WaitForTopics: wait for publisher-subscriber connection to be established (#474)

Signed-off-by: Giorgio Pintaudi <[email protected]>
Signed-off-by: Giorgio Pintaudi <[email protected]>

Author: LastStarDust

launch_testing_ros/launch_testing_ros/wait_for_topics.py

@@ -63,7 +63,7 @@ def method_3():
             topic_list = [('topic_1', String), ('topic_2', String)]
             wait_for_topics = WaitForTopics(topic_list, timeout=5.0, trigger=trigger_function)
             # The trigger function will be called inside the wait() method after the
-            # subscribers are created and before the publishers are connected.
+            # subscribers are created and the publishers are connected.
             assert wait_for_topics.wait("Hello World!")
             print('Given topics are receiving messages !')
             wait_for_topics.shutdown()
@@ -108,9 +108,9 @@ def _prepare_ros_node(self):
 
     def wait(self, *args, **kwargs):
         self.__ros_node.start_subscribers(self.topic_tuples)
+        self.__ros_node.any_publisher_connected.wait(self.timeout)
         if self.trigger:
             self.trigger(self.__ros_node, *args, **kwargs)
-        self.__ros_node.any_publisher_connected.wait(self.timeout)
         return self.__ros_node.msg_event_object.wait(self.timeout)
 
     def shutdown(self):