1 files changed, 11 insertions, 0 deletions
diff --git a/Lib/test/test_dbm_ndbm.py b/Lib/test/test_dbm_ndbm.py
index bd411da652..7ac75c5fea 100644
--- a/Lib/test/test_dbm_ndbm.py
+++ b/Lib/test/test_dbm_ndbm.py
@@ -90,6 +90,17 @@ class DbmTestCase(unittest.TestCase):
             self.assertEqual(db['Unicode key \U0001f40d'],
                              'Unicode value \U0001f40d'.encode())
 
+    def test_write_readonly_file(self):
+        with dbm.ndbm.open(self.filename, 'c') as db:
+            db[b'bytes key'] = b'bytes value'
+        with dbm.ndbm.open(self.filename, 'r') as db:
+            with self.assertRaises(error):
+                del db[b'not exist key']
+            with self.assertRaises(error):
+                del db[b'bytes key']
+            with self.assertRaises(error):
+                db[b'not exist key'] = b'not exist value'
+
     @unittest.skipUnless(support.TESTFN_NONASCII,
                          'requires OS support of non-ASCII encodings')
     def test_nonascii_filename(self):