FIX: Change notification_level back to tracking only if set by plugin.

lib/topic_assigner.rb

@@ -232,12 +232,20 @@ SQL
 
       post.publish_change_to_clients!(:revised, reload_topic: true)
 
+      if TopicUser.exists?(
+        user_id: assigned_to_id,
+        topic: @topic,
+        notification_level: TopicUser.notification_levels[:watching],
+        notifications_reason_id: TopicUser.notification_reasons[:plugin_changed]
+      )
+
         TopicUser.change(
           assigned_to_id,
           @topic.id,
           notification_level: TopicUser.notification_levels[:tracking],
           notifications_reason_id: TopicUser.notification_reasons[:plugin_changed]
         )
+      end
 
       assigned_user = User.find_by(id: assigned_to_id)
       MessageBus.publish(

spec/lib/topic_assigner_spec.rb

@@ -49,6 +49,22 @@ RSpec.describe TopicAssigner do
         .to eq(TopicUser.notification_levels[:tracking])
     end
 
+    it 'does not update notification level if it is not set by the plugin' do
+      assigner.assign(moderator)
+
+      expect(TopicUser.find_by(user: moderator).notification_level)
+        .to eq(TopicUser.notification_levels[:watching])
+
+      TopicUser.change(moderator.id, topic.id,
+        notification_level: TopicUser.notification_levels[:muted]
+      )
+
+      assigner.unassign
+
+      expect(TopicUser.find_by(user: moderator, topic: topic).notification_level)
+        .to eq(TopicUser.notification_levels[:muted])
+    end
+
     it "can unassign all a user's topics at once" do
       assigner.assign(moderator)
       TopicAssigner.unassign_all(moderator, moderator)