gh-106263: Fix segfault in `signaldict_repr` in `_decimal` module (#106270)

Co-authored-by: sunmy2019 <59365878+sunmy2019@users.noreply.github.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/Lib/test/test_decimal.py b/Lib/test/test_decimal.py
index db67f37..fc66a30 100644
--- a/Lib/test/test_decimal.py
+++ b/Lib/test/test_decimal.py
@@ -5701,6 +5701,36 @@ class CWhitebox(unittest.TestCase):
         ContextManager = type(C.localcontext())
         check_disallow_instantiation(self, ContextManager)
 
+    def test_c_signaldict_segfault(self):
+        # See gh-106263 for details.
+        SignalDict = type(C.Context().flags)
+        sd = SignalDict()
+        err_msg = "invalid signal dict"
+
+        with self.assertRaisesRegex(ValueError, err_msg):
+            len(sd)
+
+        with self.assertRaisesRegex(ValueError, err_msg):
+            iter(sd)
+
+        with self.assertRaisesRegex(ValueError, err_msg):
+            repr(sd)
+
+        with self.assertRaisesRegex(ValueError, err_msg):
+            sd[C.InvalidOperation] = True
+
+        with self.assertRaisesRegex(ValueError, err_msg):
+            sd[C.InvalidOperation]
+
+        with self.assertRaisesRegex(ValueError, err_msg):
+            sd == C.Context().flags
+
+        with self.assertRaisesRegex(ValueError, err_msg):
+            C.Context().flags == sd
+
+        with self.assertRaisesRegex(ValueError, err_msg):
+            sd.copy()
+
 @requires_docstrings
 @requires_cdecimal
 class SignatureTest(unittest.TestCase):