From: James Mead <jamesmead44@...>
Date: 2006-11-28T18:27:27+09:00
Subject: Re: Mocha and ActiveRecord

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On 28/11/06, J. B. Rainsberger <jbrains762@gmail.com> wrote:
>
> Suppose I have an Order, which has_many OrderItems. Suppose I want to
> write a test that checks that when I ask the Order to do something, it
> asks its order items to do that something. I tried to do this like so:
>
> def test_delegates
>      order_items = []
>      3.times {
>          item = mock("order item", :do_something => nil)
>          order_items.push(item)
>      }
>
>      order = Order.new(:order_items => order_items)
>      order.do_something
> end
>
> This works with normal objects, but it seems ActiveRecord objects don't
> like someone passing them Mocha::Mock objects in their constructors.
> They check that the order items, in this case, are OrderItem objects.
>
> Is there something in ActiveRecord I can override to relax this
> behavior? I don't like having to create an OrderItem just to add a
> single stub or expectation.
>

What we tend to do in this case is stub the collection method itself i.e.
Order#order_items.

So you could do something like this...

def test_should_do_something_to_all_order_items
  order_items = Array.new(3) { mock('order item', :do_something => nil) }
  order = Order.new
  order.stubs(:order_items).returns(order_items)

  order.do_something
end

When I have a spare couple of hours I'll be releasing a new version of Mocha
that supports mocking of the is_a?. This will allow you to make this work
with ActiveRecord, but with the disadvantage that you are coupling your test
to the innards of ActiveRecord.

I hope that helps.
-- 
James.
http://blog.floehopper.org

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