[CI] test_get_topics_names_and_types_tool_with_readable_topic failed on humble

[Juliaj]

Describe the bug
The test_get_topics_names_and_types_tool_with_readable_topic failed because when readable=["/rosout"] was set, /rosout didn't appear in the response. The tool only showed "Writable topics:" even though /rosout was expected.

To Reproduce
This showed up in PR #701 CI, https://github.com/RobotecAI/rai/actions/runs/19401097295/job/55508700595?pr=701

 =========================== short test summary info ============================
FAILED tests/tools/ros2/test_topic_tools.py::test_get_topics_names_and_types_tool_with_readable_topic - AssertionError: assert '/rosout' in '\nWritable topics:topic: /parameter_events\ntype: rcl_interfaces/msg/ParameterEvent\n\ntopic: /tf\ntype: tf2_msgs/msg/TFMessage\n\ntopic: /tf_static\ntype: tf2_msgs/msg/TFMessage\n'
= 1 failed, 457 passed, 5 skipped, 9 xfailed, 8 warnings in 255.84s (0:04:15) ==
Error: Process completed with exit code 1.

Platform

• OS: [e.g. Ubuntu 22.04]
• ROS 2 Version [e.g. humble]
• Other information you think might be relevant such as graphic card, drivers etc.

Additional context
It appears that the failure is intermittent (?). The current hypothesis is that on humble, /rosout may not appear in get_topic_names_and_types() unless a node is actively publishing to it. In Jazzy, it may be included by default or discovered differently.

While looking at the source code, it is interesting that readable/writable concepts are defined as a mechanism for whitelist/permission control.

[maciejmajek]

This test is flaky. It fails on random occasions. I don't know the reason unfortunately. Afaik /rosout topic is always active as long the ros2 daemon is on.