potential fix for #2192

test/functional/forum_topics_controller_test.rb

@@ -16,6 +16,25 @@ class ForumTopicsControllerTest < ActionController::TestCase
       CurrentUser.ip_addr = nil
     end
 
+    context "show action" do
+      should "render" do
+        get :show, {:id => @forum_topic.id}
+        assert_response :success
+      end
+
+      context "when the read_forum_topics session exceeds the maximum cookie size" do
+        setup do
+          @cookie_data = 1.upto(10_000).to_a.join(" ")
+        end
+
+        should "truncate" do
+          get :show, {:id => @forum_topic.id}, {:user_id => @user.id, :read_forum_topics => @cookie_data}
+          assert_response :success
+          assert_equal(1570, session[:read_forum_topics].size)
+        end
+      end
+    end
+
     context "index action" do
       should "list all forum topics" do
         get :index