gh-136297: Test all pickle protocols in test_zoneinfo_property.py

Author: sobolevn

Lib/test/test_zoneinfo/test_zoneinfo_property.py

@@ -146,17 +146,21 @@ def setUp(self):
     @add_key_examples
     def test_pickle_unpickle_cache(self, key):
         zi = self.klass(key)
-        pkl_str = pickle.dumps(zi)
-        zi_rt = pickle.loads(pkl_str)
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            with self.subTest(proto=proto):
+                pkl_str = pickle.dumps(zi, proto)
+                zi_rt = pickle.loads(pkl_str)
 
         self.assertIs(zi, zi_rt)
 
     @hypothesis.given(key=valid_keys())
     @add_key_examples
     def test_pickle_unpickle_no_cache(self, key):
         zi = self.klass.no_cache(key)
-        pkl_str = pickle.dumps(zi)
-        zi_rt = pickle.loads(pkl_str)
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            with self.subTest(proto=proto):
+                pkl_str = pickle.dumps(zi, proto)
+                zi_rt = pickle.loads(pkl_str)
 
         self.assertIsNot(zi, zi_rt)
         self.assertEqual(str(zi), str(zi_rt))