AR specific length validator to respect `marked_for_destruction`.

Closes #7247.

Conflicts:
	activerecord/CHANGELOG.md
	activerecord/test/models/owner.rb

2 files changed, 20 insertions, 0 deletions

diff --git a/activerecord/test/cases/validations/length_validation_test.rb b/activerecord/test/cases/validations/length_validation_test.rb
index 4a92da38ce..2c0e282761 100644
--- a/activerecord/test/cases/validations/length_validation_test.rb
+++ b/activerecord/test/cases/validations/length_validation_test.rb
@@ -2,6 +2,7 @@
 require "cases/helper"
 require 'models/owner'
 require 'models/pet'
+require 'models/person'
 
 class LengthValidationTest < ActiveRecord::TestCase
   fixtures :owners
@@ -44,4 +45,21 @@ class LengthValidationTest < ActiveRecord::TestCase
       assert o.valid?
     end
   end
+
+  def test_validates_size_of_reprects_records_marked_for_destruction
+    assert_nothing_raised { Owner.validates_size_of :pets, minimum: 1 }
+    owner = Owner.new
+    assert_not owner.save
+    assert owner.errors[:pets].any?
+    pet = owner.pets.build
+    assert owner.valid?
+    assert owner.save
+
+    pet_count = Pet.count
+    assert_not owner.update_attributes pets_attributes: [ {_destroy: 1, id: pet.id} ]
+    assert_not owner.valid?
+    assert owner.errors[:pets].any?
+    assert_equal pet_count, Pet.count
+  end
+
 end
diff --git a/activerecord/test/models/owner.rb b/activerecord/test/models/owner.rb
index 2e3a9a3681..cedb774b10 100644
--- a/activerecord/test/models/owner.rb
+++ b/activerecord/test/models/owner.rb
@@ -17,6 +17,8 @@ class Owner < ActiveRecord::Base
 
   after_commit :execute_blocks
 
+  accepts_nested_attributes_for :pets, allow_destroy: true
+
   def blocks
     @blocks ||= []
   end