build works

python -m build

.gitignore

@@ -22,3 +22,5 @@ src/icalendar.egg-info/
 !.gitignore
 venv
 /ical_fuzzer.pkg.spec
+/src/icalendar/_version.py
+

pyproject.toml

@@ -0,0 +1,198 @@
+#
+# We use the pyproject.toml package specification.
+# See https://packaging.python.org/en/latest/guides/section-build-and-publish/
+# See https://github.com/collective/icalendar/issues/686
+# See https://packaging.python.org/en/latest/specifications/pyproject-toml/#license
+#
+
+# TODO:
+# - plone developers email still in use for this?
+# - setup.cfg
+# - tox test dependencies
+# - In the readme, link to these:
+#     "CONTRIBUTING.rst",
+#     "CHANGES.rst",
+#     "LICENSE.rst"
+# - from setup.py:
+#   - license='BSD-2-Clause',
+#   - packages=setuptools.find_namespace_packages('src', exclude=["icalendar.fuzzing"]),
+#   - package_dir={'': 'src'},
+#   - include_package_data=True,
+#   - zip_safe=False
+#   - test_suite='icalendar.tests'
+# DONE:
+# - ruff in tox
+# - version.py
+#   - long_description_content_type="text/x-rst",
+
+
+[build-system]
+requires = ["hatchling", "hatch-vcs"]
+build-backend = "hatchling.build"
+
+[project]
+name = "icalendar"
+license = { file = "LICENSE.rst", name = "BSD-2-Clause" }
+#    name = "BSD-2-Clause", # TODO: is this the right short key
+keywords = [
+    "calendar",
+    "calendaring",
+    "ical",
+    "icalendar",
+    "event",
+    "todo",
+    "journal",
+    "recurring",
+]
+authors = [
+  { name="Plone Foundation", email="plone-developers@lists.sourceforge.net" },
+]
+maintainers = [
+  { name="Nicco Kunzmann", email="niccokunzmann@rambler.ru" },
+  { name="Christian Geier" },
+  { name="Jaca", email="vitouejj@gmail.com" },
+]
+# These attributes are dynamically generated by hatch-vcs
+dynamic = [
+    "urls",
+    "version"
+]
+description = "iCalendar parser/generator"
+readme = { file = "README.rst", content-type = "text/x-rst" }
+
+#
+# When adjusting the Python Version, adjust also:
+# - .github/workflows/tests.yml
+# - the classifiers below
+# - the documentation
+# - the README file
+# - dependencies for 3.8, Python 3.13 will come our October, too
+# - tool.ruff.target-version
+#
+requires-python = ">=3.8"
+
+# see https://pypi.python.org/pypi?%3Aaction=list_classifiers
+classifiers = [
+    "Development Status :: 3 - Alpha",
+    "Intended Audience :: Developers",
+    "License :: OSI Approved :: BSD License",
+    "Operating System :: OS Independent",
+    "Programming Language :: Python",
+    "Programming Language :: Python :: 3.8",
+    "Programming Language :: Python :: 3.9",
+    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: Implementation :: CPython",
+    "Programming Language :: Python :: Implementation :: PyPy",
+]
+
+dependencies = [
+    "python-dateutil",
+    # install requirements depending on python version, TODO: Remove with Python 3.8
+    # see https://www.python.org/dev/peps/pep-0508/#environment-markers
+    "backports.zoneinfo; python_version < '3.9'",
+    "tzdata"
+]
+
+[project.optional-dependencies]
+test = [
+    "pytest",
+    "coverage",
+    "hypothesis",
+    "pytz",
+]
+
+[project.scripts]
+icalendar = "icalendar.cli:main"
+
+[tool.hatch.metadata.hooks.vcs.urls]
+# This is a dynamic generation of [project.urls]
+Homepage = "https://icalendar.readthedocs.io/"
+Repository = "https://github.com/collective/icalendar/"
+source_archive = "https://github.com/collective/icalendar/archive/{commit_hash}.zip"
+Issues = "https://github.com/collective/icalendar/issues"
+Documentation = "https://icalendar.readthedocs.io/"
+Changelog = "https://icalendar.readthedocs.io/en/latest/changelog.html"
+
+[tool.hatch.version]
+# This configuration allows us to use the version from the tags and dynamically generate
+# version files. This speeds up the release process.
+source = "vcs"
+
+[tool.hatch.version.raw-options]
+# see https://github.com/ofek/hatch-vcs/issues/43#issuecomment-1553065222
+local_scheme = "no-local-version"
+
+[tool.hatch.build.hooks.vcs]
+version-file = "src/icalendar/_version.py"
+
+[tool.hatch.metadata]
+allow-direct-references = true
+
+[tool.ruff]
+target-version = "py38"
+
+[tool.ruff.lint]
+select = ["ALL"]
+ignore = [
+    "ANN",     # flake8-annotations
+    "B020",    # Loop control variable {name} overrides iterable it iterates
+    "C401",    # Unnecessary generator (rewrite as a set comprehension)
+    "C901",    # {name} is too complex ({complexity} > {max_complexity})
+    "COM812",  # Trailing comma missing
+    "D1",      # Missing docstring
+    "D2",      # docstrings stuffs
+    "D4",      # docstrings stuffs
+    "EM10",    # Exception string usage
+    "ERA001",  # Found commented-out code
+    "FBT002",  # Boolean default positional argument in function definition
+    "FIX",     # TODO comments
+    "ISC001",  # Implicitly concatenated string literals on one line (to avoid with formatter)
+    "N818",    # Exception name {name} should be named with an Error suffix
+    "PLR091",  # Too many things (complexity, arguments, branches, etc...)
+    "PLR2004", # Magic value used in comparison, consider replacing {value} with a constant variable
+    "RUF012",  # Mutable class attributes should be annotated with typing.ClassVar
+    "RUF015",  # Prefer next({iterable}) over single element slice
+    "S101",    # Use of assert detected
+    "TD",      # TODO comments
+    "TRY003",  # Avoid specifying long messages outside the exception class
+    "S104",    # Possible binding to all interfaces
+    "E722",    # Do not use bare `except`
+    "RUF005",  # Consider iterable unpacking instead of concatenation
+    "DTZ005",  # `datetime.datetime.now()` called without a `tz` argument
+    "PERF401", # Use a list comprehension to create a transformed list
+    "ARG002",  # Unused method argument: ...
+    "ARG001",  # Unused function argument: ...
+]
+extend-safe-fixes = [
+    "PT006", # Wrong type passed to first argument of @pytest.mark.parametrize; expected {expected_string}
+]
+
+[tool.ruff.lint.per-file-ignores]
+"src/icalendar/tests/*" = [
+    "B011",   # Do not assert False (python -O removes these calls), raise AssertionError()
+    "DTZ001", # datetime.datetime() called without a tzinfo argument
+    "E501",   # Indentation is not a multiple of {indent_size}
+    "N802",   # Function name {name} should be lowercase
+    "PT011",  # pytest.raises({exception}) is too broad, set the match parameter or use a more specific exception
+    "PT012",  # pytest.raises() block should contain a single simple statement
+    "PT015",  # Assertion always fails, replace with pytest.fail()
+    "T201",   # print found
+    "T203",   # `pprint` found
+    "RUF001", # String contains ambiguous character
+]
+
+[tool.pytest.ini_options]
+# see https://docs.pytest.org/en/6.2.x/customize.html
+minversion = "6.0"
+# see https://docs.pytest.org/en/6.2.x/reference.html?highlight=testpaths#confval-testpaths
+testpaths = [
+    "src/icalendar/tests",
+]
+# see https://docs.pytest.org/en/6.2.x/reference.html?highlight=testpaths#confval-norecursedirs
+norecursedirs = [
+    "src/icalendar/tests/hypothesis",
+    "build",
+]
+

src/icalendar/version.py

@@ -0,0 +1,13 @@
+"""Version file as a stable interface for the generated _version.py file."""
+try:
+    from ._version import __version__, __version_tuple__, version, version_tuple
+except ModuleNotFoundError:
+    __version__ = version = "0.0.0dev0"
+    __version_tuple__ = version_tuple = (0, 0, 0, "dev0")
+
+__all__ = [
+    "__version__",
+    "version",
+    "__version_tuple__",
+    "version_tuple",
+]

tox.ini

@@ -8,10 +8,7 @@ envlist = py38,py39,py310,py311,312,pypy3,docs,nopytz
 [testenv]
 usedevelop=True
 deps =
-    pytest
-    coverage
-    hypothesis
-    pytz
+    -e .[test]
 commands =
     coverage run --branch --source=src/icalendar --omit=*/tests/hypothesis/* --omit=*/tests/fuzzed/* --module pytest []
     coverage report
@@ -45,3 +42,11 @@ changedir = docs
 allowlist_externals = make
 commands =
     make html
+
+[testenv:ruff]
+# use tox -e ruff to format the code base
+deps = ruff
+skip_install = True
+commands =
+    ruff format
+    ruff check --fix