bpo-33383: Fix crash in get() of the dbm.ndbm database object. (#6630)

4 files changed, 31 insertions, 2 deletions

diff --git a/Lib/test/test_dbm.py b/Lib/test/test_dbm.py
index f0a428d..fb89807 100644
--- a/Lib/test/test_dbm.py
+++ b/Lib/test/test_dbm.py
@@ -86,12 +86,21 @@ class AnyDBMTestCase:
         f = dbm.open(_fname, 'c')
         self._dict['g'] = f[b'g'] = b"indented"
         self.read_helper(f)
+        # setdefault() works as in the dict interface
+        self.assertEqual(f.setdefault(b'xxx', b'foo'), b'foo')
+        self.assertEqual(f[b'xxx'], b'foo')
         f.close()
 
     def test_anydbm_read(self):
         self.init_db()
         f = dbm.open(_fname, 'r')
         self.read_helper(f)
+        # get() works as in the dict interface
+        self.assertEqual(f.get(b'a'), self._dict['a'])
+        self.assertEqual(f.get(b'xxx', b'foo'), b'foo')
+        self.assertIsNone(f.get(b'xxx'))
+        with self.assertRaises(KeyError):
+            f[b'xxx']
         f.close()
 
     def test_anydbm_keys(self):
diff --git a/Lib/test/test_dbm_dumb.py b/Lib/test/test_dbm_dumb.py
index 652a355..58b9d17 100644
--- a/Lib/test/test_dbm_dumb.py
+++ b/Lib/test/test_dbm_dumb.py
@@ -73,6 +73,9 @@ class DumbDBMTestCase(unittest.TestCase):
         f = dumbdbm.open(_fname, 'w')
         self._dict[b'g'] = f[b'g'] = b"indented"
         self.read_helper(f)
+        # setdefault() works as in the dict interface
+        self.assertEqual(f.setdefault(b'xxx', b'foo'), b'foo')
+        self.assertEqual(f[b'xxx'], b'foo')
         f.close()
 
     def test_dumbdbm_read(self):
@@ -85,6 +88,12 @@ class DumbDBMTestCase(unittest.TestCase):
         with self.assertRaisesRegex(ValueError,
                                    'The database is opened for reading only'):
             del f[b'a']
+        # get() works as in the dict interface
+        self.assertEqual(f.get(b'a'), self._dict[b'a'])
+        self.assertEqual(f.get(b'xxx', b'foo'), b'foo')
+        self.assertIsNone(f.get(b'xxx'))
+        with self.assertRaises(KeyError):
+            f[b'xxx']
         f.close()
 
     def test_dumbdbm_keys(self):
diff --git a/Lib/test/test_dbm_gnu.py b/Lib/test/test_dbm_gnu.py
index d96df92..463d343 100644
--- a/Lib/test/test_dbm_gnu.py
+++ b/Lib/test/test_dbm_gnu.py
@@ -32,9 +32,12 @@ class TestGdbm(unittest.TestCase):
             self.assertIn(key, key_set)
             key_set.remove(key)
             key = self.g.nextkey(key)
-        self.assertRaises(KeyError, lambda: self.g['xxx'])
         # get() and setdefault() work as in the dict interface
+        self.assertEqual(self.g.get(b'a'), b'b')
+        self.assertIsNone(self.g.get(b'xxx'))
         self.assertEqual(self.g.get(b'xxx', b'foo'), b'foo')
+        with self.assertRaises(KeyError):
+            self.g['xxx']
         self.assertEqual(self.g.setdefault(b'xxx', b'foo'), b'foo')
         self.assertEqual(self.g[b'xxx'], b'foo')
 
diff --git a/Lib/test/test_dbm_ndbm.py b/Lib/test/test_dbm_ndbm.py
index fb7d0e8..f921167 100644
--- a/Lib/test/test_dbm_ndbm.py
+++ b/Lib/test/test_dbm_ndbm.py
@@ -18,7 +18,7 @@ class DbmTestCase(unittest.TestCase):
 
     def test_keys(self):
         self.d = dbm.ndbm.open(self.filename, 'c')
-        self.assertTrue(self.d.keys() == [])
+        self.assertEqual(self.d.keys(), [])
         self.d['a'] = 'b'
         self.d[b'bytes'] = b'data'
         self.d['12345678910'] = '019237410982340912840198242'
@@ -26,6 +26,14 @@ class DbmTestCase(unittest.TestCase):
         self.assertIn('a', self.d)
         self.assertIn(b'a', self.d)
         self.assertEqual(self.d[b'bytes'], b'data')
+        # get() and setdefault() work as in the dict interface
+        self.assertEqual(self.d.get(b'a'), b'b')
+        self.assertIsNone(self.d.get(b'xxx'))
+        self.assertEqual(self.d.get(b'xxx', b'foo'), b'foo')
+        with self.assertRaises(KeyError):
+            self.d['xxx']
+        self.assertEqual(self.d.setdefault(b'xxx', b'foo'), b'foo')
+        self.assertEqual(self.d[b'xxx'], b'foo')
         self.d.close()
 
     def test_modes(self):