[Routes][Gem] assert can't see route

Hello,

I have problem with routes in my gem. I have this example code for
adding routes :
module ActionDispatch::Routing
    class Mapper
       def gallery_for
        match "/gallery/get/:id" => "gallery/
view#get", :as=>:gallery_galleries_by_user_id
       end
    end
end
And I'm trying to test it by :
class RoutestTest < ActionController::TestCase
  test 'map gallery get' do
    puts Rails.application.routes.routes
    assert_routing '/gallery/get/1', :controller => "gallery/
view", :action => "get"
  end
end
I added puts Rails.application.routes.routes to see routes. Then I try
to test it I get :
   /gallery/get/:id(.:format) {:controller=>"gallery/
view", :action=>"get"}
E

Error:
test_map_gallery_get(RoutestTest):
ActionController::RoutingError: No route matches "/gallery/get/1"
What I'm doing wrog or is it any rails bug ?