fix: use sys.platform instead of platform.system

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

nox/virtualenv.py

@@ -19,12 +19,10 @@
 import functools
 import json
 import os
-import platform
 import re
 import shutil
 import subprocess
 import sys
-import sysconfig
 from pathlib import Path
 from socket import gethostbyname
 from typing import TYPE_CHECKING, Any, ClassVar
@@ -65,6 +63,10 @@ def __dir__() -> list[str]:
     return __all__
 
 
+# Use for test mocking and to make mypy happy
+_PLATFORM = sys.platform
+
+
 # Problematic environment variables that are stripped from all commands inside
 # of a virtualenv. See https://github.com/theacodes/nox/issues/44
 _BLACKLISTED_ENV_VARS = frozenset(
@@ -75,8 +77,6 @@ def __dir__() -> list[str]:
         "UV_SYSTEM_PYTHON",
     ]
 )
-_SYSTEM = platform.system()
-_IS_MINGW = sysconfig.get_platform().startswith("mingw")
 
 
 def find_uv() -> tuple[bool, str]:
@@ -361,7 +361,7 @@ def _clean_location(self) -> bool:
     def bin_paths(self) -> list[str]:
         """Returns the location of the conda env's bin folder."""
         # see https://github.com/conda/conda/blob/f60f0f1643af04ed9a51da3dd4fa242de81e32f4/conda/activate.py#L563-L572
-        if _SYSTEM == "Windows":
+        if _PLATFORM.startswith("win"):
             return [
                 self.location,
                 os.path.join(self.location, "Library", "mingw-w64", "bin"),
@@ -603,7 +603,7 @@ def _resolved_interpreter(self) -> str:
 
         # The rest of this is only applicable to Windows, so if we don't have
         # an interpreter by now, raise.
-        if _SYSTEM != "Windows":
+        if not _PLATFORM.startswith("win"):
             self._resolved = InterpreterNotFound(self.interpreter)
             raise self._resolved
 
@@ -632,7 +632,7 @@ def _resolved_interpreter(self) -> str:
     @property
     def bin_paths(self) -> list[str]:
         """Returns the location of the virtualenv's bin folder."""
-        if _SYSTEM == "Windows" and not _IS_MINGW:
+        if _PLATFORM.startswith("win"):
             return [os.path.join(self.location, "Scripts")]
         return [os.path.join(self.location, "bin")]
 

noxfile.py

@@ -18,14 +18,13 @@
 import contextlib
 import functools
 import os
-import platform
 import shutil
 import sqlite3
 import sys
 
 import nox
 
-ON_WINDOWS_CI = "CI" in os.environ and platform.system() == "Windows"
+ON_WINDOWS_CI = "CI" in os.environ and sys.platform.startswith("win32")
 
 nox.needs_version = ">=2024.4.15"
 nox.options.default_venv_backend = "uv|virtualenv"

tests/test_command.py

@@ -36,12 +36,12 @@
 PYTHON = sys.executable
 
 skip_on_windows_primary_console_session = pytest.mark.skipif(
-    platform.system() == "Windows" and "SECONDARY_CONSOLE_SESSION" not in os.environ,
+    sys.platform.startswith("win") and "SECONDARY_CONSOLE_SESSION" not in os.environ,
     reason="On Windows, this test must run in a separate console session.",
 )
 
 only_on_windows = pytest.mark.skipif(
-    platform.system() != "Windows", reason="Only run this test on Windows."
+    not sys.platform.startswith("win"), reason="Only run this test on Windows."
 )
 
 
@@ -127,7 +127,7 @@ def test_run_verbosity_failed_command(
 
 
 @pytest.mark.skipif(
-    platform.system() == "Windows",
+    sys.platform.startswith("win"),
     reason="See https://github.com/python/cpython/issues/85815",
 )
 def test_run_non_str() -> None:
@@ -285,7 +285,7 @@ def enable_ctrl_c(*, enabled: bool) -> None:
 
 def interrupt_process(proc: subprocess.Popen[Any]) -> None:
     """Send SIGINT or CTRL_C_EVENT to the process."""
-    if platform.system() == "Windows":
+    if sys.platform.startswith("win"):
         # Disable Ctrl-C so we don't terminate ourselves.
         enable_ctrl_c(enabled=False)
 
@@ -301,7 +301,7 @@ def command_with_keyboard_interrupt(
     monkeypatch: pytest.MonkeyPatch, marker: Any
 ) -> None:
     """Monkeypatch Popen.communicate to raise KeyboardInterrupt."""
-    if platform.system() == "Windows":
+    if sys.platform.startswith("win"):
         # Enable Ctrl-C because the child inherits the setting from us.
         enable_ctrl_c(enabled=True)
 

tests/test_virtualenv.py

@@ -38,7 +38,7 @@
 
     from nox.virtualenv import CondaEnv, ProcessEnv, VirtualEnv
 
-IS_WINDOWS = nox.virtualenv._SYSTEM == "Windows"
+IS_WINDOWS = sys.platform.startswith("win")
 HAS_CONDA = shutil.which("conda") is not None
 HAS_UV = shutil.which("uv") is not None
 RAISE_ERROR = "RAISE_ERROR"
@@ -249,7 +249,7 @@ def test_conda_env_create_verbose(
     assert kwargs["log"]
 
 
-@mock.patch("nox.virtualenv._SYSTEM", new="Windows")
+@mock.patch("nox.virtualenv._PLATFORM", new="win32")
 def test_condaenv_bin_windows(make_conda: Callable[..., tuple[CondaEnv, Path]]) -> None:
     venv, dir_ = make_conda()
     assert [
@@ -406,7 +406,7 @@ def test_bin_paths(
     assert str(dir_.joinpath("Scripts" if IS_WINDOWS else "bin")) == venv.bin
 
 
-@mock.patch("nox.virtualenv._SYSTEM", new="Windows")
+@mock.patch("nox.virtualenv._PLATFORM", new="win32")
 def test_bin_windows(
     make_one: Callable[..., tuple[VirtualEnv | ProcessEnv, Path]],
 ) -> None:
@@ -899,7 +899,7 @@ def test__resolved_interpreter_none(
         ("2.7.15", "python2.7"),
     ],
 )
-@mock.patch("nox.virtualenv._SYSTEM", new="Linux")
+@mock.patch("nox.virtualenv._PLATFORM", new="linux")
 @mock.patch.object(shutil, "which", return_value=True)
 def test__resolved_interpreter_numerical_non_windows(
     which: mock.Mock,
@@ -914,7 +914,7 @@ def test__resolved_interpreter_numerical_non_windows(
 
 
 @pytest.mark.parametrize("input_", ["2.", "2.7."])
-@mock.patch("nox.virtualenv._SYSTEM", new="Linux")
+@mock.patch("nox.virtualenv._PLATFORM", new="linux")
 @mock.patch.object(shutil, "which", return_value=False)
 def test__resolved_interpreter_invalid_numerical_id(
     which: mock.Mock,
@@ -929,7 +929,7 @@ def test__resolved_interpreter_invalid_numerical_id(
     which.assert_called_once_with(input_)
 
 
-@mock.patch("nox.virtualenv._SYSTEM", new="Linux")
+@mock.patch("nox.virtualenv._PLATFORM", new="linux")
 @mock.patch.object(shutil, "which", return_value=False)
 def test__resolved_interpreter_32_bit_non_windows(
     which: mock.Mock, make_one: Callable[..., tuple[VirtualEnv, Path]]
@@ -941,7 +941,7 @@ def test__resolved_interpreter_32_bit_non_windows(
     which.assert_called_once_with("3.6-32")
 
 
-@mock.patch("nox.virtualenv._SYSTEM", new="Linux")
+@mock.patch("nox.virtualenv._PLATFORM", new="linux")
 @mock.patch.object(shutil, "which", return_value=True)
 def test__resolved_interpreter_non_windows(
     which: mock.Mock, make_one: Callable[..., tuple[VirtualEnv, Path]]
@@ -954,7 +954,7 @@ def test__resolved_interpreter_non_windows(
     which.assert_called_once_with("python3.6")
 
 
-@mock.patch("nox.virtualenv._SYSTEM", new="Windows")
+@mock.patch("nox.virtualenv._PLATFORM", new="win32")
 @mock.patch.object(shutil, "which")
 def test__resolved_interpreter_windows_full_path(
     which: mock.Mock, make_one: Callable[..., tuple[VirtualEnv, Path]]
@@ -976,7 +976,7 @@ def test__resolved_interpreter_windows_full_path(
         ("2.7-32", r"c:\python27\python.exe"),
     ],
 )
-@mock.patch("nox.virtualenv._SYSTEM", new="Windows")
+@mock.patch("nox.virtualenv._PLATFORM", new="win32")
 @mock.patch.object(subprocess, "run")
 @mock.patch.object(shutil, "which")
 def test__resolved_interpreter_windows_pyexe(
@@ -1011,7 +1011,7 @@ def special_run(cmd: str, *args: str, **kwargs: object) -> TextProcessResult:
     which.assert_has_calls([mock.call(input_), mock.call("py")])
 
 
-@mock.patch("nox.virtualenv._SYSTEM", new="Windows")
+@mock.patch("nox.virtualenv._PLATFORM", new="win32")
 @mock.patch.object(subprocess, "run")
 @mock.patch.object(shutil, "which")
 def test__resolved_interpreter_windows_pyexe_fails(
@@ -1020,8 +1020,8 @@ def test__resolved_interpreter_windows_pyexe_fails(
     # Establish that if the py launcher fails, we give the right error.
     venv, _ = make_one(interpreter="python3.6")
 
-    # Trick the nox.virtualenv._SYSTEM into thinking that it cannot find python3.6
-    # (it likely will on Unix). Also, when the nox.virtualenv._SYSTEM looks for the
+    # Trick the nox.virtualenv into thinking that it cannot find python3.6
+    # (it likely will on Unix). Also, when the nox.virtualenv looks for the
     # py launcher, give it a dummy that fails.
     def special_run(cmd: str, *args: str, **kwargs: object) -> TextProcessResult:  # noqa: ARG001
         return TextProcessResult("", 1)
@@ -1036,7 +1036,7 @@ def special_run(cmd: str, *args: str, **kwargs: object) -> TextProcessResult:  #
     which.assert_has_calls([mock.call("python3.6"), mock.call("py")])
 
 
-@mock.patch("nox.virtualenv._SYSTEM", new="Windows")
+@mock.patch("nox.virtualenv._PLATFORM", new="win32")
 @mock.patch("nox.virtualenv.UV_PYTHON_SUPPORT", new=False)
 def test__resolved_interpreter_windows_path_and_version(
     make_one: Callable[..., tuple[VirtualEnv, Path]],
@@ -1065,7 +1065,7 @@ def test__resolved_interpreter_windows_path_and_version(
 @pytest.mark.parametrize("input_", ["2.7", "python3.7", "goofy"])
 @pytest.mark.parametrize("sysfind_result", [r"c:\python37-x64\python.exe", None])
 @pytest.mark.parametrize("sysexec_result", ["3.7.3\\n", RAISE_ERROR])
-@mock.patch("nox.virtualenv._SYSTEM", new="Windows")
+@mock.patch("nox.virtualenv._PLATFORM", new="win32")
 @mock.patch("nox.virtualenv.UV_PYTHON_SUPPORT", new=False)
 def test__resolved_interpreter_windows_path_and_version_fails(
     input_: str,
@@ -1089,7 +1089,7 @@ def test__resolved_interpreter_windows_path_and_version_fails(
         print(venv._resolved_interpreter)
 
 
-@mock.patch("nox.virtualenv._SYSTEM", new="Windows")
+@mock.patch("nox.virtualenv._PLATFORM", new="win32")
 @mock.patch.object(shutil, "which")
 def test__resolved_interpreter_not_found(
     which: mock.Mock, make_one: Callable[..., tuple[VirtualEnv, Path]]
@@ -1106,7 +1106,7 @@ def test__resolved_interpreter_not_found(
         print(venv._resolved_interpreter)
 
 
-@mock.patch("nox.virtualenv._SYSTEM", new="Windows")
+@mock.patch("nox.virtualenv._PLATFORM", new="win32")
 @mock.patch("nox.virtualenv.locate_via_py", new=lambda _: None)  # type: ignore[misc]  # noqa: PT008
 def test__resolved_interpreter_nonstandard(
     make_one: Callable[..., tuple[VirtualEnv, Path]],
@@ -1119,7 +1119,7 @@ def test__resolved_interpreter_nonstandard(
         print(venv._resolved_interpreter)
 
 
-@mock.patch("nox.virtualenv._SYSTEM", new="Linux")
+@mock.patch("nox.virtualenv._PLATFORM", new="linux")
 @mock.patch.object(shutil, "which", return_value=True)
 def test__resolved_interpreter_cache_result(
     which: mock.Mock, make_one: Callable[..., tuple[VirtualEnv, Path]]
@@ -1135,7 +1135,7 @@ def test__resolved_interpreter_cache_result(
     assert which.call_count == 1
 
 
-@mock.patch("nox.virtualenv._SYSTEM", new="Linux")
+@mock.patch("nox.virtualenv._PLATFORM", new="linux")
 @mock.patch.object(shutil, "which", return_value=None)
 def test__resolved_interpreter_cache_failure(
     which: mock.Mock, make_one: Callable[..., tuple[VirtualEnv, Path]]