Re: spec'ing calls to super (or other Ruby keywords)

Funny, I mostly like writing RSpec specs for Rails, aside from the fact
that it sometimes takes me a while to figure out exactly how and what I
need to write to specify what I want to specify.

In any case, I agree that the spec should specify what the method
achieves, not the fact that the method calls super.

Al

----- Original Message ----
From: Scott T. [email protected]
To: rspec-users [email protected]
Sent: Saturday, May 3, 2008 1:51:51 PM
Subject: Re: [rspec-users] spec’ing calls to super (or other Ruby
keywords)

On May 3, 2008, at 11:09 AM, Al Chou wrote:

In the particular case of super, another approach, though perhaps not
using the spec framework, would be to assert (a la Test::Unit) that your
class is a subclass of the intended superclass. To be truly anal, also
assert that the superclass has a method with the same name as the
subclass’s method of interest and that the subclass has that method,
too. But all this seems deeply into the xUnit world, and far from the
BDD way.

Al

The truth is that you shouldn’t be spec’ing calls to the super “method”,
but rather the behaviour of super. One quick way to do this is as so:

[BaseClass, Subclass].each { |klass|
it “should do whatever super does” do

klass.new.foo_bar.should == :baz

end
end

Your original example is a little trickier, because you didn’t write the
base class, and you probably aren’t going to spec it out. There’s
obviously great complexity in that call to super. Now you know why none
of us like writing specs against rails apps.

Scott

----- Original Message ----
From: John D. Hume [email protected]
To: rspec-users [email protected]
Sent: Saturday, May 3, 2008 7:49:11 AM
Subject: Re: [rspec-users] spec’ing calls to super (or other Ruby
keywords)

I believe calls to super are sufficiently internal to the Ruby
interpreter that a mocking framework can’t intercept them without doing
separate implementations for separate Ruby interpreters (and likely even
separate versions). I could be wrong, but even so I’d recommend a
different approach.

If your need is really as simple as your example, what you have is just
a method that has to get two things done: the base save and one
additional call. You can write one (or more) example for each of those
two things without your spec knowing that one of those things gets done
by calling super. (You might object that by spec’ing the base #save
behavior you’re spec’ing the framework. I’d say you’re USING the
framework to spec something your code does. To be clear, I’m not
suggesting you spec every detail of what save does: just something to
make sure the record actually lands in the db.)

(Sidebar: Keep in mind the return value if you’re really overriding
#save like that.)

If you’re dead set on spec’ing that the super method gets called, there
are a couple of hideous ways of doing it that will leak out of your
example. Namely, you can (in your spec) redefine the method in the
superclass and verify it gets called or (also in your spec, and this
one’s a little less leaky) have the class under test include a module
that defines the same method and verify it gets called. Don’t do either
of those though (unless it’s just to prove to yourself that they’re
possible).

-hume.

On Fri, May 2, 2008 at 5:17 PM, Matt McNeil [email protected] wrote:

Hi there,

How does one spec an invocation of a Ruby keyword, such as super in this
case?

class User < ActiveResource::Base

faking the ActiveRecord before/after_save observers

def save
super
UserMailer.deliver_activation(self) if recently_activated?
end
end

Does the solution look anything like the following?

describe User do
describe ‘#save’ do
it “should call save on the parent class” do
# something.should_receive(:something)
@user.save
end
end
end

Any thoughts?

Thanks much,
Matt

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