colcon test failed in python package

edit

i want do create some tests for my ROS packages. So i started with an example package to begin. I've created a python package with following command:

ros2 pkg create --build-type ament_python --maintainer-name "test user" --maintainer-email test@user.com --license "Apache License 2.0" --description "This is a simple test example" test_package

then I build the package with colcon:

colcon build --packages-select test_package && source install/setup.zsh

I startet the test cases over the colcon test command for my package with:

colcon test --packages-select test_package

As output i get:

Starting >>> test_package
--- stderr: test_package                   

=============================== warnings summary ===============================
/usr/lib/python3/dist-packages/pydocstyle/config.py:6
  Warning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated since Python 3.3, and in 3.9 it will stop working


-- Docs: https://docs.pytest.org/en/latest/warnings.html
---
Finished <<< test_package [1.07s]

Summary: 1 package finished [1.28s]
  1 package had stderr output: test_package

Why are the standard test fails? Did i do something wrong? I thought it would still work for a few weeks without any warnings I'm working on Foxy and Ubuntu 20.04