1 files changed, 11 insertions, 0 deletions
diff --git a/Lib/test/test_fileio.py b/Lib/test/test_fileio.py
index a676bc2..0404a19 100644
--- a/Lib/test/test_fileio.py
+++ b/Lib/test/test_fileio.py
@@ -100,6 +100,17 @@ class AutoFileTests(unittest.TestCase):
             # should raise on closed file
             self.assertRaises(ValueError, method)
 
+    def testOpendir(self):
+        # Issue 3703: opening a directory should fill the errno
+        # Windows always returns "[Errno 13]: Permission denied
+        # Unix calls dircheck() and returns "[Errno 21]: Is a directory"
+        try:
+            _fileio._FileIO('.', 'r')
+        except IOError as e:
+            self.assertNotEqual(e.errno, 0)
+        else:
+            self.fail("Should have raised IOError")
+
 
 class OtherFileTests(unittest.TestCase):