[HaClient] Fix test race condition

According to the logs of the recent test failure, there's a small window when we test the connection is established where we have a socket connected but don't have the session created yet, and this is throwing exception when trying to disconnect because the renew loop is not yet created.

This is caused by the HaManager (in charge of connecting/reconnecting the clients) running in its own task, thus we're not in the usual await connect(); await disconnect() scenario.
This can also arguably be fixed at the client level by checking if
the renew loop exist on disconnect.

tests/conftest.py

@@ -11,6 +11,7 @@ from contextlib import closing
 
 from asyncua import Client
 from asyncua import Server, ua
+from asyncua.client.ua_client import UASocketProtocol
 from asyncua.client.ha.ha_client import HaClient, HaConfig, HaMode
 from asyncua.server.history import HistoryDict
 from asyncua.server.history_sql import HistorySQLite
@@ -390,7 +391,13 @@ async def wait_clients_socket(ha_client, state):
     for client in ha_client.get_clients():
         for _ in range(RETRY):
             if client.uaclient.protocol and client.uaclient.protocol.state == state:
-                break
+                # for connection OPEN, also wait for the session to be established
+                # otherwise we can encounter failure on disconnect
+                if state == UASocketProtocol.OPEN:
+                    if client._renew_channel_task:
+                        break
+                else:
+                    break
             await sleep(SLEEP)
         assert client.uaclient.protocol.state == state