bpo-31758: Prevent crashes when using an uninitialized _elementtree.XMLParser object (GH-3997)

1 files changed, 15 insertions, 0 deletions

diff --git a/Lib/test/test_xml_etree_c.py b/Lib/test/test_xml_etree_c.py
index 15496fd..7437e13 100644
--- a/Lib/test/test_xml_etree_c.py
+++ b/Lib/test/test_xml_etree_c.py
@@ -115,6 +115,21 @@ class MiscTests(unittest.TestCase):
         elem.tail = X()
         elem.__setstate__({'tag': 42})  # shouldn't cause an assertion failure
 
+    @support.cpython_only
+    def test_uninitialized_parser(self):
+        # The interpreter shouldn't crash in case of calling methods or
+        # accessing attributes of uninitialized XMLParser objects.
+        parser = cET.XMLParser.__new__(cET.XMLParser)
+        self.assertRaises(ValueError, parser.close)
+        self.assertRaises(ValueError, parser.feed, 'foo')
+        class MockFile:
+            def read(*args):
+                return ''
+        self.assertRaises(ValueError, parser._parse_whole, MockFile())
+        self.assertRaises(ValueError, parser._setevents, None)
+        self.assertIsNone(parser.entity)
+        self.assertIsNone(parser.target)
+
     def test_setstate_leaks(self):
         # Test reference leaks
         elem = cET.Element.__new__(cET.Element)