Don't subscribe with Transient local QoS when there are volatile publishers (#1023)

* fix: incompatible QoS settings for subs

for reliability, if any subscribed topic has a non-reliable policy, we set reliability to best effort. for durability, if if any subscribed topic has a non-transient-local policy, we set durability to volatile.

* fix: define variables

* fix: lint and remove default publisher qos durability setting

* fix: default durability policy for tests

* fix: code fixed according to recommendation

* fix: lint

* fix: added recommended changes

* fix: reverted test changes

* fix: check if there are any publisher.

* fix: lint

* fix: qos settings

* fix: requested changes

Author: Egoless41

rosbridge_library/src/rosbridge_library/internal/subscribers.py

@@ -120,7 +120,10 @@ def __init__(self, topic, client_id, callback, node_handle, msg_type=None, raw=F
         )
 
         infos = node_handle.get_publishers_info_by_topic(topic)
-        if any(pub.qos_profile.durability == DurabilityPolicy.TRANSIENT_LOCAL for pub in infos):
+
+        if len(infos) > 0 and all(
+            pub.qos_profile.durability == DurabilityPolicy.TRANSIENT_LOCAL for pub in infos
+        ):
             qos.durability = DurabilityPolicy.TRANSIENT_LOCAL
             qos.reliability = ReliabilityPolicy.RELIABLE
         if any(pub.qos_profile.reliability == ReliabilityPolicy.BEST_EFFORT for pub in infos):
@@ -182,10 +185,14 @@ def subscribe(self, client_id, callback):
             # which adds the new callback to the subscriptions dictionary.
             self.new_subscriptions.update({client_id: callback})
             infos = self.node_handle.get_publishers_info_by_topic(self.topic)
-            if any(pub.qos_profile.durability == DurabilityPolicy.TRANSIENT_LOCAL for pub in infos):
+
+            if len(infos) > 0 and all(
+                pub.qos_profile.durability == DurabilityPolicy.TRANSIENT_LOCAL for pub in infos
+            ):
                 self.qos.durability = DurabilityPolicy.TRANSIENT_LOCAL
             if any(pub.qos_profile.reliability == ReliabilityPolicy.BEST_EFFORT for pub in infos):
                 self.qos.reliability = ReliabilityPolicy.BEST_EFFORT
+
             if self.new_subscriber is None:
                 self.new_subscriber = self.node_handle.create_subscription(
                     self.msg_class,