Rails 3, RSpec 2.5: Using should_receive or stub_chain with named scopes

问题

I use Rails 3.0.4 and RSpec 2.5. In my controllers I use named scopes heavily, for example

   @collection = GuestbookEntry.nonreplies.bydate.inclusive.paginate(
       :page => params[:page], :conditions => { ... })

In my tests, I want to be able to mock the result of such a query, not the wording. I do not think it makes sense to do something like

   GuestbookEntry.stub_chain(:nonreplies, :bydate, ...).and_return(...)

because this test will fail the moment I decide to reorder the named scopes.

With Rails 2.3 and RSpec 1.x, this worked fine: I could write

   GuestbookEntry.should_receive(:find).with(:all, :conditions => { ... })

and the above call would be caught and correctly handled. However, with Rails 3, for some reason this does not work any more.

Why? How do I set expectations or stubs on the result of nested scopes? Since everything in Rails 3's ActiveModel is a named scope (thanks to ARel), this must be possible somehow, or tests would indeed be very brittle.

Thanks!

Update: See also issue report on GitHub.

回答1:

This problem has bugged me for a while too!

I believe the reason the behaviour is different from Rails 2 is because the query is no longer being performed during the variable assignment in the controller. Instead, it's lazy-loaded as required.

I agree with Mark Wilden that it's better to wrap all of these scopes in a larger scope and spec that in your model. This scope clearly has a specific function, so just as one would spec the behaviour of a method which calls several other methods, you would spec the behaviour of a scope that joins several other scopes.

回答2:

I would wrap such a complicated query in its own scope, and stub that.

来源：https://stackoverflow.com/questions/5251536/rails-3-rspec-2-5-using-should-receive-or-stub-chain-with-named-scopes