feature: allow testing cp38-macosx_arm64 wheel

.cirrus.yml

@@ -56,3 +56,19 @@ macos_arm64_task:
     - brew install [email protected]
     - ln -s python3 /opt/homebrew/opt/[email protected]/bin/python
   <<: *RUN_TESTS
+
+macos_arm64_cp38_task:
+  macos_instance:
+    image: ghcr.io/cirruslabs/macos-monterey-xcode
+
+  env:
+    PATH: /opt/homebrew/opt/[email protected]/bin:$PATH
+    PYTEST_ADDOPTS: --run-cp38-universal2 -k 'test_cp38_arm64_testing_universal2_installer or test_arch_auto'
+  install_pre_requirements_script:
+    - brew install [email protected]
+    - ln -s python3 /opt/homebrew/opt/[email protected]/bin/python
+    - curl -fsSLO https://www.python.org/ftp/python/3.8.10/python-3.8.10-macos11.pkg
+    - sudo installer -pkg python-3.8.10-macos11.pkg -target /
+    - rm python-3.8.10-macos11.pkg
+    - sh "/Applications/Python 3.8/Install Certificates.command"
+  <<: *RUN_TESTS

cibuildwheel/macos.py

@@ -425,6 +425,13 @@ def build(options: Options, tmp_path: Path) -> None:
 
             if build_options.test_command and build_options.test_selector(config.identifier):
                 machine_arch = platform.machine()
+                python_arch = call(
+                    "python",
+                    "-sSc",
+                    "import platform; print(platform.machine())",
+                    env=env,
+                    capture_stdout=True,
+                ).strip()
                 testing_archs: list[Literal["x86_64", "arm64"]]
 
                 if config_is_arm64:
@@ -473,7 +480,8 @@ def build(options: Options, tmp_path: Path) -> None:
                         # skip this test
                         continue
 
-                    if testing_arch == "arm64" and config.identifier.startswith("cp38-"):
+                    is_cp38 = config.identifier.startswith("cp38-")
+                    if testing_arch == "arm64" and is_cp38 and python_arch != "arm64":
                         log.warning(
                             unwrap(
                                 """

test/conftest.py

@@ -8,6 +8,12 @@ def pytest_addoption(parser) -> None:
         "--run-emulation", action="store_true", default=False, help="run emulation tests"
     )
     parser.addoption("--run-podman", action="store_true", default=False, help="run podman tests")
+    parser.addoption(
+        "--run-cp38-universal2",
+        action="store_true",
+        default=False,
+        help="macOS cp38 uses the universal2 installer",
+    )
 
 
 @pytest.fixture(

test/test_macos_archs.py

@@ -167,3 +167,33 @@ def test_cp38_arm64_testing(tmp_path, capfd):
     expected_wheels = [w for w in ALL_MACOS_WHEELS if "cp38" in w]
 
     assert set(actual_wheels) == set(expected_wheels)
+
+
+def test_cp38_arm64_testing_universal2_installer(tmp_path, capfd, request):
+    if not request.config.getoption("--run-cp38-universal2"):
+        pytest.skip("needs --run-cp38-universal2 option to run")
+
+    project_dir = tmp_path / "project"
+    basic_project.generate(project_dir)
+
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir,
+        add_env={
+            "CIBW_BUILD": "cp38-*",
+            "CIBW_TEST_COMMAND": '''python -c "import platform; print('running tests on ' + platform.machine())"''',
+            "CIBW_ARCHS": "x86_64,universal2,arm64",
+            "MACOSX_DEPLOYMENT_TARGET": "11.0",
+        },
+    )
+
+    captured = capfd.readouterr()
+
+    assert "running tests on x86_64" in captured.out
+    assert "running tests on arm64" in captured.out
+
+    warning_message = "While cibuildwheel can build CPython 3.8 universal2/arm64 wheels, we cannot test the arm64 part of them"
+    assert warning_message not in captured.err
+
+    expected_wheels = [w.replace("10_9", "11_0") for w in ALL_MACOS_WHEELS if "cp38" in w]
+
+    assert set(actual_wheels) == set(expected_wheels)

unit_test/conftest.py

@@ -11,6 +11,12 @@
 def pytest_addoption(parser):
     parser.addoption("--run-docker", action="store_true", default=False, help="run docker tests")
     parser.addoption("--run-podman", action="store_true", default=False, help="run podman tests")
+    parser.addoption(
+        "--run-cp38-universal2",
+        action="store_true",
+        default=False,
+        help="macOS cp38 uses the universal2 installer",
+    )
 
 
 @pytest.fixture