From 6302a8f17a6113a3ef0cbb3afad35632a7be9e02 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Thu, 14 May 2026 12:37:11 +0200
Subject: [PATCH] [3.15] gh-148821: Add more tests for invalid XML encodings
 (GH-149820) (GH-149821)

(cherry picked from commit c6f7368157ecf9f2cdd537d8b6fad6e011bce344)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
---
 Lib/test/test_pyexpat.py | 48 ++++++++++++++++++++++++++++++++++++----
 1 file changed, 44 insertions(+), 4 deletions(-)

diff --git a/Lib/test/test_pyexpat.py b/Lib/test/test_pyexpat.py
index 4fe2e02326f0..10dca684acce 100644
--- a/Lib/test/test_pyexpat.py
+++ b/Lib/test/test_pyexpat.py
@@ -289,7 +289,7 @@ class ParseTest(unittest.TestCase):
         'mac-roman', 'mac-turkish',
         'koi8-r', 'koi8-t', 'koi8-u', 'kz1048', 'ptcp154',
     ])
-    def test_supported_ecodings(self, encoding):
+    def test_supported_encodings(self, encoding):
         out = self.Outputter()
         parser = expat.ParserCreate()
         self._hookup_callbacks(parser, out)
@@ -308,7 +308,7 @@ class ParseTest(unittest.TestCase):
         'UTF-8', 'utf-8', 'utf-16', 'utf-16le', 'utf-16be',
         'koi8-u', 'cp1125', 'cp1251', 'iso8859-5', 'mac-cyrillic',
     ])
-    def test_supported_ecodings2(self, encoding):
+    def test_supported_encodings2(self, encoding):
         out = self.Outputter()
         parser = expat.ParserCreate()
         self._hookup_callbacks(parser, out)
@@ -334,14 +334,54 @@ class ParseTest(unittest.TestCase):
         "johab",
         "Shift_JIS", "Shift_JIS-2004", "Shift_JISX0213",
     ])
-    def test_unsupportes_ecodings(self, encoding):
+    def test_unsupported_encodings(self, encoding):
         parser = expat.ParserCreate()
         data = (f'<?xml version="1.0" encoding="{encoding}"?>\n'
                 '<root></root>').encode(encoding)
         with self.assertRaises(ValueError):
             parser.Parse(data, True)
 
-    def test_unknown_ecoding(self):
+        parser = expat.ParserCreate()
+        data = (f'<?xml version="1.0" encoding="{encoding}"?>\n'
+                '<root></root>').encode()
+        with self.assertRaises(ValueError):
+            parser.Parse(data, True)
+
+    @support.subTests('encoding', [
+        'cp037', 'cp273', 'cp424', 'cp500', 'cp864', 'cp875',
+        'cp1026', 'cp1140',
+        'mac_arabic', 'mac_farsi',
+    ])
+    def test_incompatible_encodings(self, encoding):
+        parser = expat.ParserCreate()
+        data = (f'<?xml version="1.0" encoding="{encoding}"?>\n'
+                '<root></root>').encode(encoding)
+        with self.assertRaises(expat.ExpatError):
+            parser.Parse(data, True)
+
+        parser = expat.ParserCreate()
+        data = (f'<?xml version="1.0" encoding="{encoding}"?>\n'
+                '<root></root>').encode()
+        with self.assertRaisesRegex(expat.ExpatError, 'unknown encoding'):
+            parser.Parse(data, True)
+
+    @support.subTests('encoding', [
+        'hex_codec', 'rot_13',
+    ])
+    def test_non_text_encodings(self, encoding):
+        parser = expat.ParserCreate()
+        data = (f'<?xml version="1.0" encoding="{encoding}"?>\n'
+                '<root></root>').encode()
+        with self.assertRaises(LookupError):
+            parser.Parse(data, True)
+
+    def test_undefined_encoding(self):
+        parser = expat.ParserCreate()
+        data = b'<?xml version="1.0" encoding="undefined"?>\n<root></root>'
+        with self.assertRaises(UnicodeError):
+            parser.Parse(data, True)
+
+    def test_unknown_encoding(self):
         parser = expat.ParserCreate()
         data = b'<?xml version="1.0" encoding="xyz"?>\n<root></root>'
         with self.assertRaises(LookupError):
-- 
2.47.3