clean the erros if an object that includes validations errors is duped. Fixes #5953

1 files changed, 15 insertions, 0 deletions

diff --git a/activemodel/test/cases/validations_test.rb b/activemodel/test/cases/validations_test.rb
index a716d0896e..f9bb877316 100644
--- a/activemodel/test/cases/validations_test.rb
+++ b/activemodel/test/cases/validations_test.rb
@@ -344,4 +344,19 @@ class ValidationsTest < ActiveModel::TestCase
     Topic.validates :title, options
     assert_equal({ :presence => true }, options)
   end
+  
+  def test_dup_validity_is_independent
+    Topic.validates_presence_of :title
+    topic = Topic.new("title" => "Litterature")
+    topic.valid?
+
+    duped = topic.dup
+    duped.title = nil
+    assert duped.invalid?
+
+    topic.title = nil
+    duped.title = 'Mathematics'
+    assert topic.invalid?
+    assert duped.valid?
+  end
 end