only remove accounts containing underscores

app/workers/scheduler/old_account_cleanup_scheduler.rb

@@ -28,17 +28,13 @@ class Scheduler::OldAccountCleanupScheduler
       .where("domain IS NULL")
       # id -99 is the instance actor
       .where("id <> -99")
-      # don't delete admin
-      .where("username <> 'admin'")
-      # don't delete crepels
-      .where("username <> 'crepels'")
-      # don't delete alice
-      .where("username <> 'alice'")
+      # only delete accounts whose username contains underscores (those are auto-generated)
+      .where("username LIKE '%\\_%'")
       .where("created_at < ?", 1.day.ago)
       .order(created_at: :asc)
       .limit(MAX_DELETIONS_PER_JOB)
       .each do |account|
-        AccountDeletionWorker.perform_async(account.id, { :reserve_username => false })
+        AccountDeletionWorker.perform_async(account.id, { 'reserve_username' => false })
       end
   end
 end

spec/workers/scheduler/old_account_cleanup_scheduler_spec.rb

@@ -0,0 +1,33 @@
+require 'json'
+require 'rails_helper'
+
+RSpec.describe Scheduler::OldAccountCleanupScheduler do
+  subject { described_class.new }
+  let!(:generated_user) { Fabricate(:account, username: 'containing_underscore', created_at: 25.hours.ago) }
+  let!(:alice) { Fabricate(:account, username: 'alice', created_at: 25.hours.ago) }
+  let!(:generated_user_other_instance) { Fabricate(:account, username: 'containing_underscore', domain: 'example.com', created_at: 25.hours.ago) }
+  let!(:instance_actor) { Fabricate(:account, id: 99, created_at: 25.hours.ago) }
+
+  describe '#perform' do
+    it 'removes auto-generated user-accounts that are older than one day' do
+      expect { subject.perform }.to change { Account.exists?(generated_user.id) }.from(true).to(false)
+    end
+
+    it 'does not remove auto-generated user-accounts that are younger than one day' do
+      generated_user.update!(created_at: 23.hours.ago)
+      expect { subject.perform }.not_to change { Account.exists?(generated_user.id) }.from(true)
+    end
+
+    it 'does not remove accounts with underscores from other instances' do
+      expect { subject.perform }.not_to change { Account.exists?(generated_user_other_instance.id) }.from(true)
+    end
+
+    it 'does not remove accounts without underscores' do
+      expect { subject.perform }.not_to change { Account.exists?(alice.id) }.from(true)
+    end
+
+    it 'does not remove instance actor' do
+      expect { subject.perform }.not_to change { Account.exists?(instance_actor.id) }.from(true)
+    end
+  end
+end