add email_scope option for email uniqueness validator

lib/devise.rb

@@ -115,6 +115,10 @@ module Test
   mattr_accessor :email_regexp
   @@email_regexp = /\A[^@\s]+@[^@\s]+\z/
 
+   # Option to scope the email uniqueness validator
+   mattr_accessor :email_scope
+   @@email_scope = nil
+
   # Range validation for password length
   mattr_accessor :password_length
   @@password_length = 6..128

lib/devise/models/validatable.rb

@@ -12,6 +12,7 @@ module Models
     # Validatable adds the following options to devise_for:
     #
     #   * +email_regexp+: the regular expression used to validate e-mails;
+    #   * +email_scope+: option to scope the email uniqueness validator;
     #   * +password_length+: a range expressing password length. Defaults to 6..128.
     #
     module Validatable
@@ -30,10 +31,10 @@ def self.included(base)
         base.class_eval do
           validates_presence_of   :email, if: :email_required?
           if Devise.activerecord51?
-            validates_uniqueness_of :email, allow_blank: true, case_sensitive: true, if: :will_save_change_to_email?
+            validates_uniqueness_of :email, allow_blank: true, case_sensitive: true, if: :will_save_change_to_email?, scope: email_scope
             validates_format_of     :email, with: email_regexp, allow_blank: true, if: :will_save_change_to_email?
           else
-            validates_uniqueness_of :email, allow_blank: true, if: :email_changed?
+            validates_uniqueness_of :email, allow_blank: true, if: :email_changed?, scope: email_scope
             validates_format_of     :email, with: email_regexp, allow_blank: true, if: :email_changed?
           end
 
@@ -66,7 +67,7 @@ def email_required?
       end
 
       module ClassMethods
-        Devise::Models.config(self, :email_regexp, :password_length)
+        Devise::Models.config(self, :email_regexp, :password_length, :email_scope)
       end
     end
   end

lib/generators/templates/devise.rb

@@ -185,6 +185,9 @@
   # to give user feedback and not to assert the e-mail validity.
   config.email_regexp = /\A[^@\s]+@[^@\s]+\z/
 
+  # Option to scope the email uniqueness validator. Default is nil;
+  # config.email_scope = [:username]
+
   # ==> Configuration for :timeoutable
   # The time you want to timeout the user session without activity. After this
   # time the user will be asked for credentials again. Default is 30 minutes.

test/models/validatable_test.rb

@@ -26,6 +26,12 @@ class ValidatableTest < ActiveSupport::TestCase
     assert user.valid?
   end
 
+  test 'should allow non-unique emails using email_scope attribute' do
+    existing_user = create_user_with_scope
+    user = new_user_with_scope(email: existing_user.email, username: "New username")
+    assert user.valid?
+  end
+
   test 'should require correct email format if email has changed, allowing blank' do
     user = new_user(email: '')
     assert user.invalid?

test/rails_app/app/active_record/user_with_scope.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+require 'shared_user_with_scope'
+
+class UserWithScope < ActiveRecord::Base
+  self.table_name = 'users'
+  include Shim
+  include SharedUserWithScope
+end
+

test/rails_app/app/mongoid/user_with_scope.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require "shared_user_with_scope"
+
+class UserWithScope
+  include Mongoid::Document
+  include Shim
+  include SharedUserWithScope
+
+  field :username, type: String
+
+  ## Database authenticatable
+  field :email, type: String, default: ""
+  field :encrypted_password, type: String, default: ""
+
+  ## Recoverable
+  field :reset_password_token, type: String
+  field :reset_password_sent_at, type: Time
+
+  ## Rememberable
+  field :remember_created_at, type: Time
+
+  ## Trackable
+  field :sign_in_count, type: Integer, default: 0
+  field :current_sign_in_at, type: Time
+  field :last_sign_in_at, type: Time
+  field :current_sign_in_ip, type: String
+  field :last_sign_in_ip, type: String
+
+  validates :email, presence: true
+end

test/rails_app/config/initializers/devise.rb

@@ -101,6 +101,9 @@
   # Regex to use to validate the email address
   # config.email_regexp = /^([\w\.%\+\-]+)@([\w\-]+\.)+([\w]{2,})$/i
 
+  # Option to scope the email uniqueness validator. Default is nil;
+  # config.email_scope = [:subdomain]
+
   # ==> Configuration for :timeoutable
   # The time you want to timeout the user session without activity. After this
   # time the user will be asked for credentials again. Default is 30 minutes.

test/rails_app/lib/shared_user_with_scope.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+module SharedUserWithScope
+  extend ActiveSupport::Concern
+
+  included do
+    devise :database_authenticatable, :lockable, :recoverable,
+           :registerable, :rememberable, :timeoutable,
+           :trackable, :validatable, email_scope: [:username]
+  end
+end

test/support/helpers.rb

@@ -38,6 +38,10 @@ def new_user(attributes = {})
     User.new(valid_attributes(attributes))
   end
 
+  def new_user_with_scope(attributes = {})
+    UserWithScope.new(valid_attributes(attributes))
+  end
+
   def create_user(attributes = {})
     User.create!(valid_attributes(attributes))
   end
@@ -56,6 +60,10 @@ def create_user_with_validations(attributes = {})
     UserWithValidations.create!(valid_attributes(attributes))
   end
 
+  def create_user_with_scope(attributes={})
+    UserWithScope.create!(valid_attributes(attributes))
+  end
+
   # Execute the block setting the given values and restoring old values after
   # the block is executed.
   def swap(object, new_values)