diff --git a/ipykernel/kernelbase.py b/ipykernel/kernelbase.py
index 2b5b63e5..7c65ef2c 100644
--- a/ipykernel/kernelbase.py
+++ b/ipykernel/kernelbase.py
@@ -551,7 +551,9 @@ async def start(self, *, task_status: TaskStatus = TASK_STATUS_IGNORED) -> None:
                 # Assign tasks to and start shell channel thread.
                 manager = self.shell_channel_thread.manager
                 self.shell_channel_thread.add_task(self.shell_channel_thread_main)
-                self.shell_channel_thread.add_task(manager.listen_from_control, self.shell_main, self.shell_channel_thread)
+                self.shell_channel_thread.add_task(
+                    manager.listen_from_control, self.shell_main, self.shell_channel_thread
+                )
                 self.shell_channel_thread.add_task(manager.listen_from_subshells)
                 self.shell_channel_thread.start()
             else:
@@ -1081,7 +1083,9 @@ async def create_subshell_request(self, socket, ident, parent) -> None:
 
         # This should only be called in the control thread if it exists.
         # Request is passed to shell channel thread to process.
-        other_socket = await self.shell_channel_thread.manager.get_control_other_socket(self.control_thread.get_task_group())
+        other_socket = await self.shell_channel_thread.manager.get_control_other_socket(
+            self.control_thread.get_task_group()
+        )
         await other_socket.asend_json({"type": "create"})
         reply = await other_socket.arecv_json()
 
@@ -1103,7 +1107,9 @@ async def delete_subshell_request(self, socket, ident, parent) -> None:
 
         # This should only be called in the control thread if it exists.
         # Request is passed to shell channel thread to process.
-        other_socket = await self.shell_channel_thread.manager.get_control_other_socket(self.control_thread.get_task_group())
+        other_socket = await self.shell_channel_thread.manager.get_control_other_socket(
+            self.control_thread.get_task_group()
+        )
         await other_socket.asend_json({"type": "delete", "subshell_id": subshell_id})
         reply = await other_socket.arecv_json()
 
@@ -1118,7 +1124,9 @@ async def list_subshell_request(self, socket, ident, parent) -> None:
 
         # This should only be called in the control thread if it exists.
         # Request is passed to shell channel thread to process.
-        other_socket = await self.shell_channel_thread.manager.get_control_other_socket(self.control_thread.get_task_group())
+        other_socket = await self.shell_channel_thread.manager.get_control_other_socket(
+            self.control_thread.get_task_group()
+        )
         await other_socket.asend_json({"type": "list"})
         reply = await other_socket.arecv_json()
 
diff --git a/ipykernel/subshell_manager.py b/ipykernel/subshell_manager.py
index 46832c99..66e31fd8 100644
--- a/ipykernel/subshell_manager.py
+++ b/ipykernel/subshell_manager.py
@@ -40,7 +40,12 @@ class SubshellManager:
     against multiple subshells attempting to send at the same time.
     """
 
-    def __init__(self, context: zmq.Context, shell_socket: zmq_anyio.Socket, get_task_group: Callable[[], TaskGroup]):
+    def __init__(
+        self,
+        context: zmq.Context,
+        shell_socket: zmq_anyio.Socket,
+        get_task_group: Callable[[], TaskGroup],
+    ):
         assert current_thread() == main_thread()
 
         self._context: zmq.Context = context
@@ -229,7 +234,9 @@ def _is_subshell(self, subshell_id: str | None) -> bool:
         with self._lock_cache:
             return subshell_id in self._cache
 
-    async def _listen_for_subshell_reply(self, subshell_id: str | None, task_group: TaskGroup) -> None:
+    async def _listen_for_subshell_reply(
+        self, subshell_id: str | None, task_group: TaskGroup
+    ) -> None:
         """Listen for reply messages on specified subshell inproc socket and
         resend to the client via the shell_socket.
 
diff --git a/tests/conftest.py b/tests/conftest.py
index dfa7df5d..c981f867 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -22,10 +22,11 @@
     resource = None  # type:ignore
 
 
-@pytest.fixture
+@pytest.fixture()
 def anyio_backend():
     return "asyncio"
 
+
 pytestmark = pytest.mark.anyio