bpo-37330: open() no longer accept 'U' in file mode (GH-16959)

open(), io.open(), codecs.open() and fileinput.FileInput no longer
accept "U" ("universal newline") in the file mode. This flag was
deprecated since Python 3.3.

1 files changed, 15 insertions, 3 deletions

diff --git a/Lib/test/test_codecs.py b/Lib/test/test_codecs.py
index b37525bf660..e1638c11168 100644
--- a/Lib/test/test_codecs.py
+++ b/Lib/test/test_codecs.py
@@ -712,11 +712,23 @@ class UTF16Test(ReadTest, unittest.TestCase):
         self.addCleanup(support.unlink, support.TESTFN)
         with open(support.TESTFN, 'wb') as fp:
             fp.write(s)
-        with support.check_warnings(('', DeprecationWarning)):
-            reader = codecs.open(support.TESTFN, 'U', encoding=self.encoding)
-        with reader:
+        with codecs.open(support.TESTFN, 'r',
+                         encoding=self.encoding) as reader:
             self.assertEqual(reader.read(), s1)
 
+    def test_invalid_modes(self):
+        for mode in ('U', 'rU', 'r+U'):
+            with self.assertRaises(ValueError) as cm:
+                codecs.open(support.TESTFN, mode, encoding=self.encoding)
+            self.assertIn('invalid mode', str(cm.exception))
+
+        for mode in ('rt', 'wt', 'at', 'r+t'):
+            with self.assertRaises(ValueError) as cm:
+                codecs.open(support.TESTFN, mode, encoding=self.encoding)
+            self.assertIn("can't have text and binary mode at once",
+                          str(cm.exception))
+
+
 class UTF16LETest(ReadTest, unittest.TestCase):
     encoding = "utf-16-le"
     ill_formed_sequence = b"\x80\xdc"