gh-142754: Ensure that Element & Attr instances have the ownerDocument attribute

Lib/test/test_minidom.py

@@ -9,7 +9,7 @@
 
 importxml.dom.minidom
 
-fromxml.dom.minidomimportparse, Attr, Node, Document, parseString
+fromxml.dom.minidomimportparse, Attr, Node, Document, Element, parseString
 fromxml.dom.minidomimportgetDOMImplementation
 fromxml.parsers.expatimportExpatError
 
@@ -191,6 +191,14 @@ def testAppendChildNoQuadraticComplexity(self):
 # This example used to take at least 30 seconds.
 self.assertLess(end-start, 1)
 
+deftestSetAttributeNodeWithoutOwnerDocument(self):
+# regression test for gh-142754
+elem=Element("test")
+attr=Attr("id")
+attr.value="test-id"
+elem.setAttributeNode(attr)
+self.assertEqual(elem.getAttribute("id"), "test-id")
+
 deftestAppendChildFragment(self):
 dom, orig, c1, c2, c3, frag=self._create_fragment_test_nodes()
 dom.documentElement.appendChild(frag)

Lib/xml/dom/minidom.py

@@ -364,6 +364,7 @@ class Attr(Node):
  def __init__(self, qName, namespaceURI=EMPTY_NAMESPACE, localName=None,
  prefix=None):
  self.ownerElement = None
+ self.ownerDocument = None
  self._name = qName
  self.namespaceURI = namespaceURI
  self._prefix = prefix
@@ -689,6 +690,7 @@ class Element(Node):
 
  def __init__(self, tagName, namespaceURI=EMPTY_NAMESPACE, prefix=None,
  localName=None):
+ self.ownerDocument = None
  self.parentNode = None
  self.tagName = self.nodeName = tagName
  self.prefix = prefix

Misc/NEWS.d/next/Library/2025-12-16-11-55-55.gh-issue-142754.xuCrt3.rst

@@ -0,0 +1,4 @@
+Add the *ownerDocument* attribute to :mod:`xml.dom.minidom` elements and attributes
+created by directly instantiating the ``Element`` or ``Attr`` class. Note that
+this way of creating nodes is not supported; creator functions like
+:py:meth:`xml.dom.Document.documentElement` should be used instead.