Error with requires when using native TOML configuration

[daneah]

Issue

tox doesn't like the requires key when using (as documented) native TOML configuration.

Environment

Provide at least:

• OS: macOS

Output of pip list of the host Python, where tox is installed

$ pipx runpip tox list
Package       Version
------------- -------
cachetools    5.5.0
chardet       5.2.0
colorama      0.4.6
distlib       0.3.7
filelock      3.16.1
packaging     24.1
pip           24.2
platformdirs  4.3.6
pluggy        1.5.0
pyproject-api 1.8.0
setuptools    69.0.2
tox           4.21.0
tox-uv        1.13.0
uv            0.4.18
virtualenv    20.26.6
wheel         0.42.0

Output of running tox

Output of tox -rvv

Traceback (most recent call last):
  File "/Users/dhillard/.local/bin/tox", line 8, in <module>
    sys.exit(run())
             ^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/run.py", line 20, in run
    result = main(sys.argv[1:] if args is None else args)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/run.py", line 42, in main
    result = provision(state)
             ^^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/provision.py", line 89, in provision
    requires: list[Requirement] = state.conf.core["requires"]
                                  ~~~~~~~~~~~~~~~^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/sets.py", line 116, in __getitem__
    return self.load(item)
           ^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/sets.py", line 127, in load
    return config_definition.__call__(self._conf, self.loaders, ConfigLoadArgs(chain, self.name, self.env_name))  # noqa: PLC2801
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/of_type.py", line 109, in __call__
    value = loader.load(key, self.of_type, self.factory, conf, args)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/loader/api.py", line 148, in load
    converted = self.build(key, of_type, factory, conf, raw, args)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/loader/toml/__init__.py", line 66, in build
    return self.to(exploded, of_type, factory)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/loader/convert.py", line 33, in to
    return self._to_typing(raw, of_type, factory)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/loader/convert.py", line 60, in _to_typing
    result = [self.to(i, entry_type, factory) for i in self.to_list(raw, entry_type)]
                                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/loader/toml/__init__.py", line 82, in to_list
    return iter(validate(value, of))  # type: ignore[call-overload,no-any-return]
                ^^^^^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/loader/toml/_validate.py", line 37, in validate
    validate(va, entry_type)
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/loader/toml/_validate.py", line 69, in validate
    raise TypeError(msg)
TypeError: 'tox>=4.21.0' is not of type 'Requirement'

Minimal example

$ ls -a
.    ..    pyproject.toml

# pyproject.toml

[tool.tox]
requires = ["tox>=4.21.0"]

$ tox --version
4.21.0 from /Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/__init__.py
registered plugins:
    tox-uv-1.13.0 at /Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox_uv/plugin.py with uv==0.4.18

[gaborbernat]

This now has been fixed in 4.21.1.