Ability to skip email validation via a plugin

app/models/user.rb

@@ -73,7 +73,7 @@ class User < ActiveRecord::Base
   validates_presence_of :username
   validate :username_validator, if: :username_changed?
   validates :email, presence: true, uniqueness: true
-  validates :email, email: true, if: Proc.new { |u| !u.staged && u.email_changed? }
+  validates :email, email: true, if: :should_validate_email?
   validate :password_validator
   validates :name, user_full_name: true, if: :name_changed?
   validates :ip_address, allowed_ip_address: {on: :create, message: :signup_not_allowed}
@@ -102,6 +102,9 @@ class User < ActiveRecord::Base
     TopicViewItem.delete_all(user_id: self.id)
   end
 
+  # Skip validating email, for example from a particular auth provider plugin
+  attr_accessor :skip_email_validation
+
   # Whether we need to be sending a system message after creation
   attr_accessor :send_welcome_message
 
@@ -247,6 +250,10 @@ class User < ActiveRecord::Base
     used_invite.try(:invited_by)
   end
 
+  def should_validate_email?
+    return !skip_email_validation && !staged? && email_changed?
+  end
+
   # Approve this user
   def approve(approved_by, send_mail=true)
     self.approved = true

app/services/user_authenticator.rb

@@ -12,6 +12,8 @@ class UserAuthenticator
     else
       @user.password_required!
     end
+
+    @user.skip_email_validation = true if @session && @session[:skip_email_validation].present?
   end
 
   def has_authenticator?

lib/auth/result.rb

@@ -3,7 +3,8 @@ class Auth::Result
                 :email_valid, :extra_data, :awaiting_activation,
                 :awaiting_approval, :authenticated, :authenticator_name,
                 :requires_invite, :not_allowed_from_ip_address,
-                :admin_not_allowed_from_ip_address, :omit_username
+                :admin_not_allowed_from_ip_address, :omit_username,
+                :skip_email_validation
 
   attr_accessor :failed,
                 :failed_reason
@@ -23,7 +24,8 @@ class Auth::Result
       omit_username: omit_username,
       name: name,
       authenticator_name: authenticator_name,
-      extra_data: extra_data }
+      extra_data: extra_data,
+      skip_email_validation: !!skip_email_validation }
   end
 
   def to_client_hash

spec/models/user_spec.rb

@@ -477,6 +477,13 @@ describe User do
       expect(Fabricate.build(:user, email: 'notgood@sub.domain.com')).not_to be_valid
     end
 
+    it 'skips the blacklist if skip_email_validation is set' do
+      SiteSetting.email_domains_blacklist = 'domain.com'
+      user = Fabricate.build(:user, email: 'notgood@sub.domain.com')
+      user.skip_email_validation = true
+      expect(user).to be_valid
+    end
+
     it 'blacklist should not reject developer emails' do
       Rails.configuration.stubs(:developer_emails).returns('developer@discourse.org')
       SiteSetting.email_domains_blacklist = 'discourse.org'