I Follow every step in the Ardupilot ROS2 setup documentation and i recieve this error .
Can i know where my mistake and Is this already the correct output ?
There are most likely some missing dependencies. Running the tests with a higher verbosity will provide more details, but I suspect you are missing launch-pytest and possibly socat:
sudo apt install socat ros-humble-launch-pytest
The missing test packages should not prevent you from running the AP_DDS UDP SITL example (last example in https://github.com/ArduPilot/ardupilot/tree/master/Tools/ros2#readme).
