Add test for automatic UserMetadata creation

dandiapi/api/tests/test_users.py

@@ -352,3 +352,10 @@ def test_user_edu_auto_approve(user: User, api_client: APIClient, email: str, ex
     assert resp.status_code == 302
 
     assert user_metadata.status == expected_status
+
+
+@pytest.mark.django_db
+def test_user_auto_create_user_metadata():
+    """Test that UserMetadata is automatically created for new users."""
+    user = User.objects.create()
+    assert hasattr(user, 'metadata')