On 7 Jun 2010, at 15:56, Ben Butler-Cole wrote:
> On 7 June 2010 15:25, Matt Wynne <m...@mattwynne.net> wrote:
>
> Have you seen and_yield? I can't quite get my head around what you're trying
> to do, but it might help anyway
>
> Thank you, I have. My understanding is that #and_yield has much the same use
> as #and_return (in its non-bastardized-by-me-form). That is, you specify it
> in order to make the mocked-out collaborator behave enough like the real
> collaborator that the object-under-test can work properly.
>
> I'll try to explain what I'm aiming for more comprehensibly.
>
> If I my object-under-test calls a method with a parameter, I can make
> assertions against the values passed. The simplest is equality:
>
> foo.should_receive(:bar).with(6)
>
> The corresponding code in the object-under-test is
>
> foo.bar(6)
>
> and the real code for the collaborator is something like:
>
> class Foo
> def bar(x)
> // ...
> end
> end
>
> Now the collaborator in my case doesn't take a parameter, it takes a block:
>
> class Foo2
> def bar2(&block)
> // ...
> end
> end
>
> and the object-under-test passes in a block which is called later for its
> return value:
>
> foo2.bar2 { 6 }
>
> (The real block doesn't return a constant, obviously. It returns something
> which needs to be evaluated lazily because its dependencies don't exist yet.)
>
> I want to test that the block passed in is the block that I expect. Something
> like (in an imaginary world):
>
> foo2.should_receive(:foo2).with(block(yielding(6)))
>
> (In fact, in my case I can't just assert equality on the return value from
> the block. I'm actually going to test its type.)
>
> The corresponding test using my obscene #and_return hack looks like this:
>
> foo2.should_receive(:foo2).and_return { |block| block.call.should ==6 }
>
> But this doesn't scale to multiple calls to #foo2 in the object under test
> because RSpec (understandably) matches its expectations against invocations
> based on method name and argument matchers.
I'm still not quite clear what you're trying to achieve. Do you want to assert
that a specific block is passed to the collaborator, or do you want to assert
that any old block with a particular behaviour is passed to the collaborator?
If it's the former, you can test it by creating a test double for the block,
and asserting that it's passed to the collaborator, like this:
http://gist.github.com/428801
Does that help?
>
> -Ben
>
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