Parent is now mandatory when creating a new BaseInstance class

tests/controls/conftest.py

@@ -1,5 +1,7 @@
 import pytest
 
+from myfasthtml.core.instances import SingleInstance
+
 
 @pytest.fixture(scope="session")
 def session():
@@ -14,3 +16,8 @@ def session():
           'updated_at': '2025-11-10T15:52:59.006213'
       }
   }
+
+
+@pytest.fixture(scope="session")
+def root_instance(session):
+  return SingleInstance(session, "TestRoot", None)

tests/controls/test_tabsmanager.py

@@ -4,13 +4,13 @@ from fasthtml.xtend import Script
 
 from myfasthtml.controls.TabsManager import TabsManager
 from myfasthtml.core.instances import InstancesManager
-from myfasthtml.test.matcher import matches, NoChildren, StartsWith
+from myfasthtml.test.matcher import matches, NoChildren
 from .conftest import session
 
 
 @pytest.fixture()
-def tabs_manager(session):
-  yield TabsManager(session)
+def tabs_manager(root_instance):
+  yield TabsManager(root_instance)
   
   InstancesManager.reset()
 
@@ -113,7 +113,7 @@ class TestTabsManagerRender:
         id=f"{tabs_manager.get_id()}-header-wrapper"
       ),
       Div(
-        Div(id=StartsWith(tabs_manager.get_id())),
+        Div("Content 3"), # active tab content
         # Lasy loading for the other contents
         id=f"{tabs_manager.get_id()}-content-wrapper"
       ),