Delete attachments that have been unused for 24 hours

app/models/clean_up_unused_attachments.rb

@@ -0,0 +1,13 @@
+module CleanUpUnusedAttachments
+  def self.perform
+    S3File
+      .attachments
+      .where('became_unused_at < ?', 24.hours.ago)
+      .where(do_not_delete_unused: false)
+      .find_each do |s3_file|
+        # Double check became_unused_at
+        s3_file.update_unused
+        s3_file.destroy! if s3_file.unused?
+      end
+  end
+end

config/clockwork.rb

@@ -9,6 +9,7 @@ module Clockwork
         isolate_errors { CleanUpUnuploadedS3Files.perform }
         isolate_errors { CleanUpUntrackedS3Objects.perform }
         isolate_errors { CleanUpBlankDocuments.perform }
+        isolate_errors { CleanUpUnusedAttachments.perform }
       end
     end
   end

test/factories.rb

@@ -29,6 +29,11 @@
     content_type { 'image/png' }
   end
 
+  factory :documents_s3_file do
+    document
+    s3_file
+  end
+
   factory :settings do
     user
     data { { hello: 'world' }.to_json }

test/models/clean_up_unused_attachments_test.rb

@@ -0,0 +1,50 @@
+require 'test_helper'
+
+class CleanUpUnusedAttachmentsTest < ActiveSupport::TestCase
+  setup do
+    @user = create(:user)
+    @project = create(:project, owner: @user)
+    @document = create(:document, project: @project)
+    @s3_file = create(:s3_file, role: 'attachment', became_unused_at: 25.hours.ago, owner: @user)
+  end
+
+  test 'should delete unused attachments' do
+    perform
+    assert destroyed?, 'unused attachment should be deleted'
+  end
+
+  test 'should not delete used attachments, even if became_unused_at is wrong' do
+    create(:documents_s3_file, document: @document, s3_file: @s3_file)
+    @s3_file.update!(became_unused_at: 25.hours.ago)
+    perform
+    assert_not destroyed?, 'used attachment should not be deleted'
+  end
+
+  test 'should not delete recently used attachments' do
+    @s3_file.update!(became_unused_at: 23.hours.ago)
+    perform
+    assert_not destroyed?, 'recently used attachment should not be deleted'
+  end
+
+  test 'should not delete non-attachment s3 files' do
+    @s3_file.update!(role: 'project-image')
+    perform
+    assert_not destroyed?, 'non-attachment s3 file should not be deleted'
+  end
+
+  test 'should not delete attachments marked as do_not_delete_unused' do
+    @s3_file.update!(do_not_delete_unused: true)
+    perform
+    assert_not destroyed?, 'attachment marked as do_not_delete_unused should not be deleted'
+  end
+
+  private
+
+  def perform
+    ignore_s3 { CleanUpUnusedAttachments.perform }
+  end
+
+  def destroyed?
+    !S3File.find_by(id: @s3_file.id)
+  end
+end