accept two optional args in Rack::Session::Abstract::SessionHash#fetch

[hfaulds]

I got bitten by a bug in rails that lead me to this class. They inherit from Rack::Session::Abstract::SessionHash for some session hash classes relating to forgery protection (https://github.com/rails/rails/blob/e7feaff70f13b56a0507e9f4dfaf3ebc361cb8e6/actionpack/lib/action_controller/metal/request_forgery_protection.rb#L135). Whilst in the normal session hash they have implemented fetch with two optional arguments (https://github.com/rails/rails/blob/e7feaff70f13b56a0507e9f4dfaf3ebc361cb8e6/actionpack/lib/action_dispatch/request/session.rb#L133-L140). They also have a separate session hash class for testing which implements the two optional args for fetch.

I had some shared code between controllers called session.fetch with the default argument, this caused exceptions for controllers that used forgery protection it also didn't exception in the tests for these controllers.

Whilst this is a bug in rails it seems like this class in rack was the right place to fix it and properly mimic the behaviour of Ruby's Hash.

I would have added another spec but it outputs the warning rack/lib/rack/session/abstract/id.rb:66: warning: block supersedes default value argument in the middle of the test suite. Given the current tests for this class it seemed better to just not include it than to hide the warning.

it "returns the correct value using a block and default" do
  assert_equal 'missing', hash.fetch(:missing, :default) { |el| el.to_s }
end

[ioquatix]

It looks like this has been merged. Thanks for your contribution.