added job for cleaning up duplicate thread followers

Author: Oaphi

app/jobs/clean_up_thread_followers_job.rb

@@ -0,0 +1,24 @@
+class CleanUpThreadFollowersJob < ApplicationJob
+  queue_as :default
+
+  def perform
+    sql = File.read(Rails.root.join('db/scripts/threads_with_duplicate_followers.sql'))
+    threads = ActiveRecord::Base.connection.execute(sql).to_a
+
+    threads.each do |thread|
+      user_id, thread_id = thread
+
+      followers = ThreadFollower.where(comment_thread_id: thread_id, user_id: user_id)
+
+      next unless followers.many?
+
+      duplicate = followers.first
+      result = duplicate.destroy
+
+      unless result
+        puts "failed to destroy thread follower duplicate \"#{duplicate.id}\""
+        duplicate.errors.each { |e| puts e.full_message }
+      end
+    end
+  end
+end

config/schedule.rb

@@ -26,6 +26,10 @@
   runner 'scripts/run_complaints_closure.rb'
 end
 
+every 7.days, at: '02:35' do
+  runner 'scripts/run_thread_followers_cleanup.rb'
+end
+
 every 6.hours do
   runner 'scripts/recalc_abilities.rb'
 end

db/scripts/threads_with_duplicate_followers.sql

@@ -0,0 +1,13 @@
+select
+  user_id,
+  comment_thread_id,
+  count(*) as count
+from
+  thread_followers
+where
+  post_id is null
+group by
+  user_id,
+  comment_thread_id
+having
+  count > 1;

scripts/run_thread_followers_cleanup.rb

@@ -0,0 +1 @@
+CleanUpThreadFollowersJob.perform_later

test/fixtures/comment_threads.yml

@@ -82,3 +82,10 @@ without_activity:
   community: sample
   created_at: 2020-01-01T00:00:00.000000Z
   updated_at: 2020-01-01T00:00:00.000000Z
+
+without_followers:
+  title: Comment thread without any followers
+  title: Comment thread without activity
+  reply_count: 0
+  post: question_one
+  community: sample

test/jobs/clean_up_thread_followers_job_test.rb

@@ -0,0 +1,19 @@
+require 'test_helper'
+
+class CleanUpThreadFollowersJobTest < ActiveJob::TestCase
+  test 'should correctly clean up thread followers' do
+    thread = comment_threads(:without_followers)
+    std_usr = users(:standard_user)
+
+    ThreadFollower.create(comment_thread: thread, user: std_usr)
+    ThreadFollower.create(comment_thread: thread, user: std_usr)
+    assert_equal 2, ThreadFollower.where(comment_thread: thread, user: std_usr).size
+
+    perform_enqueued_jobs do
+      CleanUpThreadFollowersJob.perform_later
+    end
+
+    assert_performed_jobs 1
+    assert_equal 1, ThreadFollower.where(comment_thread: thread, user: std_usr).size
+  end
+end