Dynamically modified schema and association would not be correctly reset

This fixes <"SQLite3::SQLException: no such column: legacy_things.person_id: SELECT \"legacy_things\".* FROM \"legacy_things\" WHERE \"legacy_things\".\"person_id\" = ?">
in OptimisticLockingTest#test_lock_destroy

activerecord/test/cases/locking_test.rb

@@ -5,6 +5,7 @@
 require 'models/reader'
 require 'models/ship'
 require 'models/legacy_thing'
+require 'models/personal_legacy_thing'
 require 'models/reference'
 require 'models/string_key_object'
 require 'models/car'
@@ -311,32 +312,24 @@ class OptimisticLockingWithSchemaChangeTest < ActiveRecord::TestCase
 
   # See Lighthouse ticket #1966
   def test_destroy_dependents
-    # Establish dependent relationship between People and LegacyThing
-    add_counter_column_to(Person, 'legacy_things_count')
-    LegacyThing.connection.add_column LegacyThing.table_name, 'person_id', :integer
-    LegacyThing.reset_column_information
-    LegacyThing.class_eval do
-      belongs_to :person, :counter_cache => true
-    end
-    Person.class_eval do
-      has_many :legacy_things, :dependent => :destroy
-    end
+    # Establish dependent relationship between Person and PersonalLegacyThing
+    add_counter_column_to(Person, 'personal_legacy_things_count')
+    PersonalLegacyThing.reset_column_information
 
     # Make sure that counter incrementing doesn't cause problems
     p1 = Person.new(:first_name => 'fjord')
     p1.save!
-    t = LegacyThing.new(:person => p1)
+    t = PersonalLegacyThing.new(:person => p1)
     t.save!
     p1.reload
-    assert_equal 1, p1.legacy_things_count
+    assert_equal 1, p1.personal_legacy_things_count
     assert p1.destroy
     assert_equal true, p1.frozen?
     assert_raises(ActiveRecord::RecordNotFound) { Person.find(p1.id) }
-    assert_raises(ActiveRecord::RecordNotFound) { LegacyThing.find(t.id) }
+    assert_raises(ActiveRecord::RecordNotFound) { PersonalLegacyThing.find(t.id) }
   ensure
-    remove_counter_column_from(Person, 'legacy_things_count')
-    LegacyThing.connection.remove_column LegacyThing.table_name, 'person_id'
-    LegacyThing.reset_column_information
+    remove_counter_column_from(Person, 'personal_legacy_things_count')
+    PersonalLegacyThing.reset_column_information
   end
 
   private

activerecord/test/models/person.rb

@@ -30,6 +30,8 @@ class Person < ActiveRecord::Base
   has_many :agents_of_agents, :through => :agents, :source => :agents
   belongs_to :number1_fan, :class_name => 'Person'
 
+  has_many :personal_legacy_things, :dependent => :destroy
+
   has_many :agents_posts,         :through => :agents,       :source => :posts
   has_many :agents_posts_authors, :through => :agents_posts, :source => :author
   has_many :essays, primary_key: "first_name", foreign_key: "writer_id"

activerecord/test/models/personal_legacy_thing.rb

@@ -0,0 +1,4 @@
+class PersonalLegacyThing < ActiveRecord::Base
+  self.locking_column = :version
+  belongs_to :person, :counter_cache => true
+end

activerecord/test/schema/schema.rb

@@ -546,6 +546,12 @@ def except(adapter_names_to_exclude)
     t.column :treasure_id, :integer
   end
 
+  create_table :personal_legacy_things, force: true do |t|
+    t.integer :tps_report_number
+    t.integer :person_id
+    t.integer :version, null: false, default: 0
+  end
+
   create_table :pets, primary_key: :pet_id, force: true do |t|
     t.string :name
     t.integer :owner_id, :integer