3.8, 3.9 use collected parameters more explicitly

minor comment corrections

Author: Daraan

src/test_typing_extensions.py

@@ -7203,11 +7203,9 @@ def test_alias_types_and_substitutions(self):
             Unpack[Ts] : (Ts,),
             Unpack[Tuple[int, T2]] : (T2,),
             Concatenate[int,  P] : (P,),
+            # Not tested usage of bare TypeVarTuple, would need 3.11+
+            # Ts : (Ts,),  # invalid case
         }
-        test_argument_cases_311_plus = {
-            Ts : (Ts,),  # invalid case
-        }
-        test_argument_cases.update(test_argument_cases_311_plus)
 
         test_alias_cases = [
             # Simple cases
@@ -7241,8 +7239,6 @@ def test_alias_types_and_substitutions(self):
                 self.assertEqual(subscripted.__parameters__, ())
             for expected_args, expected_parameters in test_argument_cases.items():
                 with self.subTest(alias=alias, args=expected_args):
-                    if expected_args in test_argument_cases_311_plus and sys.version_info < (3, 11):
-                        self.skipTest("Case is not valid before 3.11")
                     self.assertEqual(get_args(alias[expected_args]), (expected_args,))
                     self.assertEqual(alias[expected_args].__parameters__, expected_parameters)
 
@@ -7419,9 +7415,9 @@ def test_wrong_amount_of_parameters(self):
                 self.assertEqual(get_args(alias), expected_args)
                 self.assertEqual(alias.__parameters__, expected_params)
 
-    # The condition should align with the version of GeneriAlias usage in __getitem__
+    # The condition should align with the version of GeneriAlias usage in __getitem__ or be 3.11+
     @skipIf(TYPING_3_10_0, "Most arguments are allowed in 3.11+ or with GenericAlias")
-    def test_invalid_cases_before_3_11(self):
+    def test_invalid_cases_before_3_10(self):
         T = TypeVar('T')
         ListOrSetT = TypeAliasType("ListOrSetT", Union[List[T], Set[T]], type_params=(T,))
         with self.assertRaises(TypeError):

src/typing_extensions.py

@@ -3577,7 +3577,7 @@ def _check_single_param(self, param, recursion=0):
                 # Allow [], [int], [int, str], [int, ...], [int, T]
                 if param is ...:
                     yield ...
-                # Note in < 3.9 _ConcatenateGenericAlias inherits from list
+                # Note in <= 3.9 _ConcatenateGenericAlias inherits from list
                 elif isinstance(param, list) and recursion == 0:
                     yield [checked
                            for arg in param
@@ -3611,9 +3611,10 @@ def __getitem__(self, parameters):
             type_vars = _collect_type_vars(parameters)
             parameters = self._check_parameters(parameters)
             alias = _TypeAliasGenericAlias(self, parameters)
-            # If Concatenate is present its parameters were not collected
-            if len(alias.__parameters__) < len(type_vars):
-                alias.__parameters__ = tuple(type_vars)
+            # alias.__parameters__ is not complete if Concatenate is present
+            # as it is converted to a list from which no parameters are extracted.
+            if alias.__parameters__ != type_vars:
+                alias.__parameters__ = type_vars
             return alias
 
         def __reduce__(self):