And_return question

Testing RSpec
1

Are these two forms theoretically functionally equivalent:

car = stub_model(Car)
Car.stub(:new).and_return(car)

Car.stub(:new).and_return(stub_model(Car))

I ask because I thought they were, but just hit something that suggests
they are not. I was originally using the first form, but then thought
I’d shorten it up a little (especially since nothing special is
happening in the stub_model call), so I changed it to form 2. But when I
did, I got an error:

NoMethodError in ‘Web::Agent::NelliesController get :new should assign
to @nelly’
You have a nil object when you didn’t expect it!
You might have expected an instance of ActiveRecord::Base.
The error occurred while evaluating nil.id=
/Library/Ruby/Gems/1.8/gems/activesupport-2.3.5/lib/active_support/core_ext/object/misc.rb:39:in
`returning’
./spec/controllers/web/agent/nellies_controller_spec.rb:140:
script/spec:10:

Line 140 of the spec was where I was using form 2. I change it back to
form 1 and the error went away.

Thoughts?

Peace,
Phillip

2

On May 6, 2010, at 10:09 AM, Phillip K. wrote:

Line 140 of the spec was where I was using form 2. I change it back to form 1 and the error went away.

Thoughts?

stub_model(Car) invokes Car.new. The call to Car.stub(:new) overrides
new() before stub_model(Car) is evaluated. Make sense?

3

On 2010-05-06 9:51 PM, David C. wrote:

script/spec:10:

Line 140 of the spec was where I was using form 2. I change it back to form 1 and the error went away.

Thoughts?
stub_model(Car) invokes Car.new. The call to Car.stub(:new) overrides new() before stub_model(Car) is evaluated. Make sense?

Thank, David!

Yes, it makes perfect sense. I have use form 2 a few times before
without any difficulty, and hadn’t really thought about it. In this
particular case, though, I was doing something just slightly different
that happened to expose this very important detail.

Peace,
Phillip