test: add assertIs/assertIsNot shims to HumanNameTestBase

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: derek73

tests/base.py

@@ -41,3 +41,9 @@ def assertIn(self, member: object, container: object, msg: object = None) -> Non
 
     def assertNotIn(self, member: object, container: object, msg: object = None) -> None:
         assert member not in container, msg  # type: ignore[operator]
+
+    def assertIs(self, first: object, second: object, msg: object = None) -> None:
+        assert first is second, msg or f"{first!r} is not {second!r}"
+
+    def assertIsNot(self, first: object, second: object, msg: object = None) -> None:
+        assert first is not second, msg or f"{first!r} is {second!r}"