add unit tests to check setuptools correctly identifies windows arch

pyproject.toml

@@ -75,6 +75,7 @@ test = [
     "pytest-timeout",
     "pytest-xdist",
     "pytest>=6",
+    "setuptools",
     "tomli_w",
     "validate-pyproject",
 ]
@@ -140,6 +141,8 @@ disallow_untyped_decorators = true
 [[tool.mypy.overrides]]
 module = [
     "setuptools",
+    "setuptools._distutils", # needed even if only directly import setuptools._distutils.util
+    "setuptools._distutils.util",
     "pytest", # ignored in pre-commit to speed up check
     "bashlex",
     "bashlex.*",

unit_test/get_platform_test.py

@@ -0,0 +1,88 @@
+# ruff: noqa: ARG001
+import contextlib
+from pathlib import Path
+from typing import Dict
+
+import pytest
+import setuptools._distutils.util
+
+from cibuildwheel.windows import PythonConfiguration, setup_setuptools_cross_compile
+
+
+@contextlib.contextmanager
+def patched_environment(monkeypatch: pytest.MonkeyPatch, environment: Dict[str, str]):
+    with monkeypatch.context() as mp:
+        mp.setattr("os.name", "nt")
+        for envvar, val in environment.items():
+            mp.setenv(name=envvar, value=val)
+        yield
+
+
+def test_x86(tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
+    arch = "32"
+    environment: Dict[str, str] = {}
+
+    configuration = PythonConfiguration("irrelevant", arch, "irrelevant", None)
+
+    setup_setuptools_cross_compile(tmp_path, configuration, tmp_path, environment)
+    with patched_environment(monkeypatch, environment):
+        target_platform = setuptools._distutils.util.get_platform()
+
+    assert environment["VSCMD_ARG_TGT_ARCH"] == "x86"
+    assert target_platform == "win32"
+
+
+def test_x64(tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
+    arch = "64"
+    environment: Dict[str, str] = {}
+
+    configuration = PythonConfiguration("irrelevant", arch, "irrelevant", None)
+
+    setup_setuptools_cross_compile(tmp_path, configuration, tmp_path, environment)
+    with patched_environment(monkeypatch, environment):
+        target_platform = setuptools._distutils.util.get_platform()
+
+    assert environment["VSCMD_ARG_TGT_ARCH"] == "x64"
+    assert target_platform == "win-amd64"
+
+
+def test_arm(tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
+    arch = "ARM64"
+    environment: Dict[str, str] = {}
+
+    configuration = PythonConfiguration("irrelevant", arch, "irrelevant", None)
+
+    setup_setuptools_cross_compile(tmp_path, configuration, tmp_path, environment)
+    with patched_environment(monkeypatch, environment):
+        target_platform = setuptools._distutils.util.get_platform()
+
+    assert environment["VSCMD_ARG_TGT_ARCH"] == "arm64"
+    assert target_platform == "win-arm64"
+
+
+def test_env_set(tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
+    arch = "32"
+    environment = {"VSCMD_ARG_TGT_ARCH": "arm64"}
+
+    configuration = PythonConfiguration("irrelevant", arch, "irrelevant", None)
+
+    setup_setuptools_cross_compile(tmp_path, configuration, tmp_path, environment)
+    with patched_environment(monkeypatch, environment):
+        target_platform = setuptools._distutils.util.get_platform()
+
+    assert environment["VSCMD_ARG_TGT_ARCH"] == "arm64"
+    assert target_platform == "win-arm64"
+
+
+def test_env_blank(tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
+    arch = "32"
+    environment = {"VSCMD_ARG_TGT_ARCH": ""}
+
+    configuration = PythonConfiguration("irrelevant", arch, "irrelevant", None)
+
+    setup_setuptools_cross_compile(tmp_path, configuration, tmp_path, environment)
+    with patched_environment(monkeypatch, environment):
+        target_platform = setuptools._distutils.util.get_platform()
+
+    assert environment["VSCMD_ARG_TGT_ARCH"] == "x86"
+    assert target_platform == "win32"