bpo-42355: symtable.get_namespace() now checks whether there are multiple or any namespaces found (GH-23278)

2 files changed, 11 insertions, 3 deletions

diff --git a/Lib/symtable.py b/Lib/symtable.py
index 922854b..75ff092 100644
--- a/Lib/symtable.py
+++ b/Lib/symtable.py
@@ -306,11 +306,15 @@ class Symbol:
     def get_namespace(self):
         """Return the single namespace bound to this name.
 
-        Raises ValueError if the name is bound to multiple namespaces.
+        Raises ValueError if the name is bound to multiple namespaces
+        or no namespace.
         """
-        if len(self.__namespaces) != 1:
+        if len(self.__namespaces) == 0:
+            raise ValueError("name is not bound to any namespaces")
+        elif len(self.__namespaces) > 1:
             raise ValueError("name is bound to multiple namespaces")
-        return self.__namespaces[0]
+        else:
+            return self.__namespaces[0]
 
 if __name__ == "__main__":
     import os, sys
diff --git a/Lib/test/test_symtable.py b/Lib/test/test_symtable.py
index a30e534..819354e 100644
--- a/Lib/test/test_symtable.py
+++ b/Lib/test/test_symtable.py
@@ -159,6 +159,10 @@ class SymtableTest(unittest.TestCase):
         self.assertEqual(len(ns_test.get_namespaces()), 2)
         self.assertRaises(ValueError, ns_test.get_namespace)
 
+        ns_test_2 = self.top.lookup("glob")
+        self.assertEqual(len(ns_test_2.get_namespaces()), 0)
+        self.assertRaises(ValueError, ns_test_2.get_namespace)
+
     def test_assigned(self):
         self.assertTrue(self.spam.lookup("x").is_assigned())
         self.assertTrue(self.spam.lookup("bar").is_assigned())