This bug report script demonstrates a bug with PaperTrail when the ActiveRecord model has both database and model defaults for a serialized field

paper_trail_serialization_bug_report.rb

# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }
  
  gem "activerecord", "~> 7.0.0"
  gem "sqlite3"

  # Activate the gem you are reporting the issue against.
  gem "paper_trail", "~> 14.0.0"
end

require "active_record"
require "paper_trail"
require "minitest/autorun"
require "logger"

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :paper_trailed_record_ones, force: true do |t|
    t.text :serialized_array_with_db_and_model_defaults_for_empty_array, default: [].to_yaml
  end
  
  create_table :paper_trailed_record_twos, force: true do |t|
    t.text :serialized_array_with_db_default_for_empty_array, default: [].to_yaml
  end
  
  create_table :paper_trailed_record_threes, force: true do |t|
    t.text :serialized_array_with_model_default_for_empty_array
  end
  
  create_table :paper_trailed_record_fours, force: true do |t|
    t.text :serialized_array_with_db_and_model_defaults_for_filled_array, default: [1].to_yaml
  end
  
  create_table :paper_trailed_record_fives, force: true do |t|
    t.text :serialized_array_with_db_default_for_filled_array, default: [1].to_yaml
  end
  
  create_table :paper_trailed_record_sixes, force: true do |t|
    t.text :serialized_array_with_model_default_for_filled_array
  end
  
  create_table :paper_trailed_record_sevens, force: true do |t|
    t.text :serialized_array_with_no_defaults
  end
  
  create_table :non_paper_trailed_records, force: true do |t|
    t.text :serialized_array_with_db_and_model_defaults_for_empty_array, default: [].to_yaml
    t.text :serialized_array_with_db_default_for_empty_array, default: [].to_yaml
    t.text :serialized_array_with_model_default_for_empty_array
    
    t.text :serialized_array_with_db_and_model_defaults_for_filled_array, default: [1].to_yaml
    t.text :serialized_array_with_db_default_for_filled_array, default: [1].to_yaml
    t.text :serialized_array_with_model_default_for_filled_array
    
    t.text :serialized_array_with_no_defaults
  end
  
  create_table "versions", force: true do |t|
    t.string "item_type", null: false
    t.bigint "item_id", null: false
    t.string "event", null: false
    t.string "whodunnit"
    t.text "object", limit: 1073741823
    t.datetime "created_at"
    t.text "object_changes", limit: 1073741823
    t.index ["item_type", "item_id"], name: "index_versions_on_item_type_and_item_id"
  end
end

class PaperTrailedRecordOne < ActiveRecord::Base
  has_paper_trail
  
  serialize :serialized_array_with_db_and_model_defaults_for_empty_array, Array
  attribute :serialized_array_with_db_and_model_defaults_for_empty_array, default: []
end

class PaperTrailedRecordTwo < ActiveRecord::Base
  has_paper_trail
  
  serialize :serialized_array_with_db_default_for_empty_array, Array
end

class PaperTrailedRecordThree < ActiveRecord::Base
  has_paper_trail
  
  serialize :serialized_array_with_model_default_for_empty_array, Array
  attribute :serialized_array_with_model_default_for_empty_array, default: []
end

class PaperTrailedRecordFour < ActiveRecord::Base
  has_paper_trail
  
  serialize :serialized_array_with_db_and_model_defaults_for_filled_array, Array
  attribute :serialized_array_with_db_and_model_defaults_for_filled_array, default: [1]
end

class PaperTrailedRecordFive < ActiveRecord::Base
  has_paper_trail
  
  serialize :serialized_array_with_db_default_for_filled_array, Array
end

class PaperTrailedRecordSix < ActiveRecord::Base
  has_paper_trail
  
  serialize :serialized_array_with_model_default_for_filled_array, Array
  attribute :serialized_array_with_model_default_for_filled_array, default: [1]
end

class PaperTrailedRecordSeven < ActiveRecord::Base
  has_paper_trail
  
  serialize :serialized_array_with_no_defaults, Array
end

class NonPaperTrailedRecord < ActiveRecord::Base
  serialize :serialized_array_with_db_and_model_defaults_for_empty_array, Array
  attribute :serialized_array_with_db_and_model_defaults_for_empty_array, default: []
  
  serialize :serialized_array_with_db_default_for_empty_array, Array
  
  serialize :serialized_array_with_model_default_for_empty_array, Array
  attribute :serialized_array_with_model_default_for_empty_array, default: []
  
  serialize :serialized_array_with_db_and_model_defaults_for_filled_array, Array
  attribute :serialized_array_with_db_and_model_defaults_for_filled_array, default: [1]
  
  serialize :serialized_array_with_db_default_for_filled_array, Array
  
  serialize :serialized_array_with_model_default_for_filled_array, Array
  attribute :serialized_array_with_model_default_for_filled_array, default: [1]
  
  serialize :serialized_array_with_no_defaults, Array
end

# ---

class BugTest < Minitest::Test
  def test_the_version
    assert PaperTrail.gem_version.is_a?(::Gem::Version)
    assert_equal ::PaperTrail::VERSION::STRING, PaperTrail.gem_version.to_s
  end
  
  def test_non_paper_trailed_record_can_be_created_with_no_attributes
    record = NonPaperTrailedRecord.create!
    assert record
  end
  
  # ---
  
  def test_paper_trailed_record_with_serialized_array_with_db_and_model_defaults_for_empty_array_can_be_created_with_no_attributes
    record = PaperTrailedRecordOne.create!
    assert record
    
    # will raise ActiveRecord::SerializationTypeMismatch
  end
  
  def test_paper_trailed_record_with_serialized_array_with_db_default_for_empty_array_can_be_created_with_no_attributes
    record = PaperTrailedRecordTwo.create!
    assert record
  end
  
  def test_paper_trailed_record_with_serialized_array_with_model_default_for_empty_array_can_be_created_with_no_attributes
    record = PaperTrailedRecordThree.create!
    assert record
  end
  
  def test_paper_trailed_record_with_serialized_array_with_db_and_model_defaults_for_filled_array_can_be_created_with_no_attributes
    record = PaperTrailedRecordFour.create!
    assert record
    
    # will raise ActiveRecord::SerializationTypeMismatch
  end
  
  def test_paper_trailed_record_with_serialized_array_with_db_default_for_filled_array_can_be_created_with_no_attributes
    record = PaperTrailedRecordFive.create!
    assert record
  end
  
  def test_paper_trailed_record_with_serialized_array_with_model_default_for_filled_array_can_be_created_with_no_attributes
    record = PaperTrailedRecordSix.create!
    assert record
  end
  
  def test_paper_trailed_record_with_serialized_array_with_no_defaults_can_be_created_with_no_attributes
    record = PaperTrailedRecordSeven.create!
    assert record
  end
end