Merge pull request rails#53669 from a5-stable/copy-previously_new_record-at-becomes

Ensure previously_new_record? is preserved in #becomes

Author: kamipo

activerecord/lib/active_record/persistence.rb

@@ -492,6 +492,7 @@ def becomes(klass)
         becoming.instance_variable_set(:@attributes, @attributes)
         becoming.instance_variable_set(:@mutations_from_database, @mutations_from_database ||= nil)
         becoming.instance_variable_set(:@new_record, new_record?)
+        becoming.instance_variable_set(:@previously_new_record, previously_new_record?)
         becoming.instance_variable_set(:@destroyed, destroyed?)
         becoming.errors.copy!(errors)
       end

activerecord/test/cases/persistence_test.rb

@@ -460,6 +460,17 @@ def test_becomes_includes_changed_attributes
     assert_equal %w{name}, client.changed
   end
 
+  def test_becomes_preserve_record_status
+    company = Company.new(name: "37signals")
+    client = company.becomes(Client)
+    assert_predicate client, :new_record?
+
+    company.save
+    client = company.becomes(Client)
+    assert_predicate client, :persisted?
+    assert_predicate client, :previously_new_record?
+  end
+
   def test_becomes_initializes_missing_attributes
     company = Company.new(name: "GrowingCompany")