Use _ instead of .

app/controllers/registrations_controller.rb

@@ -7,7 +7,7 @@ class RegistrationsController < ApplicationController
     self.resource = resource_class.new(params[resource_name])
 
     if resource.save
-      flash[:"#{resource_name}.signed_up"] = true
+      flash[:"#{resource_name}_signed_up"] = true
       set_flash_message :notice, :signed_up
       sign_in_and_redirect(resource_name, resource)
     else

app/controllers/sessions_controller.rb

@@ -8,7 +8,7 @@ class SessionsController < ApplicationController
   def new
     Devise::FLASH_MESSAGES.each do |message|
       set_now_flash_message :alert, message if params.try(:[], message) == "true"
-    end unless flash[:"#{resource_name}.signed_up"]
+    end unless resource_just_signed_up?
     super
   end
 
@@ -30,4 +30,9 @@ class SessionsController < ApplicationController
     sign_out_and_redirect(resource_name)
   end
 
+  protected
+
+  def resource_just_signed_up?
+    flash[:"#{resource_name}_signed_up"]
+  end
 end

test/integration/registerable_test.rb

@@ -31,15 +31,15 @@ class RegistrationTest < ActionController::IntegrationTest
     fill_in 'password confirmation', :with => 'new_user123'
     click_button 'Sign up'
 
-    assert_equal true, @controller.send(:flash)[:"user.signed_up"]
+    assert_equal true, @controller.send(:flash)[:"user_signed_up"]
     assert_equal "You have signed up successfully.", @controller.send(:flash)[:notice]
 
     # For some reason flash is not being set correctly, so instead of getting the
     # "signed_up" message we get the unconfirmed one. Seems to be an issue with
     # the internal redirect by the hook and the tests.
-#    follow_redirect!
-#    assert_contain 'You have signed up successfully.'
-#    assert_not_contain 'confirm your account'
+    # follow_redirect!
+    # assert_contain 'You have signed up successfully.'
+    # assert_not_contain 'confirm your account'
 
     assert_not warden.authenticated?(:user)