bpo-33106: change dbm key deletion error for readonly file from KeyError to dbm.error (#6295)

4 files changed, 26 insertions, 4 deletions

diff --git a/Lib/dbm/dumb.py b/Lib/dbm/dumb.py
index e5c17f5..6cef72a 100644
--- a/Lib/dbm/dumb.py
+++ b/Lib/dbm/dumb.py
@@ -185,7 +185,7 @@ class _Database(collections.abc.MutableMapping):
 
     def __setitem__(self, key, val):
         if self._readonly:
-            raise ValueError('The database is opened for reading only')
+            raise error('The database is opened for reading only')
         if isinstance(key, str):
             key = key.encode('utf-8')
         elif not isinstance(key, (bytes, bytearray)):
@@ -222,7 +222,7 @@ class _Database(collections.abc.MutableMapping):
 
     def __delitem__(self, key):
         if self._readonly:
-            raise ValueError('The database is opened for reading only')
+            raise error('The database is opened for reading only')
         if isinstance(key, str):
             key = key.encode('utf-8')
         self._verify_open()
diff --git a/Lib/test/test_dbm_dumb.py b/Lib/test/test_dbm_dumb.py
index 58b9d17..e8e827e 100644
--- a/Lib/test/test_dbm_dumb.py
+++ b/Lib/test/test_dbm_dumb.py
@@ -82,10 +82,10 @@ class DumbDBMTestCase(unittest.TestCase):
         self.init_db()
         f = dumbdbm.open(_fname, 'r')
         self.read_helper(f)
-        with self.assertRaisesRegex(ValueError,
+        with self.assertRaisesRegex(dumbdbm.error,
                                    'The database is opened for reading only'):
             f[b'g'] = b'x'
-        with self.assertRaisesRegex(ValueError,
+        with self.assertRaisesRegex(dumbdbm.error,
                                    'The database is opened for reading only'):
             del f[b'a']
         # get() works as in the dict interface
diff --git a/Lib/test/test_dbm_gnu.py b/Lib/test/test_dbm_gnu.py
index 16b7fe6..f1c7d34 100644
--- a/Lib/test/test_dbm_gnu.py
+++ b/Lib/test/test_dbm_gnu.py
@@ -131,6 +131,17 @@ class TestGdbm(unittest.TestCase):
             self.assertEqual(db['Unicode key \U0001f40d'],
                              'Unicode value \U0001f40d'.encode())
 
+    def test_write_readonly_file(self):
+        with gdbm.open(filename, 'c') as db:
+            db[b'bytes key'] = b'bytes value'
+        with gdbm.open(filename, 'r') as db:
+            with self.assertRaises(gdbm.error):
+                del db[b'not exist key']
+            with self.assertRaises(gdbm.error):
+                del db[b'bytes key']
+            with self.assertRaises(gdbm.error):
+                db[b'not exist key'] = b'not exist value'
+
     @unittest.skipUnless(TESTFN_NONASCII,
                          'requires OS support of non-ASCII encodings')
     def test_nonascii_filename(self):
diff --git a/Lib/test/test_dbm_ndbm.py b/Lib/test/test_dbm_ndbm.py
index bd411da..7ac75c5 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):