Compile error while building `tf2_kdl` with `BUILD_TESTING` on - windows 10

Bug report

Required Info:

• Operating System:
  • Windows 10
• Installation type:
  • source, with BUILD_TESTING
• Version or commit hash:
  • ae2120833d1777eaa91a3fa4943d56b675db3e52 (humble branch)
• DDS implementation:
  • fastrtps
• Client library (if applicable):
  • N/A

Steps to reproduce issue

Build geometry2 package with BUILD_TESTING on.

colcon build --cmake-args -DBUILD_TESTING:int=1

Expected behavior

Build succeeded

Actual behavior

Compile error for tf2_kdl package:

D:\ros2-humble\include\orocos_kdl\kdl\jacobian.hpp(26,10): fatal error C1083: cannot open include file 'Eigen/Core' no such file or directory

Additional information

Looks like Eigen is not added to include dirs. Adding it fixes the issue:

if(BUILD_TESTING)
  find_package(ament_cmake_gtest REQUIRED)
  find_package(rclcpp REQUIRED)
  find_package(tf2_msgs REQUIRED)
  find_package(Eigen3 REQUIRED)

  ament_add_gtest(test_kdl test/test_tf2_kdl.cpp)
  target_include_directories(
    test_kdl PRIVATE
    "${Eigen3_INCLUDE_DIRS}"
  )
  target_link_libraries(test_kdl
    tf2_kdl
    rclcpp::rclcpp
    # Used, but not linked to test tf2_kdl's exports:
    #   tf2::tf2
    #   tf2_ros::tf2_ros
  )
endif()

Reproduce the failure with colcon build --cmake-args -DBUILD_TESTING:int=1 and inspect the tf2_kdl test target using test/test_tf2_kdl.cpp. Check how the target receives Eigen's include path, then verify that the package builds successfully with testing enabled on Windows.