[launch_pytest] RegisterEventHandler / OnProcessExit not processed correctly.

Bug report

Required Info:

• Operating System:
  • Ubuntu 22.04
• Installation type:
  • Docker
• Version or commit hash:
  • ros:rolling-ros-core-jammy
• Client library (if applicable):
  • launch_pytest

Steps to reproduce issue

I have a launch file with some action that starts other nodes when one exits.

on_station_setup_exit = RegisterEventHandler(
    OnProcessExit(
        target_action=station_setup_node,
        on_exit=[
            joint_state_publisher,
        ],
    )
)

I am creating a launch description for test using that launch file.

full_station_launch = IncludeLaunchDescription(
    PythonLaunchDescriptionSource(
        [pylon_pkg_prefix, "/launch/station.launch.py"]
    )
)

I am currently trying to port from launch_testing to launch_pytest. Everything worked fine with the previous package, but the joint_state_publisher never launches with the new setup. Everything runs if I remove the RegisterEventHandler bit from the launch file and add to launch_description directly. Looking at the launch log output, I can see that station_setup_node exits but joint_state_publisher never starts.

Any pointers would be a huge help, Thanks!

Start by reproducing the launch_pytest setup with the included Python launch description, RegisterEventHandler, and OnProcessExit shown in the report. Trace how the included description processes the event handler, then verify that joint_state_publisher starts after station_setup_node exits; the issue is done when this behavior matches the direct launch-description setup.