we need to eval what were sent

lib/shoulda/controller/macros.rb

@@ -144,14 +144,19 @@ def should_respond_with_content_type(content_type)
           end
         end
 
-        # Macro that creates a test asserting that the value returned from the session when accessed
-        # with the argument 'key' is equal to the value sent as the argument 'expected'
+        # Macro that creates a test asserting that a value returned from the session is correct.
+        # The given string is evaled to produce the resulting redirect path.  All of the instance variables
+        # set by the controller are available to the evaled string.
+        # Example:
         #
-        #   should_return_from_session :user_id, @user.id
-        #   should_return_from_session :user_id, nil
+        #   should_return_from_session :user_id, '@user.id'
+        #   should_return_from_session :message, '"Free stuff"'
         def should_return_from_session(key, expected)
           should "return the correct value from the session for key #{key}" do
-            assert_equal expected, session[key], "Expected #{expected.inspect} but was #{session[key]}"
+            instantiate_variables_from_assigns do
+              expected_value = eval(expected, self.send(:binding), __FILE__, __LINE__)
+              assert_equal expected_value, session[key], "Expected #{expected_value.inspect} but was #{session[key]}"
+            end
           end
         end
 

test/functional/posts_controller_test.rb

@@ -52,10 +52,12 @@ def setup
     context "viewing posts for a user with rss format" do
       setup do
         get :index, :user_id => users(:first), :format => 'rss'
+        @user = users(:first)
       end
       should_respond_with :success
       should_respond_with_content_type 'application/rss+xml'
-      should_return_from_session :special, '$2 off your next purchase'
+      should_return_from_session :special, "'$2 off your next purchase'"
+      should_return_from_session :special_user_id, '@user.id'
       should_assign_to :user, :posts
       should_not_assign_to :foo, :bar
     end

test/rails_root/app/controllers/posts_controller.rb

@@ -11,6 +11,7 @@ def index
       format.rss do
         headers['Content-Type'] = 'application/rss+xml'
         session[:special] = '$2 off your next purchase'
+        session[:special_user_id] = @user.id
         head :ok
       end
     end