Mocha and ActiveRecord

Ruby
1

Everyone:

I’ve been using Mocha, which I rather love, to help me test-drive some
Rails code. I’ve run up against something a little clunky, and I’m
hoping one of you can help me out.

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.

Thanks for your help.

2

On 28/11/06, J. B. Rainsberger [email protected] wrote:

 }

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.

3

BTW - it’s probably better to use the Mocha mailing list -
http://rubyforge.org/mailman/listinfo/mocha-developer

4

James M. wrote:

     order_items.push(item)

Is there something in ActiveRecord I can override to relax this
order_items = Array.new(3) { mock(‘order item’, :do_something => nil) }
test
to the innards of ActiveRecord.

I hope that helps.

That’s not bad. I think I’d rather stub the collection than sorry about
is_a?. I’ll give this a shot and let you know how it goes.

Thank you, James.