bpo-34248: Add filename to error raised in {gnu,ndbm}.open() (GH-8590)

Report the filename to the exception when raising {gdbm,dbm.ndbm}.error in
dbm.gnu.open() and dbm.ndbm.open() functions, so it gets printed when the
exception is raised, and can also be obtained by the filename attribute of the
exception object.

2 files changed, 13 insertions, 0 deletions

diff --git a/Lib/test/test_dbm_gnu.py b/Lib/test/test_dbm_gnu.py
index c96eff5..16b7fe6 100644
--- a/Lib/test/test_dbm_gnu.py
+++ b/Lib/test/test_dbm_gnu.py
@@ -144,6 +144,13 @@ class TestGdbm(unittest.TestCase):
             self.assertTrue(b'key' in db)
             self.assertEqual(db[b'key'], b'value')
 
+    def test_nonexisting_file(self):
+        nonexisting_file = 'nonexisting-file'
+        with self.assertRaises(gdbm.error) as cm:
+            gdbm.open(nonexisting_file)
+        self.assertIn(nonexisting_file, str(cm.exception))
+        self.assertEqual(cm.exception.filename, nonexisting_file)
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/Lib/test/test_dbm_ndbm.py b/Lib/test/test_dbm_ndbm.py
index 49b88f5..bd411da 100644
--- a/Lib/test/test_dbm_ndbm.py
+++ b/Lib/test/test_dbm_ndbm.py
@@ -105,6 +105,12 @@ class DbmTestCase(unittest.TestCase):
             self.assertTrue(b'key' in db)
             self.assertEqual(db[b'key'], b'value')
 
+    def test_nonexisting_file(self):
+        nonexisting_file = 'nonexisting-file'
+        with self.assertRaises(dbm.ndbm.error) as cm:
+            dbm.ndbm.open(nonexisting_file)
+        self.assertIn(nonexisting_file, str(cm.exception))
+        self.assertEqual(cm.exception.filename, nonexisting_file)
 
 
 if __name__ == '__main__':