Test all protocols

Author: mauvilsa

Lib/test/test_argparse.py

@@ -88,15 +88,17 @@ def test_pickle_roundtrip(self):
         parser = argparse.ArgumentParser(exit_on_error=False)
         parser.add_argument('--foo', type=int, default=42)
         parser.add_argument('bar', nargs='?', default='baz')
-        # Try to pickle and unpickle the parser
-        parser2 = pickle.loads(pickle.dumps(parser))
-        # Check that the round-tripped parser still works
-        ns = parser2.parse_args(['--foo', '123', 'quux'])
-        self.assertEqual(ns.foo, 123)
-        self.assertEqual(ns.bar, 'quux')
-        ns2 = parser2.parse_args([])
-        self.assertEqual(ns2.foo, 42)
-        self.assertEqual(ns2.bar, 'baz')
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            with self.subTest(protocol=proto):
+                # Try to pickle and unpickle the parser
+                parser2 = pickle.loads(pickle.dumps(parser, protocol=proto))
+                # Check that the round-tripped parser still works
+                ns = parser2.parse_args(['--foo', '123', 'quux'])
+                self.assertEqual(ns.foo, 123)
+                self.assertEqual(ns.bar, 'quux')
+                ns2 = parser2.parse_args([])
+                self.assertEqual(ns2.foo, 42)
+                self.assertEqual(ns2.bar, 'baz')
 
 
 class TestCase(unittest.TestCase):