>>>
>>>>          
>>>>> On Thu, Apr 8, 2010 at 5:42 PM, Michael Foord<michael at voidspace.org.uk>
>>>>>   wrote:
>>>>>
>>>>>
>>>>>            
>>>>>> Hello all,
>>>>>>
>>>>>>              
>>>>> :o)
>>>>>
>>>>>
>>>>>            
>>>>>> I'm pleased to announce the release of version 0.4.0 of unittest2.
>>>>>>
>>>>>>              
>>>>> [...]
>>>>>
>>>>>
>>>>>            
>>>>>> For full details of all the new features, see my blog entry:
>>>>>>
>>>>>> *
>>>>>>
>>>>>> http://www.voidspace.org.uk/python/weblog/arch_d7_2010_04_03.shtml#e1171
>>>>>>
>>>>>>
>>>>>>              
>>>>> I wanted to know if you have considered support for writing assertions
>>>>> targeting the exception object been raised . In my experience that is
>>>>> very helpful when testing some kind of systems. For instance, in Trac
>>>>> XmlRpcPlugin (<=0.1.6, current trunk ;o) you can find many tests
>>>>> (actually all TCs checking for error conditions ;o) like this
>>>>>
>>>>>            
>>>> Did you check the docs?
>>>>
>>>>
>>>>          
>>> Good RTFM , thnx . Should be something like this (isn't it ?):
>>>
>>> {{{
>>> #!python
>>>
>>> # blah blah blah ...
>>>     def test_wrong_argspec(self):
>>>         ctx = self.assertRaises(xmlrpclib.Fault)
>>>         with ctx :
>>>             self.admin.system.listMethods("hello")
>>>             self.fail("Oops. Wrong argspec accepted???")
>>>         e = ctx.exception
>>>         self.assertEquals(1, e.faultCode)
>>>         self.assertTrue("listMethods() takes exactly 2 arguments" \
>>>                                     in e.faultString)
>>> }}}
>>>
>>> However I'm also interested in how it works (backwards compatibility
>>> ;o) for versions with no support for context managers (AFAIK, there
>>> are still people using Trac on Py 2.4 ;o)
>>>
>>> Is it possible to consider returning the exception object when the
>>> ctxman is not returned ?
>>>
>>>        
>> No, sorry. There is no need for this in Python 2.7 (which has context
>> managers) and I'm not going to put incompatible changes into unittest2.
>>
>>      
> FWIW, since assertRaises doesn't return anything then all code using
> that method today would be backwards compatible (they all ignore its
> return value which is always None ;o) ... I know you already said *NO*
> .
>
>    

Code that uses that feature would be incompatible with unittest in 
Python 2.7 / 3.2 - that is what I mean. unittest2 is just a backport, so 
I want to avoid differences like this. I expect that as unittest grows 
in Python 3.2 there will be features in unittest2 not in 2.7 - but 
unittest2 will still just be a backport.

Michael

> back to my cave ...
>
>    
>> You can still use the alternative version of assertRaises if you *just* want
>> to check the exception message.
>>
>>      
> ok
>
>    


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http://www.voidspace.org.uk/blog

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