a membership with no user is always notifiable

app/models/member.rb

@@ -276,6 +276,14 @@ class Member < ActiveRecord::Base
     @notification_setting ||= user.notification_settings_for(source)
   end
 
+  def notifiable?(type, opts={})
+    # always notify when there isn't a user yet
+    return true if user.blank?
+
+    NotificationRecipientService.notifiable?(user, type, notifiable_options.merge(opts))
+  end
+
+
   private
 
   def send_invite
@@ -333,7 +341,7 @@ class Member < ActiveRecord::Base
     NotificationService.new
   end
 
-  def notifiable?(type, opts={})
-    raise 'abstract'
+  def notifiable_options
+    {}
   end
 end

app/models/members/group_member.rb

@@ -30,8 +30,8 @@ class GroupMember < Member
     'Group'
   end
 
-  def notifiable?(type, opts={})
-    NotificationRecipientService.notifiable?(user, type, { group: group }.merge(opts))
+  def notifiable_options
+    { group: group }
   end
 
   private

app/models/members/project_member.rb

@@ -87,8 +87,8 @@ class ProjectMember < Member
     project.owner == user
   end
 
-  def notifiable?(type, opts={})
-    NotificationRecipientService.notifiable?(user, type, { project: project }.merge(opts))
+  def notifiable_options
+    { project: project }
   end
 
   private