147 files changed, 596 insertions, 87 deletions

diff --git a/activerecord/test/models/account.rb b/activerecord/test/models/account.rb
new file mode 100644
index 0000000000..0c3cd45a81
--- /dev/null
+++ b/activerecord/test/models/account.rb
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+class Account < ActiveRecord::Base
+  belongs_to :firm, class_name: "Company"
+  belongs_to :unautosaved_firm, foreign_key: "firm_id", class_name: "Firm", autosave: false
+
+  alias_attribute :available_credit, :credit_limit
+
+  def self.destroyed_account_ids
+    @destroyed_account_ids ||= Hash.new { |h, k| h[k] = [] }
+  end
+
+  # Test private kernel method through collection proxy using has_many.
+  def self.open
+    where("firm_name = ?", "37signals")
+  end
+
+  before_destroy do |account|
+    if account.firm
+      Account.destroyed_account_ids[account.firm.id] << account.id
+    end
+  end
+
+  validate :check_empty_credit_limit
+
+  private
+    def check_empty_credit_limit
+      errors.add("credit_limit", :blank) if credit_limit.blank?
+    end
+
+    def private_method
+      "Sir, yes sir!"
+    end
+end
diff --git a/activerecord/test/models/admin.rb b/activerecord/test/models/admin.rb
index bc3ce23447..a40b5a33b2 100644
--- a/activerecord/test/models/admin.rb
+++ b/activerecord/test/models/admin.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Admin
   def self.table_name_prefix
     "admin_"
diff --git a/activerecord/test/models/admin/account.rb b/activerecord/test/models/admin/account.rb
index bd23192d20..41fe2d782b 100644
--- a/activerecord/test/models/admin/account.rb
+++ b/activerecord/test/models/admin/account.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::Account < ActiveRecord::Base
   has_many :users
 end
diff --git a/activerecord/test/models/admin/randomly_named_c1.rb b/activerecord/test/models/admin/randomly_named_c1.rb
index b64ae7fc41..d89b8dd293 100644
--- a/activerecord/test/models/admin/randomly_named_c1.rb
+++ b/activerecord/test/models/admin/randomly_named_c1.rb
@@ -1,7 +1,9 @@
-class Admin::ClassNameThatDoesNotFollowCONVENTIONS1 < ActiveRecord::Base

-  self.table_name = :randomly_named_table2

-end

-

-class Admin::ClassNameThatDoesNotFollowCONVENTIONS2 < ActiveRecord::Base

-  self.table_name = :randomly_named_table3

-end

+# frozen_string_literal: true
+
+class Admin::ClassNameThatDoesNotFollowCONVENTIONS1 < ActiveRecord::Base
+  self.table_name = :randomly_named_table2
+end
+
+class Admin::ClassNameThatDoesNotFollowCONVENTIONS2 < ActiveRecord::Base
+  self.table_name = :randomly_named_table3
+end
diff --git a/activerecord/test/models/admin/user.rb b/activerecord/test/models/admin/user.rb
index a76e4b6795..691f9f11be 100644
--- a/activerecord/test/models/admin/user.rb
+++ b/activerecord/test/models/admin/user.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::User < ActiveRecord::Base
   class Coder
     def initialize(default = {})
@@ -17,6 +19,12 @@ class Admin::User < ActiveRecord::Base
   store :params, accessors: [ :token ], coder: YAML
   store :settings, accessors: [ :color, :homepage ]
   store_accessor :settings, :favorite_food
+  store :parent, accessors: [:birthday, :name], prefix: true
+  store :spouse, accessors: [:birthday], prefix: :partner
+  store_accessor :spouse, :name, prefix: :partner
+  store :configs, accessors: [ :secret_question ]
+  store :configs, accessors: [ :two_factor_auth ], suffix: true
+  store_accessor :configs, :login_retry, suffix: :config
   store :preferences, accessors: [ :remember_login ]
   store :json_data, accessors: [ :height, :weight ], coder: Coder.new
   store :json_data_empty, accessors: [ :is_a_good_guy ], coder: Coder.new
diff --git a/activerecord/test/models/aircraft.rb b/activerecord/test/models/aircraft.rb
index ebd42ff824..4fdea46cf7 100644
--- a/activerecord/test/models/aircraft.rb
+++ b/activerecord/test/models/aircraft.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Aircraft < ActiveRecord::Base
   self.pluralize_table_names = false
   has_many :engines, foreign_key: "car_id"
diff --git a/activerecord/test/models/arunit2_model.rb b/activerecord/test/models/arunit2_model.rb
index 04b8b15d3d..5b0da8a249 100644
--- a/activerecord/test/models/arunit2_model.rb
+++ b/activerecord/test/models/arunit2_model.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ARUnit2Model < ActiveRecord::Base
   self.abstract_class = true
 end
diff --git a/activerecord/test/models/author.rb b/activerecord/test/models/author.rb
index fab613afd1..75932c7eb6 100644
--- a/activerecord/test/models/author.rb
+++ b/activerecord/test/models/author.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Author < ActiveRecord::Base
   has_many :posts
   has_many :serialized_posts
@@ -6,6 +8,7 @@ class Author < ActiveRecord::Base
   has_many :posts_with_comments, -> { includes(:comments) }, class_name: "Post"
   has_many :popular_grouped_posts, -> { includes(:comments).group("type").having("SUM(comments_count) > 1").select("type") }, class_name: "Post"
   has_many :posts_with_comments_sorted_by_comment_id, -> { includes(:comments).order("comments.id") }, class_name: "Post"
+  has_many :posts_sorted_by_id, -> { order(:id) }, class_name: "Post"
   has_many :posts_sorted_by_id_limited, -> { order("posts.id").limit(1) }, class_name: "Post"
   has_many :posts_with_categories, -> { includes(:categories) }, class_name: "Post"
   has_many :posts_with_comments_and_categories, -> { includes(:comments, :categories).order("posts.id") }, class_name: "Post"
@@ -19,7 +22,8 @@ class Author < ActiveRecord::Base
   end
   has_many :comments_containing_the_letter_e, through: :posts, source: :comments
   has_many :comments_with_order_and_conditions, -> { order("comments.body").where("comments.body like 'Thank%'") }, through: :posts, source: :comments
-  has_many :comments_with_include, -> { includes(:post) }, through: :posts, source: :comments
+  has_many :comments_with_include, -> { includes(:post).where(posts: { type: "Post" }) }, through: :posts, source: :comments
+  has_many :comments_for_first_author, -> { for_first_author }, through: :posts, source: :comments
 
   has_many :first_posts
   has_many :comments_on_first_posts, -> { order("posts.id desc, comments.id asc") }, through: :first_posts, source: :comments
@@ -37,7 +41,8 @@ class Author < ActiveRecord::Base
            -> { where(title: "Welcome to the weblog").where(Post.arel_table[:comments_count].gt(0)) },
            class_name: "Post"
 
-  has_many :comments_desc, -> { order("comments.id DESC") }, through: :posts, source: :comments
+  has_many :comments_desc, -> { order("comments.id DESC") }, through: :posts_sorted_by_id, source: :comments
+  has_many :unordered_comments, -> { unscope(:order).distinct }, through: :posts_sorted_by_id_limited, source: :comments
   has_many :funky_comments, through: :posts, source: :comments
   has_many :ordered_uniq_comments, -> { distinct.order("comments.id") }, through: :posts, source: :comments
   has_many :ordered_uniq_comments_desc, -> { distinct.order("comments.id DESC") }, through: :posts, source: :comments
@@ -76,7 +81,7 @@ class Author < ActiveRecord::Base
            after_add: [:log_after_adding,  Proc.new { |o, r| o.post_log << "after_adding_proc#{r.id || '<new>'}" }]
   has_many :unchangeable_posts, class_name: "Post", before_add: :raise_exception, after_add: :log_after_adding
 
-  has_many :categorizations
+  has_many :categorizations, -> {}
   has_many :categories, through: :categorizations
   has_many :named_categories, through: :categorizations
 
@@ -84,6 +89,9 @@ class Author < ActiveRecord::Base
   has_many :special_categories, through: :special_categorizations, source: :category
   has_one  :special_category,   through: :special_categorizations, source: :category
 
+  has_many :special_categories_with_conditions, -> { where(categorizations: { special: true }) }, through: :categorizations, source: :category
+  has_many :nonspecial_categories_with_conditions, -> { where(categorizations: { special: false }) }, through: :categorizations, source: :category
+
   has_many :categories_like_general, -> { where(name: "General") }, through: :categorizations, source: :category, class_name: "Category"
 
   has_many :categorized_posts, through: :categorizations, source: :post
@@ -97,15 +105,18 @@ class Author < ActiveRecord::Base
   has_many :taggings,        through: :posts, source: :taggings
   has_many :taggings_2,      through: :posts, source: :tagging
   has_many :tags,            through: :posts
+  has_many :ordered_tags,    through: :posts
   has_many :post_categories, through: :posts, source: :categories
   has_many :tagging_tags,    through: :taggings, source: :tag
 
   has_many :similar_posts, -> { distinct }, through: :tags, source: :tagged_posts
+  has_many :ordered_posts, -> { distinct }, through: :ordered_tags, source: :tagged_posts
   has_many :distinct_tags, -> { select("DISTINCT tags.*").order("tags.name") }, through: :posts, source: :tags
 
   has_many :tags_with_primary_key, through: :posts
 
   has_many :books
+  has_many :unpublished_books, -> { where(status: [:proposed, :written]) }, class_name: "Book"
   has_many :subscriptions,        through: :books
   has_many :subscribers, -> { order("subscribers.nick") }, through: :subscriptions
   has_many :distinct_subscribers, -> { select("DISTINCT subscribers.*").order("subscribers.nick") }, through: :subscriptions, source: :subscriber
@@ -151,6 +162,9 @@ class Author < ActiveRecord::Base
     def extension_method; end
   end
 
+  has_many :top_posts, -> { order(id: :asc) }, class_name: "Post"
+  has_many :other_top_posts, -> { order(id: :asc) }, class_name: "Post"
+
   attr_accessor :post_log
   after_initialize :set_post_log
 
diff --git a/activerecord/test/models/auto_id.rb b/activerecord/test/models/auto_id.rb
index 82c6544bd5..fd672603bb 100644
--- a/activerecord/test/models/auto_id.rb
+++ b/activerecord/test/models/auto_id.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class AutoId < ActiveRecord::Base
   self.table_name = "auto_id_tests"
   self.primary_key = "auto_id"
diff --git a/activerecord/test/models/autoloadable/extra_firm.rb b/activerecord/test/models/autoloadable/extra_firm.rb
index 5578ba0d9b..c46e34c101 100644
--- a/activerecord/test/models/autoloadable/extra_firm.rb
+++ b/activerecord/test/models/autoloadable/extra_firm.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class ExtraFirm < Company
 end
diff --git a/activerecord/test/models/binary.rb b/activerecord/test/models/binary.rb
index 39b2f5090a..b93f87519f 100644
--- a/activerecord/test/models/binary.rb
+++ b/activerecord/test/models/binary.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class Binary < ActiveRecord::Base
 end
diff --git a/activerecord/test/models/bird.rb b/activerecord/test/models/bird.rb
index 24b839135d..be08636ac6 100644
--- a/activerecord/test/models/bird.rb
+++ b/activerecord/test/models/bird.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Bird < ActiveRecord::Base
   belongs_to :pirate
   validates_presence_of :name
diff --git a/activerecord/test/models/book.rb b/activerecord/test/models/book.rb
index 17bf3fbcb4..afdda1a81e 100644
--- a/activerecord/test/models/book.rb
+++ b/activerecord/test/models/book.rb
@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 class Book < ActiveRecord::Base
-  has_many :authors
+  belongs_to :author
 
   has_many :citations, foreign_key: "book1_id"
   has_many :references, -> { distinct }, through: :citations, source: :reference_of
@@ -8,7 +10,7 @@ class Book < ActiveRecord::Base
   has_many :subscribers, through: :subscriptions
 
   enum status: [:proposed, :written, :published]
-  enum read_status: { unread: 0, reading: 2, read: 3 }
+  enum read_status: { unread: 0, reading: 2, read: 3, forgotten: nil }
   enum nullable_status: [:single, :married]
   enum language: [:english, :spanish, :french], _prefix: :in
   enum author_visibility: [:visible, :invisible], _prefix: true
diff --git a/activerecord/test/models/boolean.rb b/activerecord/test/models/boolean.rb
index 0da228aac2..bee757fb9c 100644
--- a/activerecord/test/models/boolean.rb
+++ b/activerecord/test/models/boolean.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Boolean < ActiveRecord::Base
   def has_fun
     super
diff --git a/activerecord/test/models/bulb.rb b/activerecord/test/models/bulb.rb
index 113d21cb84..ab92f7025d 100644
--- a/activerecord/test/models/bulb.rb
+++ b/activerecord/test/models/bulb.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Bulb < ActiveRecord::Base
   default_scope { where(name: "defaulty") }
   belongs_to :car, touch: true
diff --git a/activerecord/test/models/cake_designer.rb b/activerecord/test/models/cake_designer.rb
index 9c57ef573a..0b2a00edfd 100644
--- a/activerecord/test/models/cake_designer.rb
+++ b/activerecord/test/models/cake_designer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CakeDesigner < ActiveRecord::Base
   has_one :chef, as: :employable
 end
diff --git a/activerecord/test/models/car.rb b/activerecord/test/models/car.rb
index 92bff7ff96..8614926626 100644
--- a/activerecord/test/models/car.rb
+++ b/activerecord/test/models/car.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Car < ActiveRecord::Base
   has_many :bulbs
   has_many :all_bulbs, -> { unscope where: :name }, class_name: "Bulb"
@@ -18,6 +20,8 @@ class Car < ActiveRecord::Base
   scope :incl_engines, -> { includes(:engines) }
 
   scope :order_using_new_style,  -> { order("name asc") }
+
+  attribute :wheels_owned_at, :datetime, default: -> { Time.now }
 end
 
 class CoolCar < Car
diff --git a/activerecord/test/models/carrier.rb b/activerecord/test/models/carrier.rb
index 230be118c3..995a9d3bef 100644
--- a/activerecord/test/models/carrier.rb
+++ b/activerecord/test/models/carrier.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class Carrier < ActiveRecord::Base
 end
diff --git a/activerecord/test/models/cat.rb b/activerecord/test/models/cat.rb
index dfdde18641..43013964b6 100644
--- a/activerecord/test/models/cat.rb
+++ b/activerecord/test/models/cat.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Cat < ActiveRecord::Base
   self.abstract_class = true
 
diff --git a/activerecord/test/models/categorization.rb b/activerecord/test/models/categorization.rb
index b99383d0b1..68b0ea90d3 100644
--- a/activerecord/test/models/categorization.rb
+++ b/activerecord/test/models/categorization.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Categorization < ActiveRecord::Base
   belongs_to :post
   belongs_to :category, counter_cache: true
diff --git a/activerecord/test/models/category.rb b/activerecord/test/models/category.rb
index e8654dca01..2ccc00bed9 100644
--- a/activerecord/test/models/category.rb
+++ b/activerecord/test/models/category.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Category < ActiveRecord::Base
   has_and_belongs_to_many :posts
   has_and_belongs_to_many :special_posts, class_name: "Post"
@@ -29,6 +31,15 @@ class Category < ActiveRecord::Base
   has_many :authors_with_select, -> { select "authors.*, categorizations.post_id" }, through: :categorizations, source: :author
 
   scope :general, -> { where(name: "General") }
+
+  # Should be delegated `ast` and `locked` to `arel`.
+  def self.ast
+    raise
+  end
+
+  def self.locked
+    raise
+  end
 end
 
 class SpecialCategory < Category
diff --git a/activerecord/test/models/chef.rb b/activerecord/test/models/chef.rb
index 9d3dd01016..ff528644bc 100644
--- a/activerecord/test/models/chef.rb
+++ b/activerecord/test/models/chef.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Chef < ActiveRecord::Base
   belongs_to :employable, polymorphic: true
   has_many :recipes
diff --git a/activerecord/test/models/citation.rb b/activerecord/test/models/citation.rb
index 7d06387f56..3d786f27eb 100644
--- a/activerecord/test/models/citation.rb
+++ b/activerecord/test/models/citation.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Citation < ActiveRecord::Base
   belongs_to :reference_of, class_name: "Book", foreign_key: :book2_id
 end
diff --git a/activerecord/test/models/club.rb b/activerecord/test/models/club.rb
index 49d7b24a3b..2006e05fcf 100644
--- a/activerecord/test/models/club.rb
+++ b/activerecord/test/models/club.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Club < ActiveRecord::Base
   has_one :membership
   has_many :memberships, inverse_of: false
@@ -8,6 +10,8 @@ class Club < ActiveRecord::Base
 
   has_many :favourites, -> { where(memberships: { favourite: true }) }, through: :memberships, source: :member
 
+  scope :general, -> { left_joins(:category).where(categories: { name: "General" }) }
+
   private
 
     def private_method
diff --git a/activerecord/test/models/college.rb b/activerecord/test/models/college.rb
index c9dbe1ecc2..52017dda42 100644
--- a/activerecord/test/models/college.rb
+++ b/activerecord/test/models/college.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency "models/arunit2_model"
 require "active_support/core_ext/object/with_options"
 
diff --git a/activerecord/test/models/column.rb b/activerecord/test/models/column.rb
index 499358b4cf..d3cd419a00 100644
--- a/activerecord/test/models/column.rb
+++ b/activerecord/test/models/column.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Column < ActiveRecord::Base
   belongs_to :record
 end
diff --git a/activerecord/test/models/column_name.rb b/activerecord/test/models/column_name.rb
index 460eb4fe20..c6047c507b 100644
--- a/activerecord/test/models/column_name.rb
+++ b/activerecord/test/models/column_name.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ColumnName < ActiveRecord::Base
   self.table_name = "colnametests"
 end
diff --git a/activerecord/test/models/comment.rb b/activerecord/test/models/comment.rb
index a4b81d56e0..f0f0576709 100644
--- a/activerecord/test/models/comment.rb
+++ b/activerecord/test/models/comment.rb
@@ -1,3 +1,8 @@
+# frozen_string_literal: true
+
+# `counter_cache` requires association class before `attr_readonly`.
+class Post < ActiveRecord::Base; end
+
 class Comment < ActiveRecord::Base
   scope :limit_by, lambda { |l| limit(l) }
   scope :containing_the_letter_e, -> { where("comments.body LIKE '%e%'") }
@@ -9,7 +14,6 @@ class Comment < ActiveRecord::Base
   belongs_to :post, counter_cache: true
   belongs_to :author,   polymorphic: true
   belongs_to :resource, polymorphic: true
-  belongs_to :developer
 
   has_many :ratings
 
@@ -19,6 +23,23 @@ class Comment < ActiveRecord::Base
   has_many :children, class_name: "Comment", foreign_key: :parent_id
   belongs_to :parent, class_name: "Comment", counter_cache: :children_count
 
+  class ::OopsError < RuntimeError; end
+
+  module OopsExtension
+    def destroy_all(*)
+      raise OopsError
+    end
+  end
+
+  default_scope { extending OopsExtension }
+
+  scope :oops_comments, -> { extending OopsExtension }
+
+  # Should not be called if extending modules that having the method exists on an association.
+  def self.greeting
+    raise
+  end
+
   def self.what_are_you
     "a comment..."
   end
@@ -38,6 +59,11 @@ class Comment < ActiveRecord::Base
 end
 
 class SpecialComment < Comment
+  default_scope { where(deleted_at: nil) }
+
+  def self.what_are_you
+    "a special comment..."
+  end
 end
 
 class SubSpecialComment < SpecialComment
@@ -50,7 +76,7 @@ class CommentThatAutomaticallyAltersPostBody < Comment
   belongs_to :post, class_name: "PostThatLoadsCommentsInAnAfterSaveHook", foreign_key: :post_id
 
   after_save do |comment|
-    comment.post.update_attributes(body: "Automatically altered")
+    comment.post.update(body: "Automatically altered")
   end
 end
 
@@ -58,3 +84,9 @@ class CommentWithDefaultScopeReferencesAssociation < Comment
   default_scope -> { includes(:developer).order("developers.name").references(:developer) }
   belongs_to :developer
 end
+
+class CommentWithAfterCreateUpdate < Comment
+  after_create do
+    update(body: "bar")
+  end
+end
diff --git a/activerecord/test/models/company.rb b/activerecord/test/models/company.rb
index 20e37710e7..485b35d58b 100644
--- a/activerecord/test/models/company.rb
+++ b/activerecord/test/models/company.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class AbstractCompany < ActiveRecord::Base
   self.abstract_class = true
 end
@@ -85,6 +87,8 @@ class Firm < Company
 
   has_many :association_with_references, -> { references(:foo) }, class_name: "Client"
 
+  has_many :developers_with_select, -> { select("id, name, first_name") }, class_name: "Developer"
+
   has_one :lead_developer, class_name: "Developer"
   has_many :projects
 
@@ -141,6 +145,21 @@ class Client < Company
     raise RaisedOnSave if raise_on_save
   end
 
+  attr_accessor :throw_on_save
+  before_save do
+    throw :abort if throw_on_save
+  end
+
+  attr_accessor :rollback_on_save
+  after_save do
+    raise ActiveRecord::Rollback if rollback_on_save
+  end
+
+  attr_accessor :rollback_on_create_called
+  after_rollback(on: :create) do |client|
+    client.rollback_on_create_called = true
+  end
+
   class RaisedOnDestroy < RuntimeError; end
   attr_accessor :raise_on_destroy
   before_destroy do
@@ -170,19 +189,12 @@ class Client < Company
 
   def overwrite_to_raise
   end
-
-  class << self
-    private
-
-    def private_method
-      "darkness"
-    end
-  end
 end
 
 class ExclusivelyDependentFirm < Company
   has_one :account, foreign_key: "firm_id", dependent: :delete
   has_many :dependent_sanitized_conditional_clients_of_firm, -> { order("id").where("name = 'BigShot Inc.'") }, foreign_key: "client_of", class_name: "Client", dependent: :delete_all
+  has_many :dependent_hash_conditional_clients_of_firm, -> { order("id").where(name: "BigShot Inc.") }, foreign_key: "client_of", class_name: "Client", dependent: :delete_all
   has_many :dependent_conditional_clients_of_firm, -> { order("id").where("name = ?", "BigShot Inc.") }, foreign_key: "client_of", class_name: "Client", dependent: :delete_all
 end
 
@@ -192,37 +204,12 @@ end
 class VerySpecialClient < SpecialClient
 end
 
-class Account < ActiveRecord::Base
-  belongs_to :firm, class_name: "Company"
-  belongs_to :unautosaved_firm, foreign_key: "firm_id", class_name: "Firm", autosave: false
+class NewlyContractedCompany < Company
+  has_many :new_contracts, foreign_key: "company_id"
 
-  alias_attribute :available_credit, :credit_limit
-
-  def self.destroyed_account_ids
-    @destroyed_account_ids ||= Hash.new { |h, k| h[k] = [] }
-  end
-
-  # Test private kernel method through collection proxy using has_many.
-  def self.open
-    where("firm_name = ?", "37signals")
-  end
-
-  before_destroy do |account|
-    if account.firm
-      Account.destroyed_account_ids[account.firm.id] << account.id
-    end
-    true
+  before_save do
+    self.new_contracts << NewContract.new
   end
-
-  validate :check_empty_credit_limit
-
-  private
-
-    def check_empty_credit_limit
-      errors.add("credit_limit", :blank) if credit_limit.blank?
-    end
-
-    def private_method
-      "Sir, yes sir!"
-    end
 end
+
+require "models/account"
diff --git a/activerecord/test/models/company_in_module.rb b/activerecord/test/models/company_in_module.rb
index 0782c1eff4..52b7e06a63 100644
--- a/activerecord/test/models/company_in_module.rb
+++ b/activerecord/test/models/company_in_module.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "active_support/core_ext/object/with_options"
 
 module MyApplication
diff --git a/activerecord/test/models/computer.rb b/activerecord/test/models/computer.rb
index 1c9856e1af..582b4a38b5 100644
--- a/activerecord/test/models/computer.rb
+++ b/activerecord/test/models/computer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Computer < ActiveRecord::Base
   belongs_to :developer, foreign_key: "developer"
 end
diff --git a/activerecord/test/models/contact.rb b/activerecord/test/models/contact.rb
index 47bbbbfd8b..6e02ff199b 100644
--- a/activerecord/test/models/contact.rb
+++ b/activerecord/test/models/contact.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ContactFakeColumns
   def self.extended(base)
     base.class_eval do
diff --git a/activerecord/test/models/content.rb b/activerecord/test/models/content.rb
index 68db2127d8..14bbee53d8 100644
--- a/activerecord/test/models/content.rb
+++ b/activerecord/test/models/content.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Content < ActiveRecord::Base
   self.table_name = "content"
   has_one :content_position, dependent: :destroy
diff --git a/activerecord/test/models/contract.rb b/activerecord/test/models/contract.rb
index 32bd581377..3f663375c4 100644
--- a/activerecord/test/models/contract.rb
+++ b/activerecord/test/models/contract.rb
@@ -1,6 +1,8 @@
+# frozen_string_literal: true
+
 class Contract < ActiveRecord::Base
   belongs_to :company
-  belongs_to :developer
+  belongs_to :developer, primary_key: :id
   belongs_to :firm, foreign_key: "company_id"
 
   before_save :hi
@@ -18,3 +20,7 @@ class Contract < ActiveRecord::Base
     @bye_count += 1
   end
 end
+
+class NewContract < Contract
+  validates :company_id, presence: true
+end
diff --git a/activerecord/test/models/country.rb b/activerecord/test/models/country.rb
index 7912719ddd..0c84a40de2 100644
--- a/activerecord/test/models/country.rb
+++ b/activerecord/test/models/country.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Country < ActiveRecord::Base
   self.primary_key = :country_id
 
diff --git a/activerecord/test/models/course.rb b/activerecord/test/models/course.rb
index 348f2bf1e0..4f346124ea 100644
--- a/activerecord/test/models/course.rb
+++ b/activerecord/test/models/course.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency "models/arunit2_model"
 
 class Course < ARUnit2Model
diff --git a/activerecord/test/models/customer.rb b/activerecord/test/models/customer.rb
index 3d40cb1ace..bc501a5ce0 100644
--- a/activerecord/test/models/customer.rb
+++ b/activerecord/test/models/customer.rb
@@ -1,8 +1,10 @@
+# frozen_string_literal: true
+
 class Customer < ActiveRecord::Base
   cattr_accessor :gps_conversion_was_run
 
   composed_of :address, mapping: [ %w(address_street street), %w(address_city city), %w(address_country country) ], allow_nil: true
-  composed_of :balance, class_name: "Money", mapping: %w(balance amount), converter: Proc.new(&:to_money)
+  composed_of :balance, class_name: "Money", mapping: %w(balance amount)
   composed_of :gps_location, allow_nil: true
   composed_of :non_blank_gps_location, class_name: "GpsLocation", allow_nil: true, mapping: %w(gps_location gps_location),
               converter: lambda { |gps| self.gps_conversion_was_run = true; gps.blank? ? nil : GpsLocation.new(gps) }
diff --git a/activerecord/test/models/customer_carrier.rb b/activerecord/test/models/customer_carrier.rb
index 37186903ff..6cb9d5239d 100644
--- a/activerecord/test/models/customer_carrier.rb
+++ b/activerecord/test/models/customer_carrier.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CustomerCarrier < ActiveRecord::Base
   cattr_accessor :current_customer
 
diff --git a/activerecord/test/models/dashboard.rb b/activerecord/test/models/dashboard.rb
index 1b3b54545f..d25ceeafb1 100644
--- a/activerecord/test/models/dashboard.rb
+++ b/activerecord/test/models/dashboard.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Dashboard < ActiveRecord::Base
   self.primary_key = :dashboard_id
 end
diff --git a/activerecord/test/models/default.rb b/activerecord/test/models/default.rb
index 887e9cc999..90f1046d87 100644
--- a/activerecord/test/models/default.rb
+++ b/activerecord/test/models/default.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class Default < ActiveRecord::Base
 end
diff --git a/activerecord/test/models/department.rb b/activerecord/test/models/department.rb
index 08004a0ed3..868b9bf4bf 100644
--- a/activerecord/test/models/department.rb
+++ b/activerecord/test/models/department.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Department < ActiveRecord::Base
   has_many :chefs
   belongs_to :hotel
diff --git a/activerecord/test/models/developer.rb b/activerecord/test/models/developer.rb
index 654830ba11..8881c69368 100644
--- a/activerecord/test/models/developer.rb
+++ b/activerecord/test/models/developer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "ostruct"
 
 module DeveloperProjectsAssociationExtension2
@@ -85,6 +87,17 @@ class Developer < ActiveRecord::Base
   private :track_instance_count
 end
 
+class SubDeveloper < Developer
+end
+
+class SymbolIgnoredDeveloper < ActiveRecord::Base
+  self.table_name = "developers"
+  self.ignored_columns = [:first_name, :last_name]
+
+  attr_accessor :last_name
+  define_attribute_method "last_name"
+end
+
 class AuditLog < ActiveRecord::Base
   belongs_to :developer, validate: true
   belongs_to :unvalidated_developer, class_name: "Developer"
diff --git a/activerecord/test/models/dog.rb b/activerecord/test/models/dog.rb
index b02b8447b8..75d284ac25 100644
--- a/activerecord/test/models/dog.rb
+++ b/activerecord/test/models/dog.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Dog < ActiveRecord::Base
   belongs_to :breeder, class_name: "DogLover", counter_cache: :bred_dogs_count
   belongs_to :trainer, class_name: "DogLover", counter_cache: :trained_dogs_count
diff --git a/activerecord/test/models/dog_lover.rb b/activerecord/test/models/dog_lover.rb
index 2c5be94aea..aabe914f77 100644
--- a/activerecord/test/models/dog_lover.rb
+++ b/activerecord/test/models/dog_lover.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class DogLover < ActiveRecord::Base
   has_many :trained_dogs, class_name: "Dog", foreign_key: :trainer_id, dependent: :destroy
   has_many :bred_dogs, class_name: "Dog", foreign_key: :breeder_id
diff --git a/activerecord/test/models/doubloon.rb b/activerecord/test/models/doubloon.rb
index 7272504666..febadc3a5a 100644
--- a/activerecord/test/models/doubloon.rb
+++ b/activerecord/test/models/doubloon.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class AbstractDoubloon < ActiveRecord::Base
   # This has functionality that might be shared by multiple classes.
 
diff --git a/activerecord/test/models/drink_designer.rb b/activerecord/test/models/drink_designer.rb
index 2db968ef11..eb6701b84e 100644
--- a/activerecord/test/models/drink_designer.rb
+++ b/activerecord/test/models/drink_designer.rb
@@ -1,3 +1,8 @@
+# frozen_string_literal: true
+
 class DrinkDesigner < ActiveRecord::Base
   has_one :chef, as: :employable
 end
+
+class MocktailDesigner < DrinkDesigner
+end
diff --git a/activerecord/test/models/edge.rb b/activerecord/test/models/edge.rb
index e61d25c9bc..a04ab103de 100644
--- a/activerecord/test/models/edge.rb
+++ b/activerecord/test/models/edge.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This class models an edge in a directed graph.
 class Edge < ActiveRecord::Base
   belongs_to :source, class_name: "Vertex", foreign_key: "source_id"
diff --git a/activerecord/test/models/electron.rb b/activerecord/test/models/electron.rb
index 6fc270673f..902006b314 100644
--- a/activerecord/test/models/electron.rb
+++ b/activerecord/test/models/electron.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Electron < ActiveRecord::Base
   belongs_to :molecule
 
diff --git a/activerecord/test/models/engine.rb b/activerecord/test/models/engine.rb
index eada171f6a..396a52b3b9 100644
--- a/activerecord/test/models/engine.rb
+++ b/activerecord/test/models/engine.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Engine < ActiveRecord::Base
   belongs_to :my_car, class_name: "Car", foreign_key: "car_id",  counter_cache: :engines_count
 end
diff --git a/activerecord/test/models/entrant.rb b/activerecord/test/models/entrant.rb
index 4682ce48c8..2c086e451f 100644
--- a/activerecord/test/models/entrant.rb
+++ b/activerecord/test/models/entrant.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Entrant < ActiveRecord::Base
   belongs_to :course
 end
diff --git a/activerecord/test/models/essay.rb b/activerecord/test/models/essay.rb
index 13267fbc21..e59db4d877 100644
--- a/activerecord/test/models/essay.rb
+++ b/activerecord/test/models/essay.rb
@@ -1,4 +1,7 @@
+# frozen_string_literal: true
+
 class Essay < ActiveRecord::Base
+  belongs_to :author
   belongs_to :writer, primary_key: :name, polymorphic: true
   belongs_to :category, primary_key: :name
   has_one :owner, primary_key: :name
diff --git a/activerecord/test/models/event.rb b/activerecord/test/models/event.rb
index 365ab32b0b..a7cdc39e5c 100644
--- a/activerecord/test/models/event.rb
+++ b/activerecord/test/models/event.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Event < ActiveRecord::Base
   validates_uniqueness_of :title
 end
diff --git a/activerecord/test/models/eye.rb b/activerecord/test/models/eye.rb
index f53c34e4b1..f3608b62ef 100644
--- a/activerecord/test/models/eye.rb
+++ b/activerecord/test/models/eye.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Eye < ActiveRecord::Base
   attr_reader :after_create_callbacks_stack
   attr_reader :after_update_callbacks_stack
diff --git a/activerecord/test/models/face.rb b/activerecord/test/models/face.rb
index 5913bfa969..e900fd40fb 100644
--- a/activerecord/test/models/face.rb
+++ b/activerecord/test/models/face.rb
@@ -1,9 +1,16 @@
+# frozen_string_literal: true
+
 class Face < ActiveRecord::Base
   belongs_to :man, inverse_of: :face
+  belongs_to :human, polymorphic: true
   belongs_to :polymorphic_man, polymorphic: true, inverse_of: :polymorphic_face
   # Oracle identifier length is limited to 30 bytes or less, `polymorphic` renamed `poly`
   belongs_to :poly_man_without_inverse, polymorphic: true
   # These is a "broken" inverse_of for the purposes of testing
   belongs_to :horrible_man, class_name: "Man", inverse_of: :horrible_face
   belongs_to :horrible_polymorphic_man, polymorphic: true, inverse_of: :horrible_polymorphic_face
+
+  validate do
+    man
+  end
 end
diff --git a/activerecord/test/models/family.rb b/activerecord/test/models/family.rb
index 5ae5a78c95..0713dba1a6 100644
--- a/activerecord/test/models/family.rb
+++ b/activerecord/test/models/family.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Family < ActiveRecord::Base
   has_many :family_trees, -> { where(token: nil) }
   has_many :members, through: :family_trees
diff --git a/activerecord/test/models/family_tree.rb b/activerecord/test/models/family_tree.rb
index cd9829fedd..a8ea907c05 100644
--- a/activerecord/test/models/family_tree.rb
+++ b/activerecord/test/models/family_tree.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class FamilyTree < ActiveRecord::Base
   belongs_to :member, class_name: "User", foreign_key: "member_id"
   belongs_to :family
diff --git a/activerecord/test/models/friendship.rb b/activerecord/test/models/friendship.rb
index 578382b494..9f1712a8ec 100644
--- a/activerecord/test/models/friendship.rb
+++ b/activerecord/test/models/friendship.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Friendship < ActiveRecord::Base
   belongs_to :friend, class_name: "Person"
   # friend_too exists to test a bug, and probably shouldn't be used elsewhere
diff --git a/activerecord/test/models/frog.rb b/activerecord/test/models/frog.rb
new file mode 100644
index 0000000000..73601aacdd
--- /dev/null
+++ b/activerecord/test/models/frog.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class Frog < ActiveRecord::Base
+  after_save do
+    with_lock do
+    end
+  end
+end
diff --git a/activerecord/test/models/guid.rb b/activerecord/test/models/guid.rb
index 05653ba498..ec71c37690 100644
--- a/activerecord/test/models/guid.rb
+++ b/activerecord/test/models/guid.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class Guid < ActiveRecord::Base
 end
diff --git a/activerecord/test/models/guitar.rb b/activerecord/test/models/guitar.rb
index cd068ff53d..649b998665 100644
--- a/activerecord/test/models/guitar.rb
+++ b/activerecord/test/models/guitar.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Guitar < ActiveRecord::Base
   has_many :tuning_pegs, index_errors: true
   accepts_nested_attributes_for :tuning_pegs
diff --git a/activerecord/test/models/hotel.rb b/activerecord/test/models/hotel.rb
index 7bc717c891..1a433c3cab 100644
--- a/activerecord/test/models/hotel.rb
+++ b/activerecord/test/models/hotel.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Hotel < ActiveRecord::Base
   has_many :departments
   has_many :chefs, through: :departments
diff --git a/activerecord/test/models/image.rb b/activerecord/test/models/image.rb
index 7ae8e4a7f6..b4808293cc 100644
--- a/activerecord/test/models/image.rb
+++ b/activerecord/test/models/image.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Image < ActiveRecord::Base
   belongs_to :imageable, foreign_key: :imageable_identifier, foreign_type: :imageable_class
 end
diff --git a/activerecord/test/models/interest.rb b/activerecord/test/models/interest.rb
index ec79416ee7..899b8f9b9d 100644
--- a/activerecord/test/models/interest.rb
+++ b/activerecord/test/models/interest.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Interest < ActiveRecord::Base
   belongs_to :man, inverse_of: :interests
   belongs_to :polymorphic_man, polymorphic: true, inverse_of: :polymorphic_interests
diff --git a/activerecord/test/models/invoice.rb b/activerecord/test/models/invoice.rb
index 4be5a00193..1851792ed5 100644
--- a/activerecord/test/models/invoice.rb
+++ b/activerecord/test/models/invoice.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Invoice < ActiveRecord::Base
   has_many :line_items, autosave: true
   before_save { |record| record.balance = record.line_items.map(&:amount).sum }
diff --git a/activerecord/test/models/item.rb b/activerecord/test/models/item.rb
index 336fb1769a..8d079d56e6 100644
--- a/activerecord/test/models/item.rb
+++ b/activerecord/test/models/item.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class AbstractItem < ActiveRecord::Base
   self.abstract_class = true
   has_one :tagging, as: :taggable
diff --git a/activerecord/test/models/job.rb b/activerecord/test/models/job.rb
index bbaef2792c..52817a8435 100644
--- a/activerecord/test/models/job.rb
+++ b/activerecord/test/models/job.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Job < ActiveRecord::Base
   has_many :references
   has_many :people, through: :references
diff --git a/activerecord/test/models/joke.rb b/activerecord/test/models/joke.rb
index eeb5818a1f..436ffb6471 100644
--- a/activerecord/test/models/joke.rb
+++ b/activerecord/test/models/joke.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Joke < ActiveRecord::Base
   self.table_name = "funny_jokes"
 end
diff --git a/activerecord/test/models/keyboard.rb b/activerecord/test/models/keyboard.rb
index bcede53ec9..d200e0fb56 100644
--- a/activerecord/test/models/keyboard.rb
+++ b/activerecord/test/models/keyboard.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Keyboard < ActiveRecord::Base
   self.primary_key = "key_number"
 end
diff --git a/activerecord/test/models/legacy_thing.rb b/activerecord/test/models/legacy_thing.rb
index eead181a0e..e0210c8922 100644
--- a/activerecord/test/models/legacy_thing.rb
+++ b/activerecord/test/models/legacy_thing.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class LegacyThing < ActiveRecord::Base
   self.locking_column = :version
 end
diff --git a/activerecord/test/models/lesson.rb b/activerecord/test/models/lesson.rb
index 4c88153068..e546339689 100644
--- a/activerecord/test/models/lesson.rb
+++ b/activerecord/test/models/lesson.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class LessonError < Exception
 end
 
diff --git a/activerecord/test/models/line_item.rb b/activerecord/test/models/line_item.rb
index 93f7cceb13..3a51cf03b2 100644
--- a/activerecord/test/models/line_item.rb
+++ b/activerecord/test/models/line_item.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class LineItem < ActiveRecord::Base
   belongs_to :invoice, touch: true
 end
diff --git a/activerecord/test/models/liquid.rb b/activerecord/test/models/liquid.rb
index 69d4d7df1a..b2fd305d66 100644
--- a/activerecord/test/models/liquid.rb
+++ b/activerecord/test/models/liquid.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Liquid < ActiveRecord::Base
   self.table_name = :liquid
   has_many :molecules, -> { distinct }
diff --git a/activerecord/test/models/man.rb b/activerecord/test/models/man.rb
index d2436a735c..e26920e951 100644
--- a/activerecord/test/models/man.rb
+++ b/activerecord/test/models/man.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Man < ActiveRecord::Base
   has_one :face, inverse_of: :man
   has_one :polymorphic_face, class_name: "Face", as: :polymorphic_man, inverse_of: :polymorphic_man
@@ -9,3 +11,6 @@ class Man < ActiveRecord::Base
   has_many :secret_interests, class_name: "Interest", inverse_of: :secret_man
   has_one :mixed_case_monkey
 end
+
+class Human < Man
+end
diff --git a/activerecord/test/models/matey.rb b/activerecord/test/models/matey.rb
index 80ee5f47c5..a77ac21e96 100644
--- a/activerecord/test/models/matey.rb
+++ b/activerecord/test/models/matey.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Matey < ActiveRecord::Base
   belongs_to :pirate
   belongs_to :target, class_name: "Pirate"
diff --git a/activerecord/test/models/member.rb b/activerecord/test/models/member.rb
index 36f2461b84..6e33ac0a6d 100644
--- a/activerecord/test/models/member.rb
+++ b/activerecord/test/models/member.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Member < ActiveRecord::Base
   has_one :current_membership
   has_one :selected_membership
@@ -22,14 +24,16 @@ class Member < ActiveRecord::Base
   has_many :organization_member_details_2, through: :organization, source: :member_details
 
   has_one :club_category, through: :club, source: :category
+  has_one :general_club, -> { general }, through: :current_membership, source: :club
 
-  has_many :current_memberships, -> { where favourite: true }
-  has_many :clubs, through: :current_memberships
+  has_many :super_memberships
+  has_many :favourite_memberships, -> { where(favourite: true) }, class_name: "Membership"
+  has_many :clubs, through: :favourite_memberships
 
   has_many :tenant_memberships
   has_many :tenant_clubs, through: :tenant_memberships, class_name: "Club", source: :club
 
-  has_one :club_through_many, through: :current_memberships, source: :club
+  has_one :club_through_many, through: :favourite_memberships, source: :club
 
   belongs_to :admittable, polymorphic: true
   has_one :premium_club, through: :admittable
diff --git a/activerecord/test/models/member_detail.rb b/activerecord/test/models/member_detail.rb
index 157130986c..e121a849d0 100644
--- a/activerecord/test/models/member_detail.rb
+++ b/activerecord/test/models/member_detail.rb
@@ -1,8 +1,11 @@
+# frozen_string_literal: true
+
 class MemberDetail < ActiveRecord::Base
   belongs_to :member, inverse_of: false
   belongs_to :organization
   has_one :member_type, through: :member
   has_one :membership, through: :member
+  has_one :admittable, through: :member, source_type: "Member"
 
   has_many :organization_member_details, through: :organization, source: :member_details
 end
diff --git a/activerecord/test/models/member_type.rb b/activerecord/test/models/member_type.rb
index a13561c72a..b49b168d03 100644
--- a/activerecord/test/models/member_type.rb
+++ b/activerecord/test/models/member_type.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MemberType < ActiveRecord::Base
   has_many :members
 end
diff --git a/activerecord/test/models/membership.rb b/activerecord/test/models/membership.rb
index 2c3ad230a7..09ee7544b3 100644
--- a/activerecord/test/models/membership.rb
+++ b/activerecord/test/models/membership.rb
@@ -1,4 +1,7 @@
+# frozen_string_literal: true
+
 class Membership < ActiveRecord::Base
+  enum type: %i(Membership CurrentMembership SuperMembership SelectedMembership TenantMembership)
   belongs_to :member
   belongs_to :club
 end
diff --git a/activerecord/test/models/mentor.rb b/activerecord/test/models/mentor.rb
index 66504b4e91..2fbb62c435 100644
--- a/activerecord/test/models/mentor.rb
+++ b/activerecord/test/models/mentor.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Mentor < ActiveRecord::Base
   has_many :developers
 end
diff --git a/activerecord/test/models/minimalistic.rb b/activerecord/test/models/minimalistic.rb
index 2e3f8e081a..c67b086853 100644
--- a/activerecord/test/models/minimalistic.rb
+++ b/activerecord/test/models/minimalistic.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class Minimalistic < ActiveRecord::Base
 end
diff --git a/activerecord/test/models/minivan.rb b/activerecord/test/models/minivan.rb
index e9b05dadf2..d9d331798a 100644
--- a/activerecord/test/models/minivan.rb
+++ b/activerecord/test/models/minivan.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Minivan < ActiveRecord::Base
   self.primary_key = :minivan_id
 
diff --git a/activerecord/test/models/mixed_case_monkey.rb b/activerecord/test/models/mixed_case_monkey.rb
index 1c35006665..8e92f68817 100644
--- a/activerecord/test/models/mixed_case_monkey.rb
+++ b/activerecord/test/models/mixed_case_monkey.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MixedCaseMonkey < ActiveRecord::Base
   belongs_to :man
 end
diff --git a/activerecord/test/models/mocktail_designer.rb b/activerecord/test/models/mocktail_designer.rb
deleted file mode 100644
index 77b44651a3..0000000000
--- a/activerecord/test/models/mocktail_designer.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-class MocktailDesigner < DrinkDesigner
-end
diff --git a/activerecord/test/models/molecule.rb b/activerecord/test/models/molecule.rb
index 26870c8f88..7da08a85c4 100644
--- a/activerecord/test/models/molecule.rb
+++ b/activerecord/test/models/molecule.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Molecule < ActiveRecord::Base
   belongs_to :liquid
   has_many :electrons
diff --git a/activerecord/test/models/movie.rb b/activerecord/test/models/movie.rb
index 0302abad1e..fa2ea900c7 100644
--- a/activerecord/test/models/movie.rb
+++ b/activerecord/test/models/movie.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Movie < ActiveRecord::Base
   self.primary_key = "movieid"
 
diff --git a/activerecord/test/models/node.rb b/activerecord/test/models/node.rb
index 459ea8cf95..ae46c76b46 100644
--- a/activerecord/test/models/node.rb
+++ b/activerecord/test/models/node.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Node < ActiveRecord::Base
   belongs_to :tree, touch: true
   belongs_to :parent,   class_name: "Node", touch: true, optional: true
diff --git a/activerecord/test/models/non_primary_key.rb b/activerecord/test/models/non_primary_key.rb
index 1cafb09608..e954375989 100644
--- a/activerecord/test/models/non_primary_key.rb
+++ b/activerecord/test/models/non_primary_key.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class NonPrimaryKey < ActiveRecord::Base
 end
diff --git a/activerecord/test/models/notification.rb b/activerecord/test/models/notification.rb
index 82edc64b68..3f8728af5e 100644
--- a/activerecord/test/models/notification.rb
+++ b/activerecord/test/models/notification.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Notification < ActiveRecord::Base
   validates_presence_of :message
 end
diff --git a/activerecord/test/models/numeric_data.rb b/activerecord/test/models/numeric_data.rb
new file mode 100644
index 0000000000..666e1a5778
--- /dev/null
+++ b/activerecord/test/models/numeric_data.rb
@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+class NumericData < ActiveRecord::Base
+  self.table_name = "numeric_data"
+  # Decimal columns with 0 scale being automatically treated as integers
+  # is deprecated, and will be removed in a future version of Rails.
+  attribute :world_population, :big_integer
+  attribute :my_house_population, :big_integer
+  attribute :atoms_in_universe, :big_integer
+end
diff --git a/activerecord/test/models/order.rb b/activerecord/test/models/order.rb
index 699be53959..36866b398f 100644
--- a/activerecord/test/models/order.rb
+++ b/activerecord/test/models/order.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Order < ActiveRecord::Base
   belongs_to :billing, class_name: "Customer", foreign_key: "billing_customer_id"
   belongs_to :shipping, class_name: "Customer", foreign_key: "shipping_customer_id"
diff --git a/activerecord/test/models/organization.rb b/activerecord/test/models/organization.rb
index 462830dadc..099e7e38e0 100644
--- a/activerecord/test/models/organization.rb
+++ b/activerecord/test/models/organization.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Organization < ActiveRecord::Base
   has_many :member_details
   has_many :members, through: :member_details
diff --git a/activerecord/test/models/other_dog.rb b/activerecord/test/models/other_dog.rb
index 418caf34be..a0fda5ae1b 100644
--- a/activerecord/test/models/other_dog.rb
+++ b/activerecord/test/models/other_dog.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency "models/arunit2_model"
 
 class OtherDog < ARUnit2Model
diff --git a/activerecord/test/models/owner.rb b/activerecord/test/models/owner.rb
index 21fc9b6eb8..5fa50d9918 100644
--- a/activerecord/test/models/owner.rb
+++ b/activerecord/test/models/owner.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Owner < ActiveRecord::Base
   self.primary_key = :owner_id
   has_many :pets, -> { order "pets.name desc" }
diff --git a/activerecord/test/models/parrot.rb b/activerecord/test/models/parrot.rb
index 1e5f9285a8..ba9ddb8c6a 100644
--- a/activerecord/test/models/parrot.rb
+++ b/activerecord/test/models/parrot.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Parrot < ActiveRecord::Base
   self.inheritance_column = :parrot_sti_class
 
@@ -8,7 +10,7 @@ class Parrot < ActiveRecord::Base
 
   validates_presence_of :name
 
-  attr_accessor :cancel_save_from_callback
+  attribute :cancel_save_from_callback
   before_save :cancel_save_callback_method, if: :cancel_save_from_callback
   def cancel_save_callback_method
     throw(:abort)
diff --git a/activerecord/test/models/person.rb b/activerecord/test/models/person.rb
index 18994d6f18..5cba1e440e 100644
--- a/activerecord/test/models/person.rb
+++ b/activerecord/test/models/person.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Person < ActiveRecord::Base
   has_many :readers
   has_many :secure_readers
diff --git a/activerecord/test/models/personal_legacy_thing.rb b/activerecord/test/models/personal_legacy_thing.rb
index adde7a504a..ed8b70cfcc 100644
--- a/activerecord/test/models/personal_legacy_thing.rb
+++ b/activerecord/test/models/personal_legacy_thing.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class PersonalLegacyThing < ActiveRecord::Base
   self.locking_column = :version
   belongs_to :person, counter_cache: true
diff --git a/activerecord/test/models/pet.rb b/activerecord/test/models/pet.rb
index 51a3e42815..9bda2109e6 100644
--- a/activerecord/test/models/pet.rb
+++ b/activerecord/test/models/pet.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Pet < ActiveRecord::Base
   attr_accessor :current_user
 
diff --git a/activerecord/test/models/pet_treasure.rb b/activerecord/test/models/pet_treasure.rb
index 1fe7807ffe..47b9f57fad 100644
--- a/activerecord/test/models/pet_treasure.rb
+++ b/activerecord/test/models/pet_treasure.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class PetTreasure < ActiveRecord::Base
   self.table_name = "pets_treasures"
 
diff --git a/activerecord/test/models/pirate.rb b/activerecord/test/models/pirate.rb
index c532ab426e..fd5083e597 100644
--- a/activerecord/test/models/pirate.rb
+++ b/activerecord/test/models/pirate.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Pirate < ActiveRecord::Base
   belongs_to :parrot, validate: true
   belongs_to :non_validated_parrot, class_name: "Parrot"
@@ -15,7 +17,13 @@ class Pirate < ActiveRecord::Base
     after_remove: proc { |p, pa| p.ship_log << "after_removing_proc_parrot_#{pa.id}" }
   has_and_belongs_to_many :autosaved_parrots, class_name: "Parrot", autosave: true
 
-  has_many :treasures, as: :looter
+  module PostTreasuresExtension
+    def build(attributes = {})
+      super({ name: "from extension" }.merge(attributes))
+    end
+  end
+
+  has_many :treasures, as: :looter, extend: PostTreasuresExtension
   has_many :treasure_estimates, through: :treasures, source: :price_estimates
 
   has_one :ship
diff --git a/activerecord/test/models/possession.rb b/activerecord/test/models/possession.rb
index 0226336c16..9b843e1525 100644
--- a/activerecord/test/models/possession.rb
+++ b/activerecord/test/models/possession.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Possession < ActiveRecord::Base
   self.table_name = "having"
 end
diff --git a/activerecord/test/models/post.rb b/activerecord/test/models/post.rb
index e74aedb814..528585fb75 100644
--- a/activerecord/test/models/post.rb
+++ b/activerecord/test/models/post.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Post < ActiveRecord::Base
   class CategoryPost < ActiveRecord::Base
     self.table_name = "categories_posts"
@@ -13,15 +15,16 @@ class Post < ActiveRecord::Base
 
   module NamedExtension2
     def greeting
-      "hello"
+      "hullo"
     end
   end
 
   scope :containing_the_letter_a, -> { where("body LIKE '%a%'") }
   scope :titled_with_an_apostrophe, -> { where("title LIKE '%''%'") }
-  scope :ranked_by_comments,      -> { order("comments_count DESC") }
+  scope :ranked_by_comments, -> { order(arel_attribute(:comments_count).desc) }
 
   scope :limit_by, lambda { |l| limit(l) }
+  scope :locked, -> { lock }
 
   belongs_to :author
   belongs_to :readonly_author, -> { readonly }, class_name: "Author", foreign_key: :author_id
@@ -59,6 +62,10 @@ class Post < ActiveRecord::Base
     def the_association
       proxy_association
     end
+
+    def with_content(content)
+      self.detect { |comment| comment.body == content }
+    end
   end
 
   has_many :comments_with_extend, extend: NamedExtension, class_name: "Comment", foreign_key: "post_id" do
@@ -99,6 +106,9 @@ class Post < ActiveRecord::Base
     end
   end
 
+  has_many :indestructible_taggings, as: :taggable, counter_cache: :indestructible_tags_count
+  has_many :indestructible_tags, through: :indestructible_taggings, source: :tag
+
   has_many :taggings_with_delete_all, class_name: "Tagging", as: :taggable, dependent: :delete_all, counter_cache: :taggings_with_delete_all_count
   has_many :taggings_with_destroy, class_name: "Tagging", as: :taggable, dependent: :destroy, counter_cache: :taggings_with_destroy_count
 
@@ -108,6 +118,7 @@ class Post < ActiveRecord::Base
   has_many :misc_tags, -> { where tags: { name: "Misc" } }, through: :taggings, source: :tag
   has_many :funky_tags, through: :taggings, source: :tag
   has_many :super_tags, through: :taggings
+  has_many :ordered_tags, through: :taggings
   has_many :tags_with_primary_key, through: :taggings, source: :tag_with_primary_key
   has_one :tagging, as: :taggable
 
@@ -177,14 +188,19 @@ end
 class SpecialPost < Post; end
 
 class StiPost < Post
-  self.abstract_class = true
   has_one :special_comment, class_name: "SpecialComment"
 end
 
+class AbstractStiPost < Post
+  self.abstract_class = true
+end
+
 class SubStiPost < StiPost
   self.table_name = Post.table_name
 end
 
+class SubAbstractStiPost < AbstractStiPost; end
+
 class FirstPost < ActiveRecord::Base
   self.inheritance_column = :disabled
   self.table_name = "posts"
@@ -194,6 +210,11 @@ class FirstPost < ActiveRecord::Base
   has_one  :comment,  foreign_key: :post_id
 end
 
+class TaggedPost < Post
+  has_many :taggings, -> { rewhere(taggable_type: "TaggedPost") }, as: :taggable
+  has_many :tags, through: :taggings
+end
+
 class PostWithDefaultInclude < ActiveRecord::Base
   self.inheritance_column = :disabled
   self.table_name = "posts"
@@ -232,6 +253,7 @@ class SpecialPostWithDefaultScope < ActiveRecord::Base
   self.inheritance_column = :disabled
   self.table_name = "posts"
   default_scope { where(id: [1, 5, 6]) }
+  scope :unscoped_all, -> { unscoped { all } }
 end
 
 class PostThatLoadsCommentsInAnAfterSaveHook < ActiveRecord::Base
@@ -271,3 +293,47 @@ end
 
 class SubConditionalStiPost < ConditionalStiPost
 end
+
+class FakeKlass
+  extend ActiveRecord::Delegation::DelegateCache
+
+  inherited self
+
+  class << self
+    def connection
+      Post.connection
+    end
+
+    def table_name
+      "posts"
+    end
+
+    def attribute_alias?(name)
+      false
+    end
+
+    def sanitize_sql(sql)
+      sql
+    end
+
+    def sanitize_sql_for_order(sql)
+      sql
+    end
+
+    def arel_attribute(name, table)
+      table[name]
+    end
+
+    def disallow_raw_sql!(*args)
+      # noop
+    end
+
+    def arel_table
+      Post.arel_table
+    end
+
+    def predicate_builder
+      Post.predicate_builder
+    end
+  end
+end
diff --git a/activerecord/test/models/price_estimate.rb b/activerecord/test/models/price_estimate.rb
index ce086e40a3..669d0991f7 100644
--- a/activerecord/test/models/price_estimate.rb
+++ b/activerecord/test/models/price_estimate.rb
@@ -1,4 +1,14 @@
+# frozen_string_literal: true
+
 class PriceEstimate < ActiveRecord::Base
+  include ActiveSupport::NumberHelper
+
   belongs_to :estimate_of, polymorphic: true
   belongs_to :thing, polymorphic: true
+
+  validates_numericality_of :price
+
+  def price
+    number_to_currency super
+  end
 end
diff --git a/activerecord/test/models/professor.rb b/activerecord/test/models/professor.rb
index 4dfb1a9602..abc23f40ff 100644
--- a/activerecord/test/models/professor.rb
+++ b/activerecord/test/models/professor.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency "models/arunit2_model"
 
 class Professor < ARUnit2Model
diff --git a/activerecord/test/models/project.rb b/activerecord/test/models/project.rb
index 4fbd986e40..846cef625b 100644
--- a/activerecord/test/models/project.rb
+++ b/activerecord/test/models/project.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Project < ActiveRecord::Base
   belongs_to :mentor
   has_and_belongs_to_many :developers, -> { distinct.order "developers.name desc, developers.id desc" }
diff --git a/activerecord/test/models/publisher.rb b/activerecord/test/models/publisher.rb
index 0d4a7f9235..53677197c4 100644
--- a/activerecord/test/models/publisher.rb
+++ b/activerecord/test/models/publisher.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 module Publisher
 end
diff --git a/activerecord/test/models/publisher/article.rb b/activerecord/test/models/publisher/article.rb
index d73a8eb936..355c22dcc5 100644
--- a/activerecord/test/models/publisher/article.rb
+++ b/activerecord/test/models/publisher/article.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Publisher::Article < ActiveRecord::Base
   has_and_belongs_to_many :magazines
   has_and_belongs_to_many :tags
diff --git a/activerecord/test/models/publisher/magazine.rb b/activerecord/test/models/publisher/magazine.rb
index 82e1a14008..425ede8df2 100644
--- a/activerecord/test/models/publisher/magazine.rb
+++ b/activerecord/test/models/publisher/magazine.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Publisher::Magazine < ActiveRecord::Base
   has_and_belongs_to_many :articles
 end
diff --git a/activerecord/test/models/randomly_named_c1.rb b/activerecord/test/models/randomly_named_c1.rb
index d4be1e13b4..f90a7b9336 100644
--- a/activerecord/test/models/randomly_named_c1.rb
+++ b/activerecord/test/models/randomly_named_c1.rb
@@ -1,3 +1,5 @@
-class ClassNameThatDoesNotFollowCONVENTIONS < ActiveRecord::Base

-  self.table_name = :randomly_named_table1

-end

+# frozen_string_literal: true
+
+class ClassNameThatDoesNotFollowCONVENTIONS < ActiveRecord::Base
+  self.table_name = :randomly_named_table1
+end
diff --git a/activerecord/test/models/rating.rb b/activerecord/test/models/rating.rb
index 7420821db0..cf06bc6931 100644
--- a/activerecord/test/models/rating.rb
+++ b/activerecord/test/models/rating.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Rating < ActiveRecord::Base
   belongs_to :comment
   has_many :taggings, as: :taggable
diff --git a/activerecord/test/models/reader.rb b/activerecord/test/models/reader.rb
index 7c5a159fe0..d25627e430 100644
--- a/activerecord/test/models/reader.rb
+++ b/activerecord/test/models/reader.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Reader < ActiveRecord::Base
   belongs_to :post
   belongs_to :person, inverse_of: :readers
diff --git a/activerecord/test/models/recipe.rb b/activerecord/test/models/recipe.rb
index c387230603..e53f5c8fb1 100644
--- a/activerecord/test/models/recipe.rb
+++ b/activerecord/test/models/recipe.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Recipe < ActiveRecord::Base
   belongs_to :chef
 end
diff --git a/activerecord/test/models/record.rb b/activerecord/test/models/record.rb
index f77ac9fc03..63143e296a 100644
--- a/activerecord/test/models/record.rb
+++ b/activerecord/test/models/record.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class Record < ActiveRecord::Base
 end
diff --git a/activerecord/test/models/reference.rb b/activerecord/test/models/reference.rb
index e2bb980fed..2a7a1e3b77 100644
--- a/activerecord/test/models/reference.rb
+++ b/activerecord/test/models/reference.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Reference < ActiveRecord::Base
   belongs_to :person
   belongs_to :job
diff --git a/activerecord/test/models/reply.rb b/activerecord/test/models/reply.rb
index a2d169292a..0ea110f4f8 100644
--- a/activerecord/test/models/reply.rb
+++ b/activerecord/test/models/reply.rb
@@ -1,9 +1,12 @@
+# frozen_string_literal: true
+
 require "models/topic"
 
 class Reply < Topic
   belongs_to :topic, foreign_key: "parent_id", counter_cache: true
-  belongs_to :topic_with_primary_key, class_name: "Topic", primary_key: "title", foreign_key: "parent_title", counter_cache: "replies_count"
+  belongs_to :topic_with_primary_key, class_name: "Topic", primary_key: "title", foreign_key: "parent_title", counter_cache: "replies_count", touch: true
   has_many :replies, class_name: "SillyReply", dependent: :destroy, foreign_key: "parent_id"
+  has_many :silly_unique_replies, dependent: :destroy, foreign_key: "parent_id"
 end
 
 class UniqueReply < Reply
@@ -12,6 +15,7 @@ class UniqueReply < Reply
 end
 
 class SillyUniqueReply < UniqueReply
+  validates :content, uniqueness: true
 end
 
 class WrongReply < Reply
diff --git a/activerecord/test/models/ship.rb b/activerecord/test/models/ship.rb
index 77a7b22315..7973219a79 100644
--- a/activerecord/test/models/ship.rb
+++ b/activerecord/test/models/ship.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Ship < ActiveRecord::Base
   self.record_timestamps = false
 
diff --git a/activerecord/test/models/ship_part.rb b/activerecord/test/models/ship_part.rb
index 1a633b8d77..f6d7a8ae5e 100644
--- a/activerecord/test/models/ship_part.rb
+++ b/activerecord/test/models/ship_part.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ShipPart < ActiveRecord::Base
   belongs_to :ship
   has_many :trinkets, class_name: "Treasure", as: :looter
diff --git a/activerecord/test/models/shop.rb b/activerecord/test/models/shop.rb
index f9d23d13b0..92afe70b92 100644
--- a/activerecord/test/models/shop.rb
+++ b/activerecord/test/models/shop.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Shop
   class Collection < ActiveRecord::Base
     has_many :products, dependent: :nullify
diff --git a/activerecord/test/models/shop_account.rb b/activerecord/test/models/shop_account.rb
index 1580e8b20c..97fb058331 100644
--- a/activerecord/test/models/shop_account.rb
+++ b/activerecord/test/models/shop_account.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ShopAccount < ActiveRecord::Base
   belongs_to :customer
   belongs_to :customer_carrier
diff --git a/activerecord/test/models/speedometer.rb b/activerecord/test/models/speedometer.rb
index 497c3aba9a..e456907a22 100644
--- a/activerecord/test/models/speedometer.rb
+++ b/activerecord/test/models/speedometer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Speedometer < ActiveRecord::Base
   self.primary_key = :speedometer_id
   belongs_to :dashboard
diff --git a/activerecord/test/models/sponsor.rb b/activerecord/test/models/sponsor.rb
index 3f142b25fe..18ff103ffe 100644
--- a/activerecord/test/models/sponsor.rb
+++ b/activerecord/test/models/sponsor.rb
@@ -1,6 +1,9 @@
+# frozen_string_literal: true
+
 class Sponsor < ActiveRecord::Base
   belongs_to :sponsor_club, class_name: "Club", foreign_key: "club_id"
   belongs_to :sponsorable, polymorphic: true
+  belongs_to :sponsor, polymorphic: true
   belongs_to :thing, polymorphic: true, foreign_type: :sponsorable_type, foreign_key: :sponsorable_id
   belongs_to :sponsorable_with_conditions, -> { where name: "Ernie" }, polymorphic: true,
              foreign_type: "sponsorable_type", foreign_key: "sponsorable_id"
diff --git a/activerecord/test/models/string_key_object.rb b/activerecord/test/models/string_key_object.rb
index f084ec1bdc..473c145f4c 100644
--- a/activerecord/test/models/string_key_object.rb
+++ b/activerecord/test/models/string_key_object.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class StringKeyObject < ActiveRecord::Base
   self.primary_key = :id
 end
diff --git a/activerecord/test/models/student.rb b/activerecord/test/models/student.rb
index 28a0b6c99b..e750798f74 100644
--- a/activerecord/test/models/student.rb
+++ b/activerecord/test/models/student.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Student < ActiveRecord::Base
   has_and_belongs_to_many :lessons
   belongs_to :college
diff --git a/activerecord/test/models/subject.rb b/activerecord/test/models/subject.rb
deleted file mode 100644
index 504f68a296..0000000000
--- a/activerecord/test/models/subject.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-# used for OracleSynonymTest, see test/synonym_test_oracle.rb
-#
-class Subject < ActiveRecord::Base
-  # added initialization of author_email_address in the same way as in Topic class
-  # as otherwise synonym test was failing
-  after_initialize :set_email_address
-
-  private
-    def set_email_address
-      unless persisted?
-        self.author_email_address = "test@test.com"
-      end
-    end
-end
diff --git a/activerecord/test/models/subscriber.rb b/activerecord/test/models/subscriber.rb
index a820329003..b21969ca2d 100644
--- a/activerecord/test/models/subscriber.rb
+++ b/activerecord/test/models/subscriber.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Subscriber < ActiveRecord::Base
   self.primary_key = "nick"
   has_many :subscriptions
diff --git a/activerecord/test/models/subscription.rb b/activerecord/test/models/subscription.rb
index 1cedf6deae..d1d5d21621 100644
--- a/activerecord/test/models/subscription.rb
+++ b/activerecord/test/models/subscription.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Subscription < ActiveRecord::Base
   belongs_to :subscriber, counter_cache: :books_count
   belongs_to :book
diff --git a/activerecord/test/models/tag.rb b/activerecord/test/models/tag.rb
index c907aea10f..c1a8890a8a 100644
--- a/activerecord/test/models/tag.rb
+++ b/activerecord/test/models/tag.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Tag < ActiveRecord::Base
   has_many :taggings
   has_many :taggables, through: :taggings
@@ -9,5 +11,6 @@ end
 class OrderedTag < Tag
   self.table_name = "tags"
 
-  has_many :taggings, -> { order("taggings.id DESC") }, foreign_key: "tag_id"
+  has_many :ordered_taggings, -> { order("taggings.id DESC") }, foreign_key: "tag_id", class_name: "Tagging"
+  has_many :tagged_posts, through: :ordered_taggings, source: "taggable", source_type: "Post"
 end
diff --git a/activerecord/test/models/tagging.rb b/activerecord/test/models/tagging.rb
index f739b4a197..6d4230f6f4 100644
--- a/activerecord/test/models/tagging.rb
+++ b/activerecord/test/models/tagging.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # test that attr_readonly isn't called on the :taggable polymorphic association
 module Taggable
 end
@@ -6,8 +8,13 @@ class Tagging < ActiveRecord::Base
   belongs_to :tag, -> { includes(:tagging) }
   belongs_to :super_tag,   class_name: "Tag", foreign_key: "super_tag_id"
   belongs_to :invalid_tag, class_name: "Tag", foreign_key: "tag_id"
+  belongs_to :ordered_tag, class_name: "OrderedTag", foreign_key: "tag_id"
   belongs_to :blue_tag, -> { where tags: { name: "Blue" } }, class_name: "Tag", foreign_key: :tag_id
   belongs_to :tag_with_primary_key, class_name: "Tag", foreign_key: :tag_id, primary_key: :custom_primary_key
   belongs_to :taggable, polymorphic: true, counter_cache: :tags_count
   has_many :things, through: :taggable
 end
+
+class IndestructibleTagging < Tagging
+  before_destroy { throw :abort }
+end
diff --git a/activerecord/test/models/task.rb b/activerecord/test/models/task.rb
index e36989dd56..dabe3ce06b 100644
--- a/activerecord/test/models/task.rb
+++ b/activerecord/test/models/task.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Task < ActiveRecord::Base
   def updated_at
     ending
diff --git a/activerecord/test/models/topic.rb b/activerecord/test/models/topic.rb
index 0420e2d15c..72699046f9 100644
--- a/activerecord/test/models/topic.rb
+++ b/activerecord/test/models/topic.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Topic < ActiveRecord::Base
   scope :base, -> { all }
   scope :written_before, lambda { |time|
@@ -10,11 +12,19 @@ class Topic < ActiveRecord::Base
 
   scope :scope_with_lambda, lambda { all }
 
+  scope :by_private_lifo, -> { where(author_name: private_lifo) }
   scope :by_lifo, -> { where(author_name: "lifo") }
   scope :replied, -> { where "replies_count > 0" }
 
+  class << self
+    private
+      def private_lifo
+        "lifo"
+      end
+  end
+
   scope "approved_as_string", -> { where(approved: true) }
-  scope :anonymous_extension, -> { all } do
+  scope :anonymous_extension, -> {} do
     def one
       1
     end
@@ -63,11 +73,24 @@ class Topic < ActiveRecord::Base
 
   after_initialize :set_email_address
 
+  attr_accessor :change_approved_before_save
+  before_save :change_approved_callback
+
   class_attribute :after_initialize_called
   after_initialize do
     self.class.after_initialize_called = true
   end
 
+  attr_accessor :after_touch_called
+
+  after_initialize do
+    self.after_touch_called = 0
+  end
+
+  after_touch do
+    self.after_touch_called += 1
+  end
+
   def approved=(val)
     @custom_approved = val
     write_attribute(:approved, val)
@@ -84,7 +107,7 @@ class Topic < ActiveRecord::Base
     end
 
     def set_email_address
-      unless persisted?
+      unless persisted? || will_save_change_to_author_email_address?
         self.author_email_address = "test@test.com"
       end
     end
@@ -94,6 +117,10 @@ class Topic < ActiveRecord::Base
     def before_destroy_for_transaction; end
     def after_save_for_transaction; end
     def after_create_for_transaction; end
+
+    def change_approved_callback
+      self.approved = change_approved_before_save unless change_approved_before_save.nil?
+    end
 end
 
 class ImportantTopic < Topic
diff --git a/activerecord/test/models/toy.rb b/activerecord/test/models/toy.rb
index ddc7048a56..4a5697eeb1 100644
--- a/activerecord/test/models/toy.rb
+++ b/activerecord/test/models/toy.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Toy < ActiveRecord::Base
   self.primary_key = :toy_id
   belongs_to :pet
diff --git a/activerecord/test/models/traffic_light.rb b/activerecord/test/models/traffic_light.rb
index a6b7edb882..0b88815cbd 100644
--- a/activerecord/test/models/traffic_light.rb
+++ b/activerecord/test/models/traffic_light.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class TrafficLight < ActiveRecord::Base
   serialize :state, Array
   serialize :long_state, Array
diff --git a/activerecord/test/models/treasure.rb b/activerecord/test/models/treasure.rb
index fb2a5d44e2..b51db56c37 100644
--- a/activerecord/test/models/treasure.rb
+++ b/activerecord/test/models/treasure.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Treasure < ActiveRecord::Base
   has_and_belongs_to_many :parrots
   belongs_to :looter, polymorphic: true
diff --git a/activerecord/test/models/treaty.rb b/activerecord/test/models/treaty.rb
index 373cd48f71..5c1d75aa09 100644
--- a/activerecord/test/models/treaty.rb
+++ b/activerecord/test/models/treaty.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Treaty < ActiveRecord::Base
   self.primary_key = :treaty_id
 
diff --git a/activerecord/test/models/tree.rb b/activerecord/test/models/tree.rb
index dc29cccc9c..77050c5fff 100644
--- a/activerecord/test/models/tree.rb
+++ b/activerecord/test/models/tree.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Tree < ActiveRecord::Base
   has_many :nodes, dependent: :destroy
 end
diff --git a/activerecord/test/models/tuning_peg.rb b/activerecord/test/models/tuning_peg.rb
index 1252d6dc1d..6e052e1d0f 100644
--- a/activerecord/test/models/tuning_peg.rb
+++ b/activerecord/test/models/tuning_peg.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class TuningPeg < ActiveRecord::Base
   belongs_to :guitar
   validates_numericality_of :pitch
diff --git a/activerecord/test/models/tyre.rb b/activerecord/test/models/tyre.rb
index e50a21ca68..d627026585 100644
--- a/activerecord/test/models/tyre.rb
+++ b/activerecord/test/models/tyre.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Tyre < ActiveRecord::Base
   belongs_to :car
 
diff --git a/activerecord/test/models/user.rb b/activerecord/test/models/user.rb
index 5089a795f4..3efbc45d2a 100644
--- a/activerecord/test/models/user.rb
+++ b/activerecord/test/models/user.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "models/job"
 
 class User < ActiveRecord::Base
diff --git a/activerecord/test/models/uuid_child.rb b/activerecord/test/models/uuid_child.rb
index a3d0962ad6..9fce361cc8 100644
--- a/activerecord/test/models/uuid_child.rb
+++ b/activerecord/test/models/uuid_child.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class UuidChild < ActiveRecord::Base
   belongs_to :uuid_parent
 end
diff --git a/activerecord/test/models/uuid_item.rb b/activerecord/test/models/uuid_item.rb
index 2353e40213..41f68c4c18 100644
--- a/activerecord/test/models/uuid_item.rb
+++ b/activerecord/test/models/uuid_item.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class UuidItem < ActiveRecord::Base
 end
 
diff --git a/activerecord/test/models/uuid_parent.rb b/activerecord/test/models/uuid_parent.rb
index 5634f22d0c..05db61855e 100644
--- a/activerecord/test/models/uuid_parent.rb
+++ b/activerecord/test/models/uuid_parent.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class UuidParent < ActiveRecord::Base
   has_many :uuid_children
 end
diff --git a/activerecord/test/models/vegetables.rb b/activerecord/test/models/vegetables.rb
index a4590d06e0..cfaab08ed1 100644
--- a/activerecord/test/models/vegetables.rb
+++ b/activerecord/test/models/vegetables.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Vegetable < ActiveRecord::Base
   validates_presence_of :name
 
diff --git a/activerecord/test/models/vehicle.rb b/activerecord/test/models/vehicle.rb
index 855bc4e325..c9b3338522 100644
--- a/activerecord/test/models/vehicle.rb
+++ b/activerecord/test/models/vehicle.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Vehicle < ActiveRecord::Base
   self.abstract_class = true
   default_scope -> { where("tires_count IS NOT NULL") }
diff --git a/activerecord/test/models/vertex.rb b/activerecord/test/models/vertex.rb
index 3d19433b6f..0ad8114898 100644
--- a/activerecord/test/models/vertex.rb
+++ b/activerecord/test/models/vertex.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This class models a vertex in a directed graph.
 class Vertex < ActiveRecord::Base
   has_many :sink_edges, class_name: "Edge", foreign_key: "source_id"
diff --git a/activerecord/test/models/warehouse_thing.rb b/activerecord/test/models/warehouse_thing.rb
index f20bd1a245..099633af55 100644
--- a/activerecord/test/models/warehouse_thing.rb
+++ b/activerecord/test/models/warehouse_thing.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class WarehouseThing < ActiveRecord::Base
   self.table_name = "warehouse-things"
 
diff --git a/activerecord/test/models/wheel.rb b/activerecord/test/models/wheel.rb
index cba2b3e518..22fc74995f 100644
--- a/activerecord/test/models/wheel.rb
+++ b/activerecord/test/models/wheel.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Wheel < ActiveRecord::Base
-  belongs_to :wheelable, polymorphic: true, counter_cache: true
+  belongs_to :wheelable, polymorphic: true, counter_cache: true, touch: :wheels_owned_at
 end
diff --git a/activerecord/test/models/without_table.rb b/activerecord/test/models/without_table.rb
index 7c0fc286e1..fc0a52d6ad 100644
--- a/activerecord/test/models/without_table.rb
+++ b/activerecord/test/models/without_table.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class WithoutTable < ActiveRecord::Base
   default_scope -> { where(published: true) }
 end
diff --git a/activerecord/test/models/zine.rb b/activerecord/test/models/zine.rb
index 3f2b348b46..6f361665ef 100644
--- a/activerecord/test/models/zine.rb
+++ b/activerecord/test/models/zine.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Zine < ActiveRecord::Base
   has_many :interests, inverse_of: :zine
 end