Try to create a version record when associated object is touched

Before #1285, a version record was created when associated object is touched.
But because of Rails don't track implicit touch mutation[1], now PaperTail
don't create a version record was created when associated object is touched.

This patch try to keep creating a version record in that case by doing checking an
event and changed value.

Fixes #1339.

[1]: rails/rails@dcb8259

CHANGELOG.md

@@ -15,7 +15,9 @@ recommendations of [keepachangelog.com](http://keepachangelog.com/).
 
 ### Fixed
 
-- None
+- [#1376](https://github.com/paper-trail-gem/paper_trail/pull/1376) -
+  Create a version record when associated object was changed the same as
+  PaperTrail < v12.1.0.
 
 ## 12.2.0 (2022-01-21)
 

lib/paper_trail/events/update.rb

@@ -40,6 +40,20 @@ def data
         merge_metadata_into(data)
       end
 
+      # If it is a touch event, and changed are empty, it is assumed to be
+      # implicit `touch` mutation, and will a version is created.
+      #
+      # See https://github.com/rails/rails/commit/dcb825902d79d0f6baba956f7c6ec5767611353e
+      #
+      # @api private
+      def changed_notably?
+        if @is_touch && changes_in_latest_version.empty?
+          true
+        else
+          super
+        end
+      end
+
       private
 
       # @api private

spec/dummy_app/app/models/order.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class Order < ActiveRecord::Base
-  belongs_to :customer
+  belongs_to :customer, touch: :touched_at
   has_many :line_items
   has_paper_trail
 end

spec/dummy_app/db/migrate/20110208155312_set_up_test_tables.rb

@@ -267,6 +267,7 @@ def up
 
     create_table :customers, force: true do |t|
       t.string :name
+      t.datetime :touched_at, limit: 6
     end
 
     create_table :orders, force: true do |t|

spec/models/order_spec.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe Order, type: :model, versioning: true do
+  context "when the record destroyed" do
+    it "creates a version record for association" do
+      customer = Customer.create!
+      described_class.create!(customer: customer)
+      described_class.destroy_all
+
+      expect(customer.versions.count).to(eq(3))
+    end
+  end
+end