remote: make start_session() args more explicit

During the move to gRPC, start_session()'s arguments changed. Since this
is one of the functions used from outside of labgrid, add typing hints
and force the kwargs to be passed with names. This should make users
aware of the changes, so their code can be adapted.

Signed-off-by: Bastian Krause <bst@pengutronix.de>

labgrid/remote/client.py

@@ -23,6 +23,7 @@
 from collections import defaultdict, OrderedDict
 from datetime import datetime
 from pprint import pformat
+from typing import Any, Dict
 
 import attr
 import grpc
@@ -1566,7 +1567,19 @@ def ensure_event_loop(external_loop=None):
     return loop
 
 
-def start_session(address, extra=None, debug=False, loop=None):
+def start_session(
+    address: str, *, extra: Dict[str, Any] = None, debug: bool = False, loop: "asyncio.AbstractEventLoop | None" = None
+):
+    """
+    Starts a ClientSession.
+
+    Args:
+        address: coordinator address as HOST[:PORT], PORT defaults to 20408
+        extra: additional kwargs for ClientSession
+        debug: set debug mode of the event loop
+        loop: explicit event loop to use (otherwise a previously stashed loop,
+              if retrievable the current thread's loop or a new loop is used)
+    """
     loop = ensure_event_loop(loop)
 
     if extra is None:

labgrid/resource/remote.py

@@ -22,7 +22,7 @@ def _start(self):
 
         from ..remote.client import start_session
         try:
-            self.session = start_session(self.url, {'env': self.env})
+            self.session = start_session(self.url, extra={'env': self.env})
         except ConnectionRefusedError as e:
             raise ConnectionRefusedError(f"Could not connect to coordinator {self.url}") \
                 from e