FIX: Set first visit PM notification level to group default notification level.

https://meta.discourse.org/t/notifications-not-received-for-private-messages-im-invited-to/71577/21?u=tgxworld

app/models/topic_user.rb

@@ -194,7 +194,18 @@ SQL
              notification_type: Notification.types[:invited_to_private_message]
            ).exists?
 
-          attrs[:notification_level] = notification_levels[:watching]
+          group_notification_level = Group
+            .joins("LEFT OUTER JOIN group_users gu ON gu.group_id = groups.id AND gu.user_id = #{user_id}")
+            .joins("LEFT OUTER JOIN topic_allowed_groups tag ON tag.topic_id = #{topic_id}")
+            .where("gu.id IS NOT NULL AND tag.id IS NOT NULL")
+            .pluck(:default_notification_level)
+            .first
+
+          if group_notification_level.present?
+            attrs[:notification_level] = group_notification_level
+          else
+            attrs[:notification_level] = notification_levels[:watching]
+          end
         else
           auto_track_after = UserOption.where(user_id: user_id).pluck(:auto_track_topics_after_msecs).first
           auto_track_after ||= SiteSetting.default_other_auto_track_topics_after_msecs

spec/models/topic_user_spec.rb

@@ -267,6 +267,31 @@ describe TopicUser do
         expect(TopicUser.get(topic, another_user).notification_level)
           .to eq(TopicUser.notification_levels[:regular])
       end
+
+      describe 'inviting a group' do
+        let(:group) do
+          Fabricate(:group,
+            default_notification_level: NotificationLevels.topic_levels[:tracking]
+          )
+        end
+
+        it "should use group's default notification level" do
+          another_user = Fabricate(:user)
+          group.add(another_user)
+          topic.invite_group(target_user, group)
+          TopicUser.track_visit!(topic.id, another_user.id)
+
+          expect(TopicUser.get(topic, another_user).notification_level)
+            .to eq(TopicUser.notification_levels[:tracking])
+
+          another_user = Fabricate(:user)
+          topic.invite(target_user, another_user.username)
+          TopicUser.track_visit!(topic.id, another_user.id)
+
+          expect(TopicUser.get(topic, another_user).notification_level)
+            .to eq(TopicUser.notification_levels[:watching])
+        end
+      end
     end
 
     context 'auto tracking' do