Fixes an issue where cache sweepers with only after filters would have no controller object

[jeroenj]

It would raise undefined method controller_name for nil while trying to reach controllers where the sweeper was defined.

I do not have tests for this yet...

[spastorino]

Everything should be tested ;), we will wait for tests in order to review it.

[jeroenj]

It appears that the cache_sweeper isn't tested, or am I overlooking something?

[dmathieu]

It is tested.
https://github.com/rails/rails/blob/master/actionpack/test/controller/filters_test.rb#L500-531

[jeroenj]

Right. Ignore my previous comment... :)

[jeroenj]

Since I'm not sure if this is the best test, I didn't commit it yet but here it is:

def test_after_method_of_sweeper_should_always_return_nil
  sweeper = ActionController::Caching::Sweeper.send(:new)
  assert_nil sweeper.after(TestController.new)
end

If you run the test snippet above, and you aren't using the fix in my previous commit, you'll get the following exception:

NoMethodError: undefined method `controller_name' for nil:NilClass

You can reproduce this by only using an after filter in a cache sweeper. If you don't define a before filter, it will never set self.controller in the sweeper, which causes it to crash in the private callback method in the Sweeper class.

[dmathieu]

It seems fine to me.

[spastorino]

I guess we should add this to 3-1-stable too, can you provide a backport?

[jeroenj]

I encountered this issue in Rails 3.0.x actually. As far as I can see it's compatible with rails-3.0, rails-3-1 and master.

[spastorino]

provide a backport to 3-1-stable so, thanks :)