FIX: don't send repeated notifications that there are pending users who need to be approved to moderators who haven't read the previous notification

app/jobs/scheduled/pending_users_reminder.rb

@@ -9,7 +9,24 @@ module Jobs
       if SiteSetting.must_approve_users
         count = AdminUserIndexQuery.new({query: 'pending'}).find_users_query.count
         if count > 0
-          GroupMessage.create(Group[:moderators].name, :pending_users_reminder, {limit_once_per: false, message_params: {count: count}})
+          target_usernames = Group[:moderators].users.map do |u|
+            u.id > 0 && u.notifications.joins(:topic)
+                                       .where("notifications.id > ?", u.seen_notification_id)
+                                       .where("notifications.read = false")
+                                       .where("topics.subtype = '#{TopicSubtype.pending_users_reminder}'")
+                                       .count == 0 ? u.username : nil
+          end.compact
+
+          unless target_usernames.empty?
+            PostCreator.create(
+              Discourse.system_user,
+              target_usernames: target_usernames,
+              archetype: Archetype.private_message,
+              subtype: TopicSubtype.pending_users_reminder,
+              title: I18n.t("system_messages.pending_users_reminder.subject_template", {count: count}),
+              raw: I18n.t("system_messages.pending_users_reminder.text_body_template", {count: count, base_url: Discourse.base_url})
+            )
+          end
         end
       end
     end

lib/topic_subtype.rb

@@ -37,6 +37,10 @@ class TopicSubtype
     'notify_user'
   end
 
+  def self.pending_users_reminder
+    'pending_users'
+  end
+
   def self.register(name, options={})
     @subtypes ||= {}
     @subtypes[name] = TopicSubtype.new(name, options)

spec/jobs/pending_users_reminder_spec.rb

@@ -9,13 +9,15 @@ describe Jobs::PendingUsersReminder do
 
     it "doesn't send a message to anyone when there are no pending users" do
       AdminUserIndexQuery.any_instance.stubs(:find_users_query).returns(stub_everything(count: 0))
-      GroupMessage.any_instance.expects(:create).never
+      PostCreator.expects(:create).never
       Jobs::PendingUsersReminder.new.execute({})
     end
 
-    it "sends a message to moderators when there are pending users" do
+    it "sends a message when there are pending users" do
+      Fabricate(:moderator)
+      Group.refresh_automatic_group!(:moderators)
       AdminUserIndexQuery.any_instance.stubs(:find_users_query).returns(stub_everything(count: 1))
-      GroupMessage.expects(:create).with(Group[:moderators].name, :pending_users_reminder, anything)
+      PostCreator.expects(:create).once
       Jobs::PendingUsersReminder.new.execute({})
     end
   end
@@ -27,7 +29,7 @@ describe Jobs::PendingUsersReminder do
 
     it "doesn't send a message to anyone when there are pending users" do
       AdminUserIndexQuery.any_instance.stubs(:find_users_query).returns(stub_everything(count: 1))
-      GroupMessage.any_instance.expects(:create).never
+      PostCreator.expects(:create).never
       Jobs::PendingUsersReminder.new.execute({})
     end
   end