Python - workaround for calling black formatter from tox (so success messages don't display in red)

tox.ini

# Problem:
# When you call the black formatter, it prints all output to standand
# error (even when no formatting is required). However, tox colors all
# output to standard error in bold red. This results in black's
# "All done! ... files left unchanged" message being colored red in
# console output (which is very annoying).
#
# Workaround:
# This is a `tox.ini` configuration file that invokes black through a
# Python subprocess and redirects output to standard output when
# successful so the output isn't displayed in red.
#
# see:
#   - black: https://black.readthedocs.io
#   - tox: https://tox.wiki

[testenv]
skip_install = true
deps = black
commands =
    {envpython} -c "import subprocess as s; import sys; "\
    "r = s.run(['black', '--check', '.'], capture_output=True, text=True, encoding='utf-8');"\
    "sys.stdout.write(r.stderr) if not r.returncode else sys.stderr.write(r.stderr)"