Trying to reproduce an issue with default scopes and paper_trail starting with Rails 5.1

paper_trail_bug_report_template.rb

# Use this template to report PaperTrail bugs.
# Please include only the minimum code necessary to reproduce your issue.
require "bundler/inline"

# STEP ONE: What versions are you using?
gemfile(true) do
  ruby "2.3.1"
  source "https://rubygems.org"
  gem "activerecord", "5.1.1"
  gem 'rspec', '3.6.0'
  gem "paper_trail", "7.0.3", require: false
  gem "sqlite3"
end

require "active_record"
require "logger"


# Please use sqlite for your bug reports, if possible.
ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
ActiveRecord::Base.logger = nil
ActiveRecord::Schema.define do
  # STEP TWO: Define your tables here.
  create_table :mailing_lists, force: true do |t|
    t.string :name
    t.boolean :active, default: true
    t.timestamps null: false
  end

  create_table :versions do |t|
    t.string :item_type, null: false
    t.integer :item_id, null: false
    t.string :event, null: false
    t.string :whodunnit
    t.text :object, limit: 1_073_741_823
    t.text :object_changes, limit: 1_073_741_823
    t.integer :transaction_id
    t.datetime :created_at
  end
  add_index :versions, %i[item_type item_id]
  add_index :versions, [:transaction_id]

end
ActiveRecord::Base.logger = Logger.new(STDOUT)
require "paper_trail/config"

# STEP THREE: Configure PaperTrail as you would in your initializer
PaperTrail::Config.instance.track_associations = false


require "paper_trail"


# STEP FOUR: Define your AR models here.
class MailingList < ActiveRecord::Base
  has_paper_trail ignore: :updated_at
  validates     :name, presence: true, uniqueness: true
  default_scope { where(active: true).order(:name) }
end


require 'rspec'
require 'rspec/autorun'


#PaperTrail::Rails::Engine.eager_load!             # https://github.com/airblade/paper_trail/issues/392

# STEP FIVE: Please write a test that demonstrates your issue.
RSpec.describe "with default_scope" do

  it "validations are working" do
    MailingList.create(name: "1")
    expect{MailingList.create!(name: "1")}.to raise_error(ActiveRecord::RecordInvalid).with_message(/Name has already been taken/)
  end

  it "default_scope is working" do
    expect(MailingList.all.to_sql).to eq "SELECT \"mailing_lists\".* FROM \"mailing_lists\" WHERE \"mailing_lists\".\"active\" = 't' ORDER BY \"mailing_lists\".\"name\" ASC"
  end

  it "paper_trail works on attributes not in the default_scope" do
    mailing_list = MailingList.create(name: "Foo")
    expect(mailing_list.reload.versions.count).to eq 1
    mailing_list.update(name: "Bar")
    expect(mailing_list.reload.versions.count).to eq 2
  end


  it "issue changing attribute within the default_scope" do
    mailing_list = MailingList.create(name: "Nope")
    expect(mailing_list.reload.versions.count).to eq 1
    mailing_list.update(active: false)
    expect(mailing_list.reload.versions.count).to eq 2
  end

end


# STEP SIX: Run this script using `ruby my_bug_report.rb`