Rails - Apr 2005 - Mock setup

Hi all,

	I''m trying to use either a mock or an extension to ActionMailer to 
effectively add an error injection mechanism for some unit tests. 
Currently, I have a config variable that I turn on and off in the unit 
test. If this flag is on, the ActionMailer model raises an exception. 
Obviously, this is a little ugly.

	What I''d like to effectively do is change ActionMailer to have the 
following:

module ActionMailer
	class Base
		@@inject_one_error = false
		cattr_accessor :inject_one_error

		class << self
			private
			def perform_delivery_test
				if inject_one_error
					Base::inject_one_error = false
					raise "Failed to send email" if raise_delivery_errors
				else
					deliveries << mail
				end
			end
		end
	end
end

The, in my unit test, I have something like:

ActionMailer::base.inject_one_error = true
post :action, params => { "blah "}

The :action call Notifier::deliver_some_mail(), where Notifier is my 
application specific model derived from ActionMailer::Base. The :action 
has the exception handling code, so I just verify some stuff about the 
state of the controller after that.

Now, I''ve tried redefining this method in ActionMailer::Base::self via 
module_eval in my notifier.rb model file. But this doesn''t work for 
testing when running rake, I believe because of load order for modules 
(but I haven''t figured out how to do it correctly yet).

So, has anyone done something like this, or set up a mock object for 
testing? I''d really like to hook into ActionMailer::Base::self, or the 
functional equivalent, so I only have to implement a small amount of 
code instead of mucking with my Notifier class.

Thanks,
Joe

Well, I found the problem(s) and the solution was close to what some 
suggestions had been. Here''s what I wound up doing.

First, mock files should have the same name as the model they are 
replacing from app/models. So, in my case, I needed 
test/mocks/test/notifier.rb instead of test/mocks/test/test_mailer.rb.

Second, the mock file needs to have "require models/[model]" first 
(even though I''m only making changes to ActionMailer::Base, not the 
Notifier class derived from it).

Then, in this file, I have:

ActionMailer::Base.class_eval {
   @@inject_error = false
   cattr_accessor :inject_error

   @@inject_one_error = false
   cattr_accessor :inject_one_error

   class << self
     private
     def perform_delivery_test(mail)
       if inject_error or inject_one_error
         ActionMailer::Base::inject_one_error = false
         raise "Failed to send email" if raise_delivery_errors
       else
         deliveries << mail
       end
     end
   end
}

Now, in my test controller, I can reference the ActionMailer::Base 
class instead of the Notifier (though there''s no reason this is really 
necessary), and the Notifier class is referenced in the controller 
itself, but now has error injection.

If this is useful for anyone, I''ll have it up in the salted-login 
project on RubyForge sometime later today or tomorrow (it''ll be in 
version 1.0.5 or later).

Joe

On Apr 18, 2005, at 4:30 PM, Joseph Hosteny wrote:
> Hi all,
>
> 	I''m trying to use either a mock or an extension to ActionMailer
to
> effectively add an error injection mechanism for some unit tests. 
> Currently, I have a config variable that I turn on and off in the unit 
> test. If this flag is on, the ActionMailer model raises an exception. 
> Obviously, this is a little ugly.
>
> 	What I''d like to effectively do is change ActionMailer to have
the
> following:
>
> module ActionMailer
> 	class Base
> 		@@inject_one_error = false
> 		cattr_accessor :inject_one_error
>
> 		class << self
> 			private
> 			def perform_delivery_test
> 				if inject_one_error
> 					Base::inject_one_error = false
> 					raise "Failed to send email" if raise_delivery_errors
> 				else
> 					deliveries << mail
> 				end
> 			end
> 		end
> 	end
> end
>
> The, in my unit test, I have something like:
>
> ActionMailer::base.inject_one_error = true
> post :action, params => { "blah "}
>
> The :action call Notifier::deliver_some_mail(), where Notifier is my 
> application specific model derived from ActionMailer::Base. The 
> :action has the exception handling code, so I just verify some stuff 
> about the state of the controller after that.
>
> Now, I''ve tried redefining this method in ActionMailer::Base::self
via
> module_eval in my notifier.rb model file. But this doesn''t work
for
> testing when running rake, I believe because of load order for modules 
> (but I haven''t figured out how to do it correctly yet).
>
> So, has anyone done something like this, or set up a mock object for 
> testing? I''d really like to hook into ActionMailer::Base::self, or
the
> functional equivalent, so I only have to implement a small amount of 
> code instead of mucking with my Notifier class.
>
> Thanks,
> Joe
>
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