Added a more thorough email format validation regex for User

lib/clearance/user.rb

@@ -50,7 +50,7 @@ def self.included(model)
         model.class_eval do
           validates_presence_of     :email, :unless => :email_optional?
           validates_uniqueness_of   :email, :case_sensitive => false, :allow_blank => true
-          validates_format_of       :email, :with => %r{.+@.+\..+}, :allow_blank => true
+          validates_format_of       :email, :with => %r{^[a-z0-9!#\$%&'*+\/=?^_`{|}~-]+(?:\.[a-z0-9!#\$%&'*+\/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?$}i, :allow_blank => true
 
           validates_presence_of     :password, :unless => :password_optional?
           validates_confirmation_of :password

test/models/user_test.rb

@@ -12,7 +12,11 @@ class UserTest < ActiveSupport::TestCase
   context "When signing up" do
     should validate_presence_of(:email)
     should validate_presence_of(:password)
+    should allow_value("foo@example.co.uk").for(:email)
     should allow_value("foo@example.com").for(:email)
+    should_not allow_value("foo@").for(:email)
+    should_not allow_value("foo@example..com").for(:email)
+    should_not allow_value("foo@.example.com").for(:email)
     should_not allow_value("foo").for(:email)
     should_not allow_value("example.com").for(:email)