tests: add a cross-compile test

Signed-off-by: Henry Schreiner <[email protected]>

src/scikit_build_core/builder/cross_compile.py

@@ -9,7 +9,7 @@
 
 from .._logging import logger
 
-__all__ = ["set_cross_compile_env"]
+__all__ = ["set_cross_compile_env", "auto_cross_compile_env"]
 
 
 def __dir__() -> list[str]:

tests/test_cross_compile.py

@@ -0,0 +1,36 @@
+from __future__ import annotations
+
+import os
+import subprocess
+import sys
+import sysconfig
+
+import pytest
+
+from scikit_build_core.builder.cross_compile import set_cross_compile_env
+
+
+@pytest.mark.skipif(
+    sysconfig.get_config_var("SOABI") != "cp311-win_amd64",
+    reason="Only tests 'cp311-win_amd64', got {sysconfig.get_config_var('SOABI')!r}",
+)
+def test_environment():
+    env = os.environ.copy()
+    cmd = [
+        sys.executable,
+        "-c",
+        "import sysconfig; print(sysconfig.get_config_var('SOABI'), sysconfig.get_config_var('EXT_SUFFIX'))",
+    ]
+
+    with set_cross_compile_env(".cp311-win_arm64.pyd", env):
+        result = subprocess.run(
+            cmd, check=True, capture_output=True, text=True, env=env
+        )
+        soabi, ext_suffix = result.stdout.strip().split()
+        assert soabi == "cp311-win_arm64"
+        assert ext_suffix == ".cp311-win_arm64.pyd"
+
+    result = subprocess.run(cmd, check=True, capture_output=True, text=True, env=env)
+    soabi, ext_suffix = result.stdout.strip().split()
+    assert soabi == "cp311-win_amd64"
+    assert ext_suffix == ".cp311-win_amd64.pyd"