diff --git a/services/web/server/tests/unit/isolated/test_diagnostics.py b/services/web/server/tests/unit/isolated/test_diagnostics.py
index 3f18e81fd09..fdd08db062d 100644
--- a/services/web/server/tests/unit/isolated/test_diagnostics.py
+++ b/services/web/server/tests/unit/isolated/test_diagnostics.py
@@ -6,6 +6,7 @@
 from unittest.mock import Mock
 
 import pytest
+from pytest_mock import MockerFixture
 from servicelib.aiohttp.application_setup import APP_SETUP_COMPLETED_KEY
 from simcore_service_webserver.application_settings import setup_settings
 from simcore_service_webserver.diagnostics.plugin import setup_diagnostics
@@ -35,12 +36,14 @@ def add_routes(self, *args, **kwargs):
 
 
 @pytest.fixture
-def app_mock():
+def app_mock(mocker: MockerFixture):
     app = MockApp()
 
     # emulates security is initialized
     app[APP_SETUP_COMPLETED_KEY] = ["simcore_service_webserver.security"]
 
+    mocker.patch("simcore_service_webserver.rest.plugin.api_doc")
+
     return app