diff --git a/tests/auth/test_user.py b/tests/auth/test_user.py
index 5cc479ce..e3bbe2e6 100644
--- a/tests/auth/test_user.py
+++ b/tests/auth/test_user.py
@@ -1,9 +1,19 @@
 import unittest
 
-from a2a.auth.user import UnauthenticatedUser
+from inspect import isabstract
+
+from a2a.auth.user import UnauthenticatedUser, User
+
+
+class TestUser(unittest.TestCase):
+    def test_is_abstract(self):
+        self.assertTrue(isabstract(User))
 
 
 class TestUnauthenticatedUser(unittest.TestCase):
+    def test_is_user_subclass(self):
+        self.assertTrue(issubclass(UnauthenticatedUser, User))
+
     def test_is_authenticated_returns_false(self):
         user = UnauthenticatedUser()
         self.assertFalse(user.is_authenticated)