Fix and add motion planner server tests

[methylDragon]

Builds on top of:

• Implement motion plan cache #16

I uncommented the old launch test, and discovered it was passing.

Then I tried adding a test for the motion plan cache, and had it fail because we need access to the robot joint state.

Turns out the old tests weren't loading a ros2_control controller, so I fixed it (maybe that's what broke in the first place?)

After building, test with:

clear && colcon test --packages-select nexus_motion_planner --event-handlers=console_direct+

[Yadunund]

Looks good. Minor comments. Should we also update the integration test CI job to run colcon test for this pkg?

[Yadunund]

Add <test_depend> for ros2_control pkgs.

[methylDragon]

51f34f4

[Yadunund]

What does the * do? Is it a pythonic way to append to a list?

[methylDragon]

The * unpacks the list into its composite elements (you can think of it as an extend() but in the middle of the list.

It was introduced to avoid "clunky syntax handling". https://peps.python.org/pep-3132/ , so I think it's acceptable.

The technically simpler way to do it would be:

    return launch.LaunchDescription([
        robot_state_publisher,
        motion_planner,
        move_group_node,
        static_tf_node_1,
        static_tf_node_2,
        trigger_lifecycle_1,
        trigger_lifecycle_2,
        trigger_lifecycle_3,
        trigger_lifecycle_4,
        trigger_lifecycle_5,
        trigger_lifecycle_6,
        trigger_get_plan_irb1300_poses,
        ros2_control_node]
  + load_controllers
  + [launch_testing.actions.ReadyToTest()
    ]), node_mapping

But I didn't like the triple addition.

[methylDragon]

I added the tests to CI b18e5b3