Correct XML ampersand fixup

test/test_utils.py

@@ -16,6 +16,7 @@ from youtube_dl.utils import (
     DateRange,
     encodeFilename,
     find_xpath_attr,
+    fix_xml_ampersands,
     get_meta_content,
     orderedSet,
     parse_duration,
@@ -200,5 +201,18 @@ class TestUtil(unittest.TestCase):
         self.assertEqual(parse_duration('9:12:43'), 33163)
         self.assertEqual(parse_duration('x:y'), None)
 
+    def test_fix_xml_ampersands(self):
+        self.assertEqual(
+            fix_xml_ampersands('"&x=y&z=a'), '"&x=y&z=a')
+        self.assertEqual(
+            fix_xml_ampersands('"&x=y&wrong;&z=a'),
+            '"&x=y&wrong;&z=a')
+        self.assertEqual(
+            fix_xml_ampersands('&'><"'),
+            '&'><"')
+        self.assertEqual(
+            fix_xml_ampersands('Ӓ᪼'), 'Ӓ᪼')
+        self.assertEqual(fix_xml_ampersands('&#&#'), '&#&#')
+
 if __name__ == '__main__':
     unittest.main()