nav2_system_tests: ensure error_msg not empty (ros-navigation#4341)

Signed-off-by: Mike Wake <michael.wake@aosgrp.com.au>

nav2_system_tests/src/error_codes/test_error_codes.py

@@ -79,6 +79,9 @@ def main(argv=sys.argv[1:]):
             assert (
                 navigator.result_future.result().result.error_code == error_code
             ), 'Follow path error code does not match'
+            assert (
+                navigator.result_future.result().result.error_msg != ""
+            ), 'Follow path error_msg is empty'
 
         else:
             assert False, 'Follow path was rejected'
@@ -111,6 +114,9 @@ def main(argv=sys.argv[1:]):
         assert (
             result.error_code == error_code
         ), 'Compute path to pose error does not match'
+        assert (
+            result.error_msg != ""
+        ), 'Compute path to pose error_msg empty'
 
     def cancel_task():
         time.sleep(1)
@@ -145,6 +151,9 @@ def cancel_task():
         assert (
             result.error_code == error_code
         ), 'Compute path through pose error does not match'
+        assert (
+            result.error_msg != ""
+        ), 'Compute path through pose error_msg is empty'
     # Check compute path to pose cancel
     threading.Thread(target=cancel_task).start()
     result = navigator._getPathThroughPosesImpl(initial_pose, goal_poses, 'cancelled')
@@ -182,6 +191,7 @@ def cancel_task():
     for smoother, error_code in smoother.items():
         result = navigator._smoothPathImpl(a_path, smoother)
         assert result.error_code == error_code, 'Smoother error does not match'
+        assert result.error_msg != "", 'Smoother error_msg is empty'
 
     navigator.lifecycleShutdown()
     rclpy.shutdown()

nav2_system_tests/src/gps_navigation/tester.py

@@ -190,6 +190,9 @@ def main(argv=sys.argv[1:]):
         test.action_result.missed_waypoints[0].error_code
         == ComputePathToPose.Result().GOAL_OUTSIDE_MAP
     )
+    assert (
+        test.action_result.missed_waypoints[0].error_msg != ""
+    )
 
     # stop on failure test with bogous waypoint
     test.setStopFailureParam(True)

nav2_system_tests/src/waypoint_follower/tester.py

@@ -241,6 +241,7 @@ def main(argv=sys.argv[1:]):
         test.action_result.missed_waypoints[0].error_code
         == ComputePathToPose.Result().GOAL_OUTSIDE_MAP
     )
+    assert (test.action_result.missed_waypoints[0].error_msg != "")
 
     # stop on failure test with bogous waypoint
     test.setStopFailureParam(True)