support classic notebook server in test extension

jupyterhub/tests/extension/__init__.py

@@ -6,7 +6,15 @@ state we want to check about the server
 
 import json
 
-from jupyter_server.base.handlers import JupyterHandler
+try:
+    from jupyter_server.base.handlers import JupyterHandler
+except ImportError:
+    from notebook.base.handlers import IPythonHandler as JupyterHandler
+
+    is_notebook_classic = True
+else:
+    is_notebook_classic = False
+
 from tornado import web
 
 
@@ -54,3 +62,8 @@ def _load_jupyter_server_extension(serverapp):
         )
     ]
     serverapp.web_app.add_handlers('.*$', handlers)
+
+
+# classic notebook (<7) name
+if is_notebook_classic:
+    load_jupyter_server_extension = _load_jupyter_server_extension

pyproject.toml

@@ -37,7 +37,7 @@ Tracker = "https://github.com/jupyterhub/jupyterhub/issues"
 
 [project.optional-dependencies]
 # note: updating test dependencies here
-# may require updating files in ci/oldest-dependencies/
+# may require matching updates in ci/oldest-dependencies/
 test = [
   "beautifulsoup4[html5lib]",
   "coverage",