pep-723 metadata + pytest for a simple self-contained parameterized code example

demo.py

# /// script
# requires-python = ">=3.11"
# dependencies = [
#     "pytest",
# ]
# ///
import pytest
import sys
@pytest.mark.parametrize('msg', ['hello world\n', 'hello again\n'])
def test(msg: str):
  print(msg)

if __name__ == '__main__':
    sys.exit(pytest.main(['-s', __file__, f'-c {__file__}']))