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.diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 1fe1cba..ad22dfe 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -3886,16 +3886,6 @@
self.assertEqual(f.mode, "wb")
f.close()
- with support.check_warnings(('', DeprecationWarning)):
- f = self.open(support.TESTFN, "U")
- self.assertEqual(f.name, support.TESTFN)
- self.assertEqual(f.buffer.name, support.TESTFN)
- self.assertEqual(f.buffer.raw.name, support.TESTFN)
- self.assertEqual(f.mode, "U")
- self.assertEqual(f.buffer.mode, "rb")
- self.assertEqual(f.buffer.raw.mode, "rb")
- f.close()
-
f = self.open(support.TESTFN, "w+")
self.assertEqual(f.mode, "w+")
self.assertEqual(f.buffer.mode, "rb+") # Does it really matter?
@@ -3909,6 +3899,13 @@
f.close()
g.close()
+ def test_removed_u_mode(self):
+ # "U" mode has been removed in Python 3.9
+ for mode in ("U", "rU", "r+U"):
+ with self.assertRaises(ValueError) as cm:
+ self.open(support.TESTFN, mode)
+ self.assertIn('invalid mode', str(cm.exception))
+
def test_io_after_close(self):
for kwargs in [
{"mode": "w"},