Foxy already shows:
Warning: Passing ready_fn as an argument to generate_test_description
will be removed in a future release. Include a
launch_testing.actions.ReadyToTest action in the LaunchDescription instead.
* [#624 Mention that ready_fn in generate_test_description is deprecated (backport #623)](https://github.com/ros2/launch/pull/624) has been created for branch `foxy`
Foxy already shows: Warning: Passing ready_fn as an argument to generate_test_description will be removed in a future release. Include a launch_testing.actions.ReadyToTest action in the LaunchDescription instead.
see https://github.com/ros2/launch/pull/346
-> re-targeted version of https://github.com/ros2/launch/pull/580