[Zope-dev] Re: relocating Zope 2 core interfaces - a proposal

[Philipp von Weitershausen]

Tres Seaver wrote:
>>Your unit test should exercise the whole API promised by an
>>implementation anyway, so often an explicit interface check is redudant
>>(of course, it can't hurt). verifyClass() per se isn't bad, it's in fact
>>a useful indicator, but having that it as a *sole* measure whether a
>>class fulfills an interface or not is not sufficient (plus, in many Zope
>>cases, verifyObject is better because attributes may only be initialized
>>in __init__).
>>
>>The point why I think it's YAGNI is that we know the Zope 2
>>implementations do implement the interfaces. After all, I derived the
>>interfaces from the implementations by gutting out the code. And it's
>>unlikely they'll change (although I might be wrong on this one, in which
>>case you win :)).
> 
> When writing "test-first", I often start with only the 'verifyClass'
> test, and an empty interface.  Then as I flesh out the interface, the
> test fails, reminding me to add the method / attribute.  Yes, you still
> need tests for the semantics, but the conformance test is still
> valuable, because it "tests the tests" (an extra safety belt).

Fair enough. Note the "extra": it shouldn't be your only one.

Philipp