Misc type annotations (#1294)

Author: Carreau

ipykernel/kernelapp.py

@@ -16,6 +16,7 @@
 from io import FileIO, TextIOWrapper
 from logging import StreamHandler
 from pathlib import Path
+from typing import Optional
 
 import zmq
 from IPython.core.application import (  # type:ignore[attr-defined]
@@ -141,8 +142,9 @@ class IPKernelApp(BaseIPythonApplication, InteractiveShellApp, ConnectionFileMix
     debug_shell_socket = Any()
     stdin_socket = Any()
     iopub_socket = Any()
-    iopub_thread = Any()
-    control_thread = Any()
+
+    iopub_thread: Optional[IOPubThread] = Instance(IOPubThread, allow_none=True)  # type:ignore[assignment]
+    control_thread: Optional[ControlThread] = Instance(ControlThread, allow_none=True)  # type:ignore[assignment]
 
     _ports = Dict()
 
@@ -259,7 +261,7 @@ def _bind_socket(self, s, port):
                     raise
         return None
 
-    def write_connection_file(self):
+    def write_connection_file(self, **kwargs: t.Any) -> None:
         """write connection info to JSON file"""
         cf = self.abs_connection_file
         connection_info = dict(
@@ -398,11 +400,11 @@ def close(self):
         if self.heartbeat:
             self.log.debug("Closing heartbeat channel")
             self.heartbeat.context.term()
-        if self.iopub_thread:
+        if self.iopub_thread is not None:
             self.log.debug("Closing iopub channel")
             self.iopub_thread.stop()
             self.iopub_thread.close()
-        if self.control_thread and self.control_thread.is_alive():
+        if self.control_thread is not None and self.control_thread.is_alive():
             self.log.debug("Closing control thread")
             self.control_thread.stop()
             self.control_thread.join()

pyproject.toml

@@ -313,6 +313,8 @@ ignore = [
   "G002",
   # `open()` should be replaced by `Path.open()`
   "PTH123",
+  # use `X | Y` for type annotations, this does not works for dynamic getting type hints on older python
+  "UP007",
 ]
 unfixable = [
   # Don't touch print statements