FEATURE: Add option to immediately delete stub topics upon merge (#28228)

Currently to handle stub topics after merging, there are only options to (1) never delete a stub topic and (2) delete a stub topic after X amount of days. This adds the option to immediately delete a stub topic upon merge.

---------

Co-authored-by: Mark VanLandingham <markvanlan@gmail.com>
Co-authored-by: Renato Atilio <renato@discourse.org>

app/models/post_mover.rb

@@ -701,7 +701,19 @@ class PostMover
     @original_topic.update_status("closed", true, @user)
 
     days_to_deleting = SiteSetting.delete_merged_stub_topics_after_days
-    if days_to_deleting > 0
+    if days_to_deleting == 0
+      if Guardian.new(@user).can_delete?(@original_topic)
+        first_post = @original_topic.ordered_posts.first
+
+        PostDestroyer.new(
+          @user,
+          first_post,
+          context: I18n.t("topic_statuses.auto_deleted_by_merge"),
+        ).destroy
+
+        @original_topic.trash!(Discourse.system_user)
+      end
+    elsif days_to_deleting > 0
       @original_topic.set_or_create_timer(
         TopicTimer.types[:delete],
         days_to_deleting * 24,

config/locales/server.en.yml

@@ -2486,7 +2486,7 @@ en:
     notify_about_reviewable_item_after: "If there are reviewable items that haven’t been handled after this many hours, send a personal message to moderators. Set to 0 to disable."
 
     delete_drafts_older_than_n_days: "Delete drafts that have not been changed in more than (n) days."
-    delete_merged_stub_topics_after_days: "Number of days to wait before automatically deleting fully merged stub topics. Set to 0 to never delete stub topics."
+    delete_merged_stub_topics_after_days: "Number of days to wait before automatically deleting fully merged stub topics. Set to -1 to never delete. Set to 0 to immediately delete."
 
     bootstrap_mode_min_users: "Minimum number of users required to disable bootstrap mode and remove Getting Started button (set to 0 to disable, can take up to 24 hours)"
 
@@ -2910,6 +2910,7 @@ en:
     autoclosed_disabled: "This topic is now opened. New replies are allowed."
     autoclosed_disabled_lastpost: "This topic is now opened. New replies are allowed."
     auto_deleted_by_timer: "Automatically deleted by timer."
+    auto_deleted_by_merge: "Automatically deleted by merge."
 
   login:
     invalid_second_factor_method: "The selected two-factor method is invalid."

config/site_settings.yml

@@ -2828,7 +2828,7 @@ uncategorized:
 
   delete_merged_stub_topics_after_days:
     default: 7
-    min: 0
+    min: -1
 
   backup_drafts_to_pm_length:
     default: 0

db/migrate/20240807024301_update_delete_merged_stub_topics_after_days_setting.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+class UpdateDeleteMergedStubTopicsAfterDaysSetting < ActiveRecord::Migration[7.1]
+  def up
+    execute "UPDATE site_settings SET value = '-1' WHERE name = 'delete_merged_stub_topics_after_days' AND value = '0'"
+  end
+
+  def down
+    execute "UPDATE site_settings SET value = '0' WHERE name = 'delete_merged_stub_topics_after_days' AND value = '-1'"
+  end
+end

spec/models/post_mover_spec.rb

@@ -733,8 +733,8 @@ RSpec.describe PostMover do
             expect(timer).to be_nil
           end
 
-          it "doesn't schedule topic deleting when all posts were moved if it's disabled in settings" do
-            SiteSetting.delete_merged_stub_topics_after_days = 0
+          it "doesn't schedule topic deleting when all posts were moved if it's disabled (-1)" do
+            SiteSetting.delete_merged_stub_topics_after_days = -1
 
             topic.expects(:add_moderator_post).twice
             posts_to_move = [p1.id, p2.id, p3.id, p4.id]
@@ -742,10 +742,25 @@ RSpec.describe PostMover do
               topic.move_posts(user, posts_to_move, destination_topic_id: destination_topic.id)
             expect(moved_to).to be_present
 
+            expect(Topic.with_deleted.find(topic.id).deleted_at).to be_nil
+
             timer = topic.topic_timers.find_by(status_type: TopicTimer.types[:delete])
             expect(timer).to be_nil
           end
 
+          it "immediately deletes topic when delete_merged_stub_topics_after_days is 0" do
+            SiteSetting.delete_merged_stub_topics_after_days = 0
+            freeze_time
+
+            topic.expects(:add_moderator_post).twice
+            posts_to_move = [p1.id, p2.id, p3.id, p4.id]
+            moved_to =
+              topic.move_posts(user, posts_to_move, destination_topic_id: destination_topic.id)
+            expect(moved_to).to be_present
+
+            expect(Topic.with_deleted.find(topic.id).deleted_at).to be_present
+          end
+
           it "ignores moderator posts and closes the topic if all regular posts were moved" do
             add_moderator_post_to topic, Post.types[:moderator_action]
             add_moderator_post_to topic, Post.types[:small_action]