username now can only contain letters numbers, periods, and underscores

app/models/user.rb

@@ -43,8 +43,7 @@ class User
   before_validation :strip_username, :on => :create
   validates_presence_of :username
   validates_uniqueness_of :username, :case_sensitive => false
-  validates_format_of :username, :without => /\s/
-
+  validates_format_of :username, :with => /\A[A-Za-z0-9_.]+\z/ 
   validates_with InvitedUserValidator
 
   one :person, :class_name => 'Person', :foreign_key => :owner_id

spec/models/user_spec.rb

@@ -73,6 +73,11 @@ describe User do
         user = Factory.build(:user, :username => "bobby tables")
         user.should_not be_valid
       end
+
+      it 'can not contain non url safe characters' do
+        user = Factory.build(:user, :username => "kittens;")
+        user.should_not be_valid
+      end
     end
 
     describe "of email" do