True TOML config support

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

.pre-commit-config.yaml

@@ -24,7 +24,7 @@ repos:
     hooks:
       - id: pyproject-fmt
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: "v0.6.7"
+    rev: "v0.6.8"
     hooks:
       - id: ruff-format
       - id: ruff
@@ -39,12 +39,9 @@ repos:
     hooks:
       - id: rst-backticks
   - repo: https://github.com/rbubley/mirrors-prettier
-    rev: "v3.3.3" # Use the sha / tag you want to point at
+    rev: "v3.3.3"
     hooks:
       - id: prettier
-        additional_dependencies:
-          - prettier@3.3.3
-          - "@prettier/plugin-xml@3.4.1"
   - repo: local
     hooks:
       - id: changelogs-rst

docs/changelog/999.feature.rst

@@ -0,0 +1 @@
+Native TOML configuration support - by :user:`gaborbernat`.

pyproject.toml

@@ -53,19 +53,20 @@ dependencies = [
   "cachetools>=5.5",
   "chardet>=5.2",
   "colorama>=0.4.6",
-  "filelock>=3.15.4",
+  "filelock>=3.16.1",
   "packaging>=24.1",
-  "platformdirs>=4.2.2",
+  "platformdirs>=4.3.6",
   "pluggy>=1.5",
-  "pyproject-api>=1.7.1",
+  "pyproject-api>=1.8",
   "tomli>=2.0.1; python_version<'3.11'",
-  "virtualenv>=20.26.3",
+  "typing-extensions>=4.12.2; python_version<'3.11'",
+  "virtualenv>=20.26.6",
 ]
 optional-dependencies.docs = [
   "furo>=2024.8.6",
   "sphinx>=8.0.2",
-  "sphinx-argparse-cli>=1.17",
-  "sphinx-autodoc-typehints>=2.4",
+  "sphinx-argparse-cli>=1.18.2",
+  "sphinx-autodoc-typehints>=2.4.4",
   "sphinx-copybutton>=0.5.2",
   "sphinx-inline-tabs>=2023.4.21",
   "sphinxcontrib-towncrier>=0.2.1a0",
@@ -75,19 +76,19 @@ optional-dependencies.testing = [
   "build[virtualenv]>=1.2.2",
   "covdefaults>=2.3",
   "detect-test-pollution>=1.2",
-  "devpi-process>=1",
-  "diff-cover>=9.1.1",
+  "devpi-process>=1.0.2",
+  "diff-cover>=9.2",
   "distlib>=0.3.8",
   "flaky>=3.8.1",
   "hatch-vcs>=0.4",
   "hatchling>=1.25",
   "psutil>=6",
-  "pytest>=8.3.2",
+  "pytest>=8.3.3",
   "pytest-cov>=5",
   "pytest-mock>=3.14",
   "pytest-xdist>=3.6.1",
   "re-assert>=1.1",
-  "setuptools>=74.1.2",
+  "setuptools>=75.1",
   "time-machine>=2.15; implementation_name!='pypy'",
   "wheel>=0.44",
 ]

src/tox/config/loader/toml.py

@@ -0,0 +1,153 @@
+from __future__ import annotations
+
+import sys
+from inspect import isclass
+from pathlib import Path
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Dict,
+    Iterator,
+    List,
+    Literal,
+    Mapping,
+    Set,
+    TypeVar,
+    Union,
+    cast,
+)
+
+from tox.config.loader.api import Loader, Override
+from tox.config.types import Command, EnvList
+
+if TYPE_CHECKING:
+    from tox.config.loader.section import Section
+    from tox.config.main import Config
+
+if sys.version_info >= (3, 11):  # pragma: no cover (py311+)
+    from typing import TypeGuard
+else:  # pragma: no cover (py311+)
+    from typing_extensions import TypeGuard
+if sys.version_info >= (3, 10):  # pragma: no cover (py310+)
+    from typing import TypeAlias
+else:  # pragma: no cover (py310+)
+    from typing_extensions import TypeAlias
+
+TomlTypes: TypeAlias = Union[Dict[str, "TomlTypes"], List["TomlTypes"], str, int, float, bool, None]
+
+
+class TomlLoader(Loader[TomlTypes]):
+    """Load configuration from a pyproject.toml file."""
+
+    def __init__(
+        self,
+        section: Section,
+        overrides: list[Override],
+        content: Mapping[str, TomlTypes],
+        unused_exclude: set[str],
+    ) -> None:
+        self.content = content
+        self._unused_exclude = unused_exclude
+        super().__init__(section, overrides)
+
+    def __repr__(self) -> str:
+        return f"{self.__class__.__name__}({self.section.name}, {self.content!r})"
+
+    def load_raw(self, key: str, conf: Config | None, env_name: str | None) -> TomlTypes:  # noqa: ARG002
+        return self.content[key]
+
+    def found_keys(self) -> set[str]:
+        return set(self.content.keys()) - self._unused_exclude
+
+    @staticmethod
+    def to_str(value: TomlTypes) -> str:
+        return _ensure_type_correct(value, str)  # type: ignore[return-value] # no mypy support
+
+    @staticmethod
+    def to_bool(value: TomlTypes) -> bool:
+        return _ensure_type_correct(value, bool)
+
+    @staticmethod
+    def to_list(value: TomlTypes, of_type: type[Any]) -> Iterator[_T]:
+        of = List[of_type]  # type: ignore[valid-type] # no mypy support
+        return iter(_ensure_type_correct(value, of))  # type: ignore[call-overload,no-any-return]
+
+    @staticmethod
+    def to_set(value: TomlTypes, of_type: type[Any]) -> Iterator[_T]:
+        of = Set[of_type]  # type: ignore[valid-type] # no mypy support
+        return iter(_ensure_type_correct(value, of))  # type: ignore[call-overload,no-any-return]
+
+    @staticmethod
+    def to_dict(value: TomlTypes, of_type: tuple[type[Any], type[Any]]) -> Iterator[tuple[_T, _T]]:
+        of = Dict[of_type[0], of_type[1]]  # type: ignore[valid-type] # no mypy support
+        return _ensure_type_correct(value, of).items()  # type: ignore[attr-defined,no-any-return]
+
+    @staticmethod
+    def to_path(value: TomlTypes) -> Path:
+        return Path(TomlLoader.to_str(value))
+
+    @staticmethod
+    def to_command(value: TomlTypes) -> Command:
+        return Command(args=cast(List[str], value))  # validated during load in _ensure_type_correct
+
+    @staticmethod
+    def to_env_list(value: TomlTypes) -> EnvList:
+        return EnvList(envs=list(TomlLoader.to_list(value, str)))
+
+
+_T = TypeVar("_T")
+
+
+def _ensure_type_correct(val: TomlTypes, of_type: type[_T]) -> TypeGuard[_T]:  # noqa: C901, PLR0912
+    casting_to = getattr(of_type, "__origin__", of_type.__class__)
+    msg = ""
+    if casting_to in {list, List}:
+        entry_type = of_type.__args__[0]  # type: ignore[attr-defined]
+        if isinstance(val, list):
+            for va in val:
+                _ensure_type_correct(va, entry_type)
+        else:
+            msg = f"{val!r} is not list"
+    elif isclass(of_type) and issubclass(of_type, Command):
+        # first we cast it to list then create commands, so for now just validate is a nested list
+        _ensure_type_correct(val, List[str])
+    elif casting_to in {set, Set}:
+        entry_type = of_type.__args__[0]  # type: ignore[attr-defined]
+        if isinstance(val, set):
+            for va in val:
+                _ensure_type_correct(va, entry_type)
+        else:
+            msg = f"{val!r} is not set"
+    elif casting_to in {dict, Dict}:
+        key_type, value_type = of_type.__args__[0], of_type.__args__[1]  # type: ignore[attr-defined]
+        if isinstance(val, dict):
+            for va in val:
+                _ensure_type_correct(va, key_type)
+            for va in val.values():
+                _ensure_type_correct(va, value_type)
+        else:
+            msg = f"{val!r} is not dictionary"
+    elif casting_to == Union:  # handle Optional values
+        args: list[type[Any]] = of_type.__args__  # type: ignore[attr-defined]
+        for arg in args:
+            try:
+                _ensure_type_correct(val, arg)
+                break
+            except TypeError:
+                pass
+        else:
+            msg = f"{val!r} is not union of {', '.join(a.__name__ for a in args)}"
+    elif casting_to in {Literal, type(Literal)}:
+        choice = of_type.__args__  # type: ignore[attr-defined]
+        if val not in choice:
+            msg = f"{val!r} is not one of literal {','.join(repr(i) for i in choice)}"
+    elif not isinstance(val, of_type):
+        msg = f"{val!r} is not of type {of_type.__name__!r}"
+    if msg:
+        raise TypeError(msg)
+    return cast(_T, val)  # type: ignore[return-value] # logic too complicated for mypy
+
+
+__all__ = [
+    "TomlLoader",
+]

src/tox/config/source/api.py

@@ -23,6 +23,9 @@ def __init__(self, path: Path) -> None:
         self.path: Path = path  #: the path to the configuration source
         self._section_to_loaders: dict[str, list[Loader[Any]]] = {}
 
+    def __repr__(self) -> str:
+        return f"{self.__class__.__name__}(path={self.path})"
+
     def get_loaders(
         self,
         section: Section,

src/tox/config/source/discover.py

@@ -9,12 +9,20 @@
 
 from .legacy_toml import LegacyToml
 from .setup_cfg import SetupCfg
+from .toml_pyproject import TomlPyProject
+from .toml_tox import TomlTox
 from .tox_ini import ToxIni
 
 if TYPE_CHECKING:
     from .api import Source
 
-SOURCE_TYPES: tuple[type[Source], ...] = (ToxIni, SetupCfg, LegacyToml)
+SOURCE_TYPES: tuple[type[Source], ...] = (
+    ToxIni,
+    SetupCfg,
+    LegacyToml,
+    TomlPyProject,
+    TomlTox,
+)
 
 
 def discover_source(config_file: Path | None, root_dir: Path | None) -> Source:
@@ -79,7 +87,8 @@ def _create_default_source(root_dir: Path | None) -> Source:
                 break
     else:  # if not set use where we find pyproject.toml in the tree or cwd
         empty = root_dir
-    logging.warning("No %s found, assuming empty tox.ini at %s", " or ".join(i.FILENAME for i in SOURCE_TYPES), empty)
+    names = " or ".join({i.FILENAME: None for i in SOURCE_TYPES})
+    logging.warning("No %s found, assuming empty tox.ini at %s", names, empty)
     return ToxIni(empty / "tox.ini", content="")
 
 

src/tox/config/source/ini.py

@@ -107,9 +107,6 @@ def _discover_from_section(self, section: IniSection, known_factors: set[str]) -
                 if set(env.split("-")) - known_factors:
                     yield env
 
-    def __repr__(self) -> str:
-        return f"{type(self).__name__}(path={self.path})"
-
 
 __all__ = [
     "IniSource",