[3.13] gh-123881: Add additional test coverage for PEP 695 edge cases (GH-123886) (#123890)

gh-123881: Add additional test coverage for PEP 695 edge cases (GH-123886)
(cherry picked from commit b52de7e)

Co-authored-by: Jelle Zijlstra <[email protected]>

Author: miss-islington

Lib/test/test_type_params.py

@@ -950,6 +950,7 @@ class C[T](Base, a=1, b=2, **kwargs):
         T, = C.__type_params__
         self.assertEqual(T.__name__, "T")
         self.assertEqual(C.kwargs, {"a": 1, "b": 2, "c": 3})
+        self.assertEqual(C.__bases__, (Base, Generic))
 
         bases = (Base,)
         class C2[T](*bases, **kwargs):
@@ -958,6 +959,22 @@ class C2[T](*bases, **kwargs):
         T, = C2.__type_params__
         self.assertEqual(T.__name__, "T")
         self.assertEqual(C2.kwargs, {"c": 3})
+        self.assertEqual(C2.__bases__, (Base, Generic))
+
+    def test_starargs_base(self):
+        class C1[T](*()): pass
+
+        T, = C1.__type_params__
+        self.assertEqual(T.__name__, "T")
+        self.assertEqual(C1.__bases__, (Generic,))
+
+        class Base: pass
+        bases = [Base]
+        class C2[T](*bases): pass
+
+        T, = C2.__type_params__
+        self.assertEqual(T.__name__, "T")
+        self.assertEqual(C2.__bases__, (Base, Generic))
 
 
 class TypeParamsTraditionalTypeVarsTest(unittest.TestCase):