[rspec-users] Testing that named_scope is defined

David Chelimsky dchelimsky at gmail.com
Tue May 13 22:50:58 EDT 2008

Oi Helder,

On May 13, 2008, at 9:14 PM, Helder Ribeiro wrote:

> On Tue, May 13, 2008 at 9:20 PM, Pat Maddox <pergesu at gmail.com> wrote:
>> I wonder why OP doesn't create two records, call #most_recent, and
>> verify that the record returned is the one with the larger timestamp.
> I'm sorry about the confusion here. Your idea sounds indeed better
> (I'll explain below).
>> If the code is "not yours" (and I think you ought to clarify what you
>> mean by that), then you should be testing it at a higher level  
>> instead
>> of directly.
> As I said, I'm not very familiar with specs and stuff, and I've read
> repeatedly on this list and other places that one should only test
> one's own code. That is, if you declare a has_many association, you
> shouldn't test that the methods actually return the proper model
> objects, etc., because that would be testing ActiveRecord. In that
> same spirit, I thought I shouldn't test that a named_scope does what
> it's supposed to, only that it is declared (because that one line is
> all I wrote myself).

You're thinking of this backwards. You are trying to test that you're  
using a specific method rather than expecting a behaviour. Specs are  
about behaviour. You're trying to backfill them against implementation.

The behaviour you expect is to find the most recent posts, so that's  
what the example should expect. The fact that you're implementing that  
(which should happen after you write the example, not before) with  
named_scope instead of defining a method is an implementation detail.  
If you decide later that, for whatever reason, you want to change the  
implementation to a defined method, this example will still pass - or  
fail if you do the wrong thing. That's the whole point for executable  
examples. They encourage you to write the code you need and only the  
code you need, and then later they let you know whether changes you  
make to implementation preserve the behaviour that you are expecting.

That all make sense?


ps - eu acho que você é brasileiro ou português por causa do seu nome  
- né?

> But I guess I got a bit carried away, as in that declaration there is
> stuff besides the declaration itself, namely, the bit specifying the
> order. So it would be better to test for that, rather than just
> testing if it was declared or not.
> Thanks a lot for your help :)
>> Pat
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> -- 
> Helder Ribeiro
> Embedded Systems
> http://profusion.mobi
> "If I have not seen as far as others, it is because giants were
> standing on my shoulders" -- Jeff Goll
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