[Zope3-dev] Re: testing interfaces / Cookbook

[Jim Fulton]

Philipp von Weitershausen wrote:
> Yuppie,
> 
>> The Cookbook uses this example
>>
>>     def test_interface(self):
>>         self.assert_(IMessageBoard.isImplementedBy(
>>             self.makeTestObject()))
>>
>> Does it make sense to use providedBy (fka isImplementedBy) in unittests? 
> 
> 
> isImplementedBy is deprecated. providedBy should be used when checking 
> whether an object *provides* an interface. implementedBy should be used 
> when checking whether a class *implements* an interface.

Yup

>> Wouldn't it be better to verify the interface?
> 
> 
> I guess so, though I feel that makes interfaces quite a serious 
> contract. Oh well, I guess they *are* a contract, and checking that in 
> unit tests couldn't hurt.

In tests, you generally want verify.  Testing (or in some sort of
development tool) is the only time to use verify.

> However, sometimes you're just interested whether the object you get 
> from some machinery implements an interface, i.e. promises a contract. 
> That often is enough.

At "run time" you want to use implementedBy or providedBy.  They are
much faster than verify.

Jim


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