[Mockobjects-java-users] RE: Stubs vs. Mock Objects

[Vincent M. <vm...@oc...>]

Hi Andrew,

> -----Original Message-----
> From: Andrew Batishchev [mailto:aba...@ta...]
> Sent: 20 June 2002 18:14
> To: vm...@oc...
> Subject: Stubs vs. Mock Objects
> 
> Dear Vincent,
> The www.mockobjects.com site announces that you and Steve Freeman
> volunteered to share your vision of the subject.
> 
> Before you publish "a page explaining the differences between Mock
Objects
> and Stubs as it is largely misunderstood" at (which we are waiting
for,
> patiently)
> could you be so kind to give us some advice where we can find some
> resources
> 
> on this matter.
> 

I would suggest you read the PDF first that is available on the web
site.

> Can we draw a fine line between these two concepts?
> 
> Are mock objects extremely stupid and controlled by the unit test,
when
> stubs have some brains of their own?
> 

yes!

Mock objects = stupid empty placeholders. They just have setters and
getters and no logic. They are 100% controlled by the test case, which
calls the correct methods to put them in a desirable state, tell then to
throw exception when such method is called, etc.

Stubs = simple implementation that is replacing the real one. It is
simpler than the real one but still implementing the same logic (at
least the same interface _seen from the outside_). Eg, A method might
throw an exception if such file is not present on disk and if it is then
return it's value. A stub would have some logic and perform an "if" to
implement that logic. A more intelligent stub would be able to be
controlled by some configuration flag or would provide an API .. haha
this is when the 2 concepts start to merge

Let's say that a Mock Objects is like a stub for which you would have
100% of its logic been made parametrizable as an API that is controlled
by the test case.


> Is it possible for you to describe this difference in some condensed
form,
> just by a couple of sentences?
> 
> Sorry to bother you , but I am really desperate - I find myself in the
> middle of the new "To-Mock-or-not-to-Mock" holy war.

Either do in-container testing like Cactus or mock. Stubs is not a good
solution to me. It can be sometime for code that is not well written and
you want to see as a black box.

Cheers,
-Vincent

> 
> Just links to the resources would be splendid.
> 
> Thank you in advance
> Sincerely
> 
> Andrew Batishchev
> Software developer
> 
> Universal Tax Systems
> (706)624-4245 x 2265
> 
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