Unable to modify PATH environment variable by setenv

[fonlan]

Issue

When try to append path to PATH environment variable via setenv section in tox.ini, it will not take effect.

setenv = 
    PATH = {env:PATH}:/test
commands = 
    env

As above tox.ini example, I can't find append /test in command env output.

Environment

• OS: Ubuntu 22.04.3 LTS
• Python: 3.10.12

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

Package           Version
----------------- -------
cachetools        5.5.0
chardet           5.2.0
colorama          0.4.6
distlib           0.3.9
filelock          3.16.1
packaging         24.2
pip               22.0.2
platformdirs      4.3.6
pluggy            1.5.0
pyproject-api     1.8.0
setuptools        59.6.0
tomli             2.1.0
tox               4.23.2
typing_extensions 4.12.2
virtualenv        20.27.1

Output of running tox

Output of tox -rvv

❯ python3 -m tox run -rvv -e test 
test: 201 W remove tox env folder /home/username/.tox/test [tox/tox_env/api.py:325]
test: 238 I find interpreter for spec PythonSpec(path=/home/username/.venv/bin/python3) [virtualenv/discovery/builtin.py:73]
test: 239 D filesystem is case-sensitive [virtualenv/info.py:25]
test: 239 D discover exe for PythonInfo(spec=CPython3.10.12.final.0-64, exe=/home/username/.venv/bin/python3, platform=linux, version='3.10.12 (main, Sep 11 2024, 15:47:36) [GCC 11.4.0]', encoding_fs_io=utf-8-utf-8) in /usr [virtualenv/discovery/py_info.py:437]
test: 240 D got python info of %s from (PosixPath('/usr/bin/python3.10'), PosixPath('/home/username/.local/share/virtualenv/py_info/1/8a94588eda9d64d9e9a351ab8144e55b1fabf5113b54e67dd26a8c27df0381b3.json')) [virtualenv/app_data/via_disk_folder.py:131]
test: 241 I proposed PythonInfo(spec=CPython3.10.12.final.0-64, system=/usr/bin/python3.10, exe=/home/username/.venv/bin/python3, platform=linux, version='3.10.12 (main, Sep 11 2024, 15:47:36) [GCC 11.4.0]', encoding_fs_io=utf-8-utf-8) [virtualenv/discovery/builtin.py:80]
test: 241 D accepted PythonInfo(spec=CPython3.10.12.final.0-64, system=/usr/bin/python3.10, exe=/home/username/.venv/bin/python3, platform=linux, version='3.10.12 (main, Sep 11 2024, 15:47:36) [GCC 11.4.0]', encoding_fs_io=utf-8-utf-8) [virtualenv/discovery/builtin.py:82]
test: 275 I create virtual environment via CPython3Posix(dest=/home/username/.tox/test, clear=False, no_vcs_ignore=False, global=False) [virtualenv/run/session.py:50]
test: 275 D create folder /home/username/.tox/test/bin [virtualenv/util/path/_sync.py:12]
test: 275 D create folder /home/username/.tox/test/lib/python3.10/site-packages [virtualenv/util/path/_sync.py:12]
test: 276 D write /home/username/.tox/test/pyvenv.cfg [virtualenv/create/pyenv_cfg.py:33]
test: 276 D     home = /usr/bin [virtualenv/create/pyenv_cfg.py:38]
test: 276 D     implementation = CPython [virtualenv/create/pyenv_cfg.py:38]
test: 276 D     version_info = 3.10.12.final.0 [virtualenv/create/pyenv_cfg.py:38]
test: 276 D     virtualenv = 20.27.1 [virtualenv/create/pyenv_cfg.py:38]
test: 276 D     include-system-site-packages = false [virtualenv/create/pyenv_cfg.py:38]
test: 276 D     base-prefix = /usr [virtualenv/create/pyenv_cfg.py:38]
test: 276 D     base-exec-prefix = /usr [virtualenv/create/pyenv_cfg.py:38]
test: 276 D     base-executable = /usr/bin/python3.10 [virtualenv/create/pyenv_cfg.py:38]
test: 277 D symlink /usr/bin/python3.10 to /home/username/.tox/test/bin/python [virtualenv/util/path/_sync.py:32]
test: 277 D create virtualenv import hook file /home/username/.tox/test/lib/python3.10/site-packages/_virtualenv.pth [virtualenv/create/via_global_ref/api.py:91]
test: 277 D create /home/username/.tox/test/lib/python3.10/site-packages/_virtualenv.py [virtualenv/create/via_global_ref/api.py:94]
test: 278 D ============================== target debug ============================== [virtualenv/run/session.py:52]
test: 278 D debug via /home/username/.tox/test/bin/python /home/username/.venv/lib/python3.10/site-packages/virtualenv/create/debug.py [virtualenv/create/creator.py:200]
test: 278 D {
  "sys": {
    "executable": "/home/username/.tox/test/bin/python",
    "_base_executable": "/home/username/.tox/test/bin/python",
    "prefix": "/home/username/.tox/test",
    "base_prefix": "/usr",
    "real_prefix": null,
    "exec_prefix": "/home/username/.tox/test",
    "base_exec_prefix": "/usr",
    "path": [
      "/usr/lib/python310.zip",
      "/usr/lib/python3.10",
      "/usr/lib/python3.10/lib-dynload",
      "/home/username/.tox/test/lib/python3.10/site-packages"
    ],
    "meta_path": [
      "<class '_virtualenv._Finder'>",
      "<class '_frozen_importlib.BuiltinImporter'>",
      "<class '_frozen_importlib.FrozenImporter'>",
      "<class '_frozen_importlib_external.PathFinder'>"
    ],
    "fs_encoding": "utf-8",
    "io_encoding": "utf-8"
  },
  "version": "3.10.12 (main, Sep 11 2024, 15:47:36) [GCC 11.4.0]",
  "makefile_filename": "/usr/lib/python3.10/config-3.10-x86_64-linux-gnu/Makefile",
  "os": "<module 'os' from '/usr/lib/python3.10/os.py'>",
  "site": "<module 'site' from '/usr/lib/python3.10/site.py'>",
  "datetime": "<module 'datetime' from '/usr/lib/python3.10/datetime.py'>",
  "math": "<module 'math' (built-in)>",
  "json": "<module 'json' from '/usr/lib/python3.10/json/__init__.py'>"
} [virtualenv/run/session.py:53]
test: 311 I add seed packages via FromAppData(download=False, pip=bundle, setuptools=bundle, wheel=bundle, via=copy, app_data_dir=/home/username/.local/share/virtualenv) [virtualenv/run/session.py:57]
test: 314 D got embed update of distribution %s from ('setuptools', PosixPath('/home/username/.local/share/virtualenv/wheel/3.10/embed/3/setuptools.json')) [virtualenv/app_data/via_disk_folder.py:131]
test: 315 D got embed update of distribution %s from ('wheel', PosixPath('/home/username/.local/share/virtualenv/wheel/3.10/embed/3/wheel.json')) [virtualenv/app_data/via_disk_folder.py:131]
test: 316 D got embed update of distribution %s from ('pip', PosixPath('/home/username/.local/share/virtualenv/wheel/3.10/embed/3/pip.json')) [virtualenv/app_data/via_disk_folder.py:131]
test: 318 D using periodically updated wheel /home/username/.local/share/virtualenv/wheel/house/wheel-0.41.3-py3-none-any.whl [virtualenv/seed/wheels/periodic_update.py:48]
test: 318 D using periodically updated wheel /home/username/.local/share/virtualenv/wheel/house/setuptools-68.2.2-py3-none-any.whl [virtualenv/seed/wheels/periodic_update.py:48]
test: 319 D using periodically updated wheel /home/username/.local/share/virtualenv/wheel/house/pip-24.0-py3-none-any.whl [virtualenv/seed/wheels/periodic_update.py:48]
test: 319 D install wheel from wheel /home/username/.local/share/virtualenv/wheel/house/wheel-0.41.3-py3-none-any.whl via CopyPipInstall [virtualenv/seed/embed/via_app_data/via_app_data.py:49]
test: 320 D install setuptools from wheel /home/username/.local/share/virtualenv/wheel/house/setuptools-68.2.2-py3-none-any.whl via CopyPipInstall [virtualenv/seed/embed/via_app_data/via_app_data.py:49]
test: 320 D install pip from wheel /home/username/.local/share/virtualenv/wheel/house/pip-24.0-py3-none-any.whl via CopyPipInstall [virtualenv/seed/embed/via_app_data/via_app_data.py:49]
test: 323 D copy directory /home/username/.local/share/virtualenv/wheel/3.10/image/1/CopyPipInstall/pip-24.0-py3-none-any/pip-24.0.dist-info to /home/username/.tox/test/lib/python3.10/site-packages/pip-24.0.dist-info [virtualenv/util/path/_sync.py:40]
test: 323 D copy directory /home/username/.local/share/virtualenv/wheel/3.10/image/1/CopyPipInstall/wheel-0.41.3-py3-none-any/wheel-0.41.3.dist-info to /home/username/.tox/test/lib/python3.10/site-packages/wheel-0.41.3.dist-info [virtualenv/util/path/_sync.py:40]
test: 323 D copy directory /home/username/.local/share/virtualenv/wheel/3.10/image/1/CopyPipInstall/setuptools-68.2.2-py3-none-any/setuptools-68.2.2.dist-info to /home/username/.tox/test/lib/python3.10/site-packages/setuptools-68.2.2.dist-info [virtualenv/util/path/_sync.py:40]
test: 327 D copy directory /home/username/.local/share/virtualenv/wheel/3.10/image/1/CopyPipInstall/wheel-0.41.3-py3-none-any/wheel to /home/username/.tox/test/lib/python3.10/site-packages/wheel [virtualenv/util/path/_sync.py:40]
test: 327 D copy /home/username/.local/share/virtualenv/wheel/3.10/image/1/CopyPipInstall/setuptools-68.2.2-py3-none-any/setuptools-68.2.2.virtualenv to /home/username/.tox/test/lib/python3.10/site-packages/setuptools-68.2.2.virtualenv [virtualenv/util/path/_sync.py:40]
test: 328 D copy /home/username/.local/share/virtualenv/wheel/3.10/image/1/CopyPipInstall/pip-24.0-py3-none-any/pip-24.0.virtualenv to /home/username/.tox/test/lib/python3.10/site-packages/pip-24.0.virtualenv [virtualenv/util/path/_sync.py:40]
test: 328 D copy directory /home/username/.local/share/virtualenv/wheel/3.10/image/1/CopyPipInstall/setuptools-68.2.2-py3-none-any/setuptools to /home/username/.tox/test/lib/python3.10/site-packages/setuptools [virtualenv/util/path/_sync.py:40]
test: 329 D copy directory /home/username/.local/share/virtualenv/wheel/3.10/image/1/CopyPipInstall/pip-24.0-py3-none-any/pip to /home/username/.tox/test/lib/python3.10/site-packages/pip [virtualenv/util/path/_sync.py:40]
test: 340 D copy /home/username/.local/share/virtualenv/wheel/3.10/image/1/CopyPipInstall/wheel-0.41.3-py3-none-any/wheel-0.41.3.virtualenv to /home/username/.tox/test/lib/python3.10/site-packages/wheel-0.41.3.virtualenv [virtualenv/util/path/_sync.py:40]
test: 343 D generated console scripts wheel3 wheel wheel3.10 wheel-3.10 [virtualenv/seed/embed/via_app_data/pip_install/base.py:43]
test: 382 D copy /home/username/.local/share/virtualenv/wheel/3.10/image/1/CopyPipInstall/setuptools-68.2.2-py3-none-any/distutils-precedence.pth to /home/username/.tox/test/lib/python3.10/site-packages/distutils-precedence.pth [virtualenv/util/path/_sync.py:40]
test: 382 D copy directory /home/username/.local/share/virtualenv/wheel/3.10/image/1/CopyPipInstall/setuptools-68.2.2-py3-none-any/_distutils_hack to /home/username/.tox/test/lib/python3.10/site-packages/_distutils_hack [virtualenv/util/path/_sync.py:40]
test: 383 D copy directory /home/username/.local/share/virtualenv/wheel/3.10/image/1/CopyPipInstall/setuptools-68.2.2-py3-none-any/pkg_resources to /home/username/.tox/test/lib/python3.10/site-packages/pkg_resources [virtualenv/util/path/_sync.py:40]
test: 396 D generated console scripts  [virtualenv/seed/embed/via_app_data/pip_install/base.py:43]
test: 435 D generated console scripts pip3.10 pip3 pip pip-3.10 [virtualenv/seed/embed/via_app_data/pip_install/base.py:43]
test: 436 I add activators for Bash, CShell, Fish, Nushell, PowerShell, Python [virtualenv/run/session.py:63]
test: 438 D write /home/username/.tox/test/pyvenv.cfg [virtualenv/create/pyenv_cfg.py:33]
test: 439 D     home = /usr/bin [virtualenv/create/pyenv_cfg.py:38]
test: 439 D     implementation = CPython [virtualenv/create/pyenv_cfg.py:38]
test: 439 D     version_info = 3.10.12.final.0 [virtualenv/create/pyenv_cfg.py:38]
test: 439 D     virtualenv = 20.27.1 [virtualenv/create/pyenv_cfg.py:38]
test: 439 D     include-system-site-packages = false [virtualenv/create/pyenv_cfg.py:38]
test: 439 D     base-prefix = /usr [virtualenv/create/pyenv_cfg.py:38]
test: 439 D     base-exec-prefix = /usr [virtualenv/create/pyenv_cfg.py:38]
test: 439 D     base-executable = /usr/bin/python3.10 [virtualenv/create/pyenv_cfg.py:38]
test: 441 W commands[0]> env [tox/tox_env/api.py:427]
HOME=/home/username
TERM=xterm-256color
LANG=en_US.UTF-8
PATH=/home/username/.tox/test/bin:/home/username/.venv/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
PYTHONHASHSEED=1573952959
PIP_DISABLE_PIP_VERSION_CHECK=1
PYTHONIOENCODING=utf-8
TOX_ENV_NAME=test
TOX_WORK_DIR=/home/username/.tox
TOX_ENV_DIR=/home/username/.tox/test
VIRTUAL_ENV=/home/username/.tox/test
COLUMNS=208
LINES=44
test: 446 I exit 0 (0.00 seconds) /home/username> env pid=3704561 [tox/execute/api.py:286]
  test: OK (0.25=setup[0.24]+cmd[0.00] seconds)
  congratulations :) (0.31 seconds)

Minimal example

[testenv:test]
skip_install = true
allowlist_externals = env
setenv = 
    PATH = {env:PATH}:/test
commands = 
    env

Analysis

Issue seems caused by line 370~373 in src/tox/tox_env/api.py. _paths.setter should not modify self._env_vars directly. Remove these lines issue fixed.