fix: resolve flaky test_resource_change_notifier and Humble demo node SIGSEGV

[bburda]

Pull Request

Summary

Fix two flaky CI failures on main:

1. test_resource_change_notifier timeout (Rolling): Reorder variable declarations in all 16 tests so ResourceChangeNotifier is declared after shared state (promises, atomics). C++ destroys locals in reverse declaration order, so the notifier's worker thread is now shut down before any captured variable is destroyed - preventing use-after-free when wait_for times out under CI load.

2. test_hybrid_suppression SIGSEGV on Humble: Fix demo node destructors to reset subscriptions and timers before implicit member destruction, and restructure main() to explicitly destroy the node before rclcpp::shutdown(). This reduces the SIGINT teardown race window that caused SIGSEGV (exit -11) on Humble.

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Issue

• closes [BUG] Flaky CI: test_resource_change_notifier timeout + test_hybrid_suppression SIGSEGV on Humble #344

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Type

• Bug fix
• New feature or tests
• Breaking change
• Documentation only

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Testing

• All 2413 unit tests pass locally on Jazzy
• test_resource_change_notifier specifically passes (16/16 tests)
• Demo nodes compile and link correctly
• Pre-commit hooks pass (clang-format, ament-copyright, etc.)
• Humble SIGSEGV fix requires CI verification (not reproducible locally on Jazzy)

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Checklist

• Breaking changes are clearly described (and announced in docs / changelog if needed)
• Tests were added or updated if needed
• Docs were updated if behavior or public API changed

[Copilot]

Pull request overview

Fixes two CI flakes affecting ros2_medkit’s gateway unit tests (Rolling) and integration-test demo nodes (Humble), improving shutdown/teardown safety around background threads and ROS 2 node destruction.

Changes:

• Reorders local declarations in test_resource_change_notifier so ResourceChangeNotifier is destroyed before callback-captured shared state, preventing use-after-free hangs on timeouts.
• Hardens integration-test demo nodes’ shutdown by explicitly destroying the node before rclcpp::shutdown() and resetting timers/subscriptions in destructors to reduce teardown races/SIGSEGVs on Humble.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/ros2_medkit_integration_tests/demo_nodes/rpm_sensor.cpp	Reset timer in destructor; ensure node is destroyed before rclcpp::shutdown().
src/ros2_medkit_integration_tests/demo_nodes/param_beacon_node.cpp	Ensure node is destroyed before rclcpp::shutdown().
src/ros2_medkit_integration_tests/demo_nodes/light_controller.cpp	Reset subscription/timer in destructor; ensure node is destroyed before rclcpp::shutdown().
src/ros2_medkit_integration_tests/demo_nodes/lidar_sensor.cpp	Reset timers in destructor; ensure node is destroyed before rclcpp::shutdown().
src/ros2_medkit_integration_tests/demo_nodes/engine_temp_sensor.cpp	Reset timer in destructor; ensure node is destroyed before rclcpp::shutdown().
src/ros2_medkit_integration_tests/demo_nodes/door_status_sensor.cpp	Reset timer in destructor; ensure node is destroyed before rclcpp::shutdown().
src/ros2_medkit_integration_tests/demo_nodes/calibration_service.cpp	Ensure node is destroyed before rclcpp::shutdown().
src/ros2_medkit_integration_tests/demo_nodes/brake_pressure_sensor.cpp	Reset timer in destructor; ensure node is destroyed before rclcpp::shutdown().
src/ros2_medkit_integration_tests/demo_nodes/brake_actuator.cpp	Reset subscription/timer in destructor; ensure node is destroyed before rclcpp::shutdown().
src/ros2_medkit_integration_tests/demo_nodes/beacon_publisher.cpp	Add destructor to cancel/reset timer; ensure node is destroyed before rclcpp::shutdown().
src/ros2_medkit_gateway/test/test_resource_change_notifier.cpp	Reorder declarations across tests so notifier teardown joins worker thread before shared state is destroyed.