UX: Don't change topic notification level when unassigning (#513)

* UX: Don't change topic notification level when unassigning

* Update test

lib/assigner.rb

@@ -372,22 +372,6 @@ class ::Assigner
         assigned_to_type: assignment.assigned_to_type,
       )
 
-      if assignment.assigned_to_user?
-        if TopicUser.exists?(
-             user_id: assignment.assigned_to_id,
-             topic: topic,
-             notification_level: TopicUser.notification_levels[:watching],
-             notifications_reason_id: TopicUser.notification_reasons[:plugin_changed],
-           )
-          TopicUser.change(
-            assignment.assigned_to_id,
-            topic.id,
-            notification_level: TopicUser.notification_levels[:tracking],
-            notifications_reason_id: TopicUser.notification_reasons[:plugin_changed],
-          )
-        end
-      end
-
       assigned_to = assignment.assigned_to
 
       if SiteSetting.unassign_creates_tracking_post && !silent

spec/lib/assigner_spec.rb

@@ -39,7 +39,7 @@ RSpec.describe Assigner do
       expect(TopicQuery.new(moderator, assigned: moderator.username).list_latest.topics).to eq([])
 
       expect(TopicUser.find_by(user: moderator).notification_level).to eq(
-        TopicUser.notification_levels[:tracking],
+        TopicUser.notification_levels[:watching],
       )
     end
 
@@ -122,23 +122,17 @@ RSpec.describe Assigner do
       }
     end
 
-    it "does not update notification level if it is not set by the plugin" do
+    it "does not update notification level when unassigned" 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],
+        TopicUser.notification_levels[:watching],
       )
     end