Add integration tests for updateVelocity / updateOrientation callback paths

[rolker]

Summary

Add end-to-end integration tests for MRUTransform::updateVelocity and
updateOrientation that exercise the actual callback code path —
TF lookups, rotation application, failure handling, publishing —
rather than only the rotation math in isolation.

Background

PR #19 added test_twist_rotation.cpp which covers
rotate_covariance_block_3x3 with hand-computed expected outputs.
That is good coverage for the math itself, but it doesn't exercise:

• updateVelocity reading velocity.header.frame_id and performing
  a TF lookup at velocity.header.stamp
• The drop-on-TF-failure path in updateVelocity
• The zero-angular-on-TF-failure path in updateOrientation
  (added post-review)
• The same-frame short-circuit in updateOrientation
• Correct placement of rotated values into odom_.twist when the
  publish fires
• The interaction between updatePosition / updateOrientation /
  updateVelocity updates and the single odom_ publish

A regression in any of those paths would pass the current tests.

Proposed Scope

A new test target, e.g. test_mru_transform_integration, that:

1. Constructs a minimal rclcpp::Node fixture.
2. Populates a tf2_ros::Buffer with known static transforms
   (base_link → imu_link, base_link → velocity_frame).
3. Instantiates MRUTransform with deterministic params.
4. Uses NavigationSensors' callbacks directly — or
   call_callbacks_ equivalents — to feed synthetic position,
   orientation, and velocity messages.
5. Subscribes to /odom on a mock subscriber and asserts the
   published message's twist has the expected body-frame values.

Suggested cases:

Case	Setup	Expected
Velocity in world frame, IMU in base_link	TF map → base_link rotated 90° yaw, gps_vel pointing east	odom.twist.linear = north in body
Velocity with unknown frame	header.frame_id = "ghost_frame"	no publish, WARN_THROTTLE observed
IMU in sensor frame	TF base_link → imu_link rotated 180° roll, gyro = (0, 0, 1)	odom.twist.angular.z = -1
IMU with missing TF	no base_link → imu_link entry, gyro = (1, 2, 3)	odom.twist.angular = (0, 0, 0), WARN observed
Same-frame short-circuit	IMU header.frame_id = "base_link"	odom.twist.angular == input gyro, no TF lookup performed

Why not in PR #19

PR #19 was already +528 −6. Adding the rclcpp + tf fixture would
roughly double it and expand the review surface. The review-time
trade-off was to keep PR #19 focused on the fix + math coverage and
split integration coverage into a follow-up.

Related

• PR Rotate twist linear+angular+covariance into base_frame (REP-105) #19 (the fix this test would cover)
• Review discussion on PR Rotate twist linear+angular+covariance into base_frame (REP-105) #19, "Recommended Actions" item 5 option D

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Authored-By: Claude Code Agent
Model: Claude Opus 4.7 (1M context)