Add unit test

Author: hyongtao-code

Lib/test/test_typing.py

@@ -10029,6 +10029,12 @@ def test_basic_with_exec(self):
         self.assertEqual(P.__name__, 'P')
         self.assertIs(P.__module__, None)
 
+    def test_bound(self):
+        P1 = ParamSpec("P1")     
+        P2 = ParamSpec("P2", bound=None)
+        self.assertIs(P1.__bound__, None)
+        self.assertIs(P2.__bound__, None)
+
     def test_valid_uses(self):
         P = ParamSpec('P')
         T = TypeVar('T')