Add 3.14 support and drop 3.9

Signed-off-by: Bernát Gábor <bgabor8@bloomberg.net>

Author: gaborbernat

.github/workflows/check.yaml

@@ -28,7 +28,6 @@ jobs:
           - "3.12"
           - "3.11"
           - "3.10"
-          - "3.9"
         os:
           - ubuntu-24.04
           - windows-2025
@@ -66,6 +65,7 @@ jobs:
       matrix:
         tox_env:
           - type
+          - type-3.10
           - dev
           - docs
           - pkg_meta
@@ -89,7 +89,10 @@ jobs:
         shell: bash
         run: echo "$USERPROFILE/.local/bin" >> $GITHUB_PATH
       - name: Install tox@self
-        run: uv tool install --python-preference only-managed --python 3.13 tox@.
+        run: uv tool install --python-preference only-managed --python 3.14 tox@.
+      - name: Install Python 3.10 for type-3.10
+        if: matrix.tox_env == 'type-3.10'
+        run: uv python install 3.10
       - name: Setup check suite
         run: tox r -vv --notest --skip-missing-interpreters false -e ${{ matrix.tox_env }}
       - name: Run check for ${{ matrix.tox_env }}

.github/workflows/release.yaml

@@ -21,7 +21,7 @@ jobs:
           cache-dependency-glob: "pyproject.toml"
           github-token: ${{ secrets.GITHUB_TOKEN }}
       - name: Build package
-        run: uv build --python 3.13 --python-preference only-managed --sdist --wheel . --out-dir dist
+        run: uv build --python 3.14 --python-preference only-managed --sdist --wheel . --out-dir dist
       - name: Store the distribution packages
         uses: actions/upload-artifact@v4
         with:

.pre-commit-config.yaml

@@ -13,17 +13,17 @@ repos:
     rev: v2.4.1
     hooks:
       - id: codespell
-        additional_dependencies: ["tomli>=2.2.1"]
+        additional_dependencies: ["tomli>=2.3"]
   - repo: https://github.com/tox-dev/pyproject-fmt
-    rev: "v2.6.0"
+    rev: "v2.8.0"
     hooks:
       - id: pyproject-fmt
   - repo: https://github.com/abravalheri/validate-pyproject
     rev: "v0.24.1"
     hooks:
       - id: validate-pyproject
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: "v0.13.2"
+    rev: "v0.14.0"
     hooks:
       - id: ruff-check
         args: ["--fix", "--unsafe-fixes", "--exit-non-zero-on-fix"]
@@ -32,7 +32,7 @@ repos:
     rev: 1.20.0
     hooks:
       - id: blacken-docs
-        additional_dependencies: [black==25.1]
+        additional_dependencies: [black==25.9]
   - repo: https://github.com/pre-commit/pygrep-hooks
     rev: v1.10.0
     hooks:

.readthedocs.yaml

@@ -5,6 +5,7 @@ build:
     python: "3"
   commands:
     - pip install uv
-    - uv venv
+    - uv venv -p 3.14
     - uv pip install tox-uv tox@.
-    - .venv/bin/tox run -e docs --
+    - .venv/bin/tox run -e docs --notest
+    - .venv/bin/tox run -e docs --skip-pkg-install --

docs/installation.rst

@@ -4,7 +4,7 @@ Installation
 As tool
 -------
 
-:pypi:`tox` is a CLI tool that needs a Python interpreter (version 3.9 or higher) to run. We recommend either
+:pypi:`tox` is a CLI tool that needs a Python interpreter (version 3.10 or higher) to run. We recommend either
 :pypi:`pipx` or :pypi:`uv` to install tox into an isolated environment. This has the added benefit that later you'll
 be able to upgrade tox without affecting other parts of the system. We provide method for ``pip`` too here but we
 discourage that path if you can:
@@ -80,7 +80,7 @@ Python and OS Compatibility
 
 tox works with the following Python interpreter implementations:
 
-- `CPython <https://www.python.org/>`_ versions 3.9, 3.10, 3.11, 3.12, 3.13
+- `CPython <https://www.python.org/>`_ versions 3.10, 3.11, 3.12, 3.13, 3.14
 
 This means tox works on the latest patch version of each of these minor versions. Previous patch versions are supported
 on a best effort approach.

pyproject.toml

@@ -26,7 +26,7 @@ maintainers = [
 authors = [
   { name = "Bernát Gábor", email = "gaborjbernat@gmail.com" },
 ]
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 classifiers = [
   "Development Status :: 5 - Production/Stable",
   "Framework :: tox",
@@ -36,7 +36,6 @@ classifiers = [
   "Operating System :: Microsoft :: Windows",
   "Operating System :: POSIX",
   "Programming Language :: Python :: 3 :: Only",
-  "Programming Language :: Python :: 3.9",
   "Programming Language :: Python :: 3.10",
   "Programming Language :: Python :: 3.11",
   "Programming Language :: Python :: 3.12",
@@ -50,17 +49,17 @@ dynamic = [
   "version",
 ]
 dependencies = [
-  "cachetools>=6.1",
+  "cachetools>=6.2",
   "chardet>=5.2",
   "colorama>=0.4.6",
-  "filelock>=3.18",
+  "filelock>=3.19.1",
   "packaging>=25",
-  "platformdirs>=4.3.8",
+  "platformdirs>=4.5",
   "pluggy>=1.6",
   "pyproject-api>=1.9.1",
-  "tomli>=2.2.1; python_version<'3.11'",
-  "typing-extensions>=4.14.1; python_version<'3.11'",
-  "virtualenv>=20.31.2",
+  "tomli>=2.3; python_version<'3.11'",
+  "typing-extensions>=4.15; python_version<'3.11'",
+  "virtualenv>=20.34",
 ]
 urls.Documentation = "https://tox.wiki"
 urls.Homepage = "http://tox.readthedocs.org"
@@ -76,55 +75,55 @@ dev = [
   { include-group = "type" },
 ]
 test = [
-  "build[virtualenv]>=1.2.2.post1",
+  "build[virtualenv]>=1.3",
   "covdefaults>=2.3",
-  "coverage>=7.9.2",
+  "coverage>=7.10.7",
   "detect-test-pollution>=1.2",
   "devpi-process>=1.0.2",
-  "diff-cover>=9.6",
+  "diff-cover>=9.7.1",
   "distlib>=0.4",
   "flaky>=3.8.1",
   "hatch-vcs>=0.5",
   "hatchling>=1.27",
-  "pdm-backend",
-  "psutil>=7",
-  "pytest>=8.4.1",
-  "pytest-cov>=6.2.1",
-  "pytest-mock>=3.14.1",
+  "pdm-backend>=2.4.5",
+  "psutil>=7.1",
+  "pytest>=8.4.2",
+  "pytest-cov>=7",
+  "pytest-mock>=3.15.1",
   "pytest-xdist>=3.8",
   "re-assert>=1.1",
   "setuptools>=80.9",
-  "time-machine>=2.16; implementation_name!='pypy'",
+  "time-machine>=2.19; implementation_name!='pypy'",
   "wheel>=0.45.1",
 ]
 type = [
-  "mypy==1.17",
-  "types-cachetools>=6.1.0.20250717",
+  "mypy==1.18.2",
+  "types-cachetools>=6.2.0.20250827",
   "types-chardet>=5.0.4.6",
   { include-group = "test" },
 ]
 docs = [
-  "furo>=2025.7.19",
+  "furo>=2025.9.25",
   "sphinx>=8.2.3",
-  "sphinx-argparse-cli>=1.19",
-  "sphinx-autodoc-typehints>=3.2",
+  "sphinx-argparse-cli>=1.20.1",
+  "sphinx-autodoc-typehints>=3.4",
   "sphinx-copybutton>=0.5.2",
   "sphinx-inline-tabs>=2023.4.21",
   "sphinxcontrib-towncrier>=0.2.1a0",
-  "towncrier>=24.8",
+  "towncrier>=25.8",
 ]
 fix = [
-  "pre-commit-uv>=4.1.4",
+  "pre-commit-uv>=4.1.5",
 ]
 pkg-meta = [
-  "check-wheel-contents>=0.6.2",
-  "twine>=6.1",
-  "uv>=0.8",
+  "check-wheel-contents>=0.6.3",
+  "twine>=6.2",
+  "uv>=0.9",
 ]
 release = [
-  "gitpython>=3.1.44",
+  "gitpython>=3.1.45",
   "packaging>=25",
-  "towncrier>=24.8",
+  "towncrier>=25.8",
 ]
 
 [tool.hatch]
@@ -140,7 +139,6 @@ build.targets.sdist.include = [
 version.source = "vcs"
 
 [tool.ruff]
-target-version = "py38"
 line-length = 120
 format.preview = true
 format.docstring-code-line-length = 100
@@ -238,7 +236,6 @@ template = "docs/changelog/template.jinja2"
 # possible types, all default: feature, bugfix, doc, removal, misc
 
 [tool.mypy]
-python_version = "3.11"
 show_error_codes = true
 strict = true
 overrides = [

src/tox/config/cli/env_var.py

@@ -4,7 +4,7 @@
 
 import logging
 import os
-from typing import Any, List
+from typing import Any
 
 from tox.config.loader.str_convert import StrConvert
 
@@ -25,7 +25,7 @@ def get_env_var(key: str, of_type: type[Any]) -> tuple[Any, str] | None:
             value = os.environ[environ_key]
             origin = getattr(of_type, "__origin__", of_type.__class__)
             try:
-                if origin in {list, List}:
+                if origin in {list, list}:
                     entry_type = of_type.__args__[0]
                     result = [CONVERT.to(raw=v, of_type=entry_type, factory=None) for v in value.split(";")]
                 else:

src/tox/config/cli/parse.py

@@ -6,14 +6,16 @@
 import os
 from contextlib import redirect_stderr
 from pathlib import Path
-from typing import TYPE_CHECKING, Callable, NamedTuple, Sequence, cast
+from typing import TYPE_CHECKING, NamedTuple, cast
 
 from tox.config.source import Source, discover_source
 from tox.report import ToxHandler, setup_report
 
 from .parser import Parsed, ToxParser
 
 if TYPE_CHECKING:
+    from collections.abc import Callable, Sequence
+
     from tox.session.state import State
 
 
@@ -47,9 +49,10 @@ def _get_base(args: Sequence[str]) -> tuple[int, ToxHandler, Source]:
     tox_parser = ToxParser.base()
     parsed = Parsed()
     try:
-        with Path(os.devnull).open(
-            "w", encoding=locale.getpreferredencoding(do_setlocale=False)
-        ) as file_handler, redirect_stderr(file_handler):
+        with (
+            Path(os.devnull).open("w", encoding=locale.getpreferredencoding(do_setlocale=False)) as file_handler,
+            redirect_stderr(file_handler),
+        ):
             tox_parser.parse_known_args(args, namespace=parsed)
     except SystemExit:
         ...  # ignore parse errors, such as -va raises ignored explicit argument 'a'

src/tox/config/cli/parser.py

@@ -9,7 +9,8 @@
 import sys
 from argparse import SUPPRESS, Action, ArgumentDefaultsHelpFormatter, ArgumentError, ArgumentParser, Namespace
 from pathlib import Path
-from typing import TYPE_CHECKING, Any, Callable, Dict, List, Literal, Optional, Sequence, Tuple, Type, TypeVar, cast
+from types import UnionType
+from typing import TYPE_CHECKING, Any, Literal, TypeVar, cast
 
 from colorama import Fore
 
@@ -26,6 +27,8 @@
     from typing_extensions import Self
 
 if TYPE_CHECKING:
+    from collections.abc import Callable, Sequence
+
     from tox.session.state import State
 
 
@@ -64,7 +67,7 @@ def get_type(action: Action) -> type[Any]:
         of_type: type[Any] | None = getattr(action, "of_type", None)
         if of_type is None:
             if isinstance(action, argparse._AppendAction):  # noqa: SLF001
-                of_type = List[action.type]  # type: ignore[name-defined]
+                of_type = list[action.type]  # type: ignore[name-defined]
             elif isinstance(action, argparse._StoreAction) and action.choices:  # noqa: SLF001
                 loc = locals()
                 loc["Literal"] = Literal
@@ -135,7 +138,7 @@ def is_colored(self) -> bool:
     exit_and_dump_after: int
 
 
-ArgumentArgs = Tuple[Tuple[str, ...], Optional[Type[Any]], Dict[str, Any]]
+ArgumentArgs = tuple[tuple[str, ...], type[Any] | UnionType | None, dict[str, Any]]
 
 
 class ToxParser(ArgumentParserWithEnvAndConfig):
@@ -230,7 +233,7 @@ def __call__(
             help="set PYTHONHASHSEED to SEED before running commands. Defaults to a random integer in the range "
             "[1, 4294967295] ([1, 1024] on Windows). Passing 'notset' suppresses this behavior.",
             action=SeedAction,
-            of_type=Optional[int],  # type: ignore[arg-type]
+            of_type=int | None,
             default=hashseed_default,
             dest="hash_seed",
         )
@@ -239,7 +242,7 @@ def __call__(
             dest="discover",
             nargs="+",
             metavar="path",
-            of_type=List[str],
+            of_type=list[str],
             help="for Python discovery first try these Python executables",
             default=[],
         )
@@ -280,7 +283,7 @@ def add_argument(*a_args: str, of_type: type[Any] | None = None, **a_kwargs: Any
             self._groups.append((args, kwargs, excl))
         return result
 
-    def add_argument(self, *args: str, of_type: type[Any] | None = None, **kwargs: Any) -> Action:
+    def add_argument(self, *args: str, of_type: type[Any] | UnionType | None = None, **kwargs: Any) -> Action:
         result = super().add_argument(*args, **kwargs)
         if self.of_cmd is None and result.dest != "help":
             self._arguments.append((args, of_type, kwargs))
@@ -403,7 +406,7 @@ def add_core_arguments(parser: ArgumentParser) -> None:
         metavar="file",
         default=None,
         type=Path,
-        of_type=Optional[Path],
+        of_type=Path | None,
         help="configuration file/folder for tox (if not specified will discover one)",
     )
     parser.add_argument(
@@ -412,7 +415,7 @@ def add_core_arguments(parser: ArgumentParser) -> None:
         metavar="dir",
         default=None,
         type=Path,
-        of_type=Optional[Path],
+        of_type=Path | None,
         help="tox working directory (if not specified will be the folder of the config file)",
     )
     parser.add_argument(
@@ -421,7 +424,7 @@ def add_core_arguments(parser: ArgumentParser) -> None:
         metavar="dir",
         default=None,
         type=Path,
-        of_type=Optional[Path],
+        of_type=Path | None,
         help="project root directory (if not specified will be the folder of the config file)",
     )