test_rclcpp :- Add local and async set_parameters_atomically tests

[Aaravanand00]

Description

This PR adds the missing tests for set_parameters_atomically to the test_rclcpp suite. It includes both local parameter assignment and remote asynchronous parameter assignment tests.

Changes included:

• Added test_set_parameters_atomically_async helper function to parameter_fixtures.hpp.
• Added local_set_parameters_atomically test case in test_local_parameters.cpp to verify atomic parameter assignment on a local node.
• Added asynchronous set_parameters_atomically tests to test_remote_parameters.cpp to verify remote atomic assignment (both for regular parameters and strict parameters_must_declare nodes).

Fixes #282

Is this user-facing behavior change?

Did you use Generative AI?

Yes, this pull request was generated with the assistance of Antigravity (a generative AI assistant ) to implement the test logic and boilerplate.

Additional Information

All newly added integration tests successfully pass locally against the Jazzy distribution in a WSL2 Ubuntu 24.04 environment.

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[fujitatomoya]

the original issue is almost 8 years ago, but this test case is still missing. lgtm. thanks for the contribution.

[fujitatomoya]

sorry, can you target this against rolling branch? that is where we develop as mainline.

[Aaravanand00]

sorry, can you target this against rolling branch? that is where we develop as mainline.

done ptal

[Aaravanand00]

the original issue is almost 8 years ago, but this test case is still missing. lgtm. thanks for the contribution.

is there any other test that you should want me to resolve first then let me know

[fujitatomoya]

Pulls: #595
Gist: https://gist.githubusercontent.com/fujitatomoya/84ab0104e7b32755bfe16770af5c560a/raw/d487a8e4e11062dabae98967ff9c1f37b0c0e00f/ros2.repos
BUILD args: --packages-up-to test_rclcpp
TEST args: --packages-select test_rclcpp
ROS Distro: rolling
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/19689

• Linux
• Linux-aarch64
• Linux-rhel
• Windows

[Aaravanand00]

@fujitatomoya Thank you for the review and approval I see the CI jobs returned unstable which seems to be due to existing flaky tests in the repository rather than these changes. Please let me know if there is anything else you need from my side before this can be merged......