Improve integration test options (#2385)

* Improve integration test options

- Keep the platform and enable options in os.environ, don't duplicate state in utils
- Provide more user-friendly options for setting enable and platform in integration tests

* Ensure that CIBW_ENABLE is set in the test process

* Use get_enable_groups() where necessary

.github/workflows/test.yml

@@ -83,7 +83,7 @@ jobs:
           CIBW_ENABLE=all
         else
           # get the default CIBW_ENABLE value from the test module
-          CIBW_ENABLE=$(uv run --no-sync python -c 'import sys, test.conftest as c; sys.stdout.write(c.DEFAULT_CIBW_ENABLE)')
+          CIBW_ENABLE=$(uv run --no-sync python -c 'import sys, test.utils as c; sys.stdout.write(c.DEFAULT_CIBW_ENABLE)')
 
           # if this is a PR, check for labels
           if [[ -n "$GITHUB_PR_LABEL_CI_PYPY" ]]; then

docs/contributing.md

@@ -78,11 +78,11 @@ nox -s tests -- test -k before_build
 
 A few notes-
 
-- Because they run inside a container, Linux tests can run on all platforms where Docker is installed, so they're convenient for running integration tests locally. Set CIBW_PLATFORM to do this: `CIBW_PLATFORM=linux nox -s tests -- test`.
+- Because they run inside a container, Linux tests can run on all platforms where Docker is installed, so they're convenient for running integration tests locally. Set the `--platform` flag on pytest to do this: `nox -s tests -- test --platform linux`.
 
 - Running the macOS integration tests requires _system installs_ of Python from python.org for all the versions that are tested. We won't attempt to install these when running locally, but you can do so manually using the URL in the error message that is printed when the install is not found.
 
-- The 'enable groups' run by default are just 'cpython-prerelease' and 'cpython-freethreading'. You can add other groups like pypy or graalpy by setting the [CIBW_ENABLE](options.md#enable) environment variable. On GitHub PRs, you can add a label to the PR to enable these groups.
+- The ['enable groups'](options.md#enable) run by default are just 'cpython-prerelease' and 'cpython-freethreading'. You can add other groups like pypy or graalpy by passing the `--enable` argument to pytest, i.e. `nox -s tests -- test --enable pypy`. On GitHub PRs, you can add a label to the PR to enable these groups.
 
 #### Running pytest directly
 

test/conftest.py

@@ -9,12 +9,11 @@ from filelock import FileLock
 from cibuildwheel.architecture import Architecture
 from cibuildwheel.ci import detect_ci_provider
 from cibuildwheel.options import CommandLineArguments, Options
+from cibuildwheel.selector import EnableGroup
+from cibuildwheel.typing import PLATFORMS
 from cibuildwheel.venv import find_uv
 
-from .utils import EMULATED_ARCHS, platform
-
-# default to just cpython
-DEFAULT_CIBW_ENABLE = "cpython-freethreading cpython-prerelease cpython-experimental-riscv64"
+from .utils import DEFAULT_CIBW_ENABLE, EMULATED_ARCHS, get_platform
 
 
 def pytest_addoption(parser: pytest.Parser) -> None:
@@ -32,8 +31,47 @@ def pytest_addoption(parser: pytest.Parser) -> None:
         default=False,
         help="macOS cp38 uses the universal2 installer",
     )
+    parser.addoption(
+        "--enable",
+        action="store",
+        default=None,
+        help="Set the CIBW_ENABLE environment variable for all tests.",
+    )
+    parser.addoption(
+        "--platform",
+        action="store",
+        default=None,
+        help="Set the CIBW_PLATFORM environment variable for all tests.",
+    )
 
-    os.environ.setdefault("CIBW_ENABLE", DEFAULT_CIBW_ENABLE)
+
+def pytest_configure(config):
+    flag_enable = config.getoption("--enable")
+    flag_platform = config.getoption("--platform")
+
+    if flag_enable is not None and "CIBW_ENABLE" in os.environ:
+        msg = (
+            "Both --enable pytest option and CIBW_ENABLE environment variable are set. "
+            "Please specify only one."
+        )
+        raise pytest.UsageError(msg)
+    if flag_platform is not None and "CIBW_PLATFORM" in os.environ:
+        msg = (
+            "Both --platform pytest option and CIBW_PLATFORM environment variable are set. "
+            "Please specify only one."
+        )
+        raise pytest.UsageError(msg)
+
+    if flag_enable is not None:
+        EnableGroup.parse_option_value(flag_enable)
+        os.environ["CIBW_ENABLE"] = flag_enable
+    if flag_enable is None and "CIBW_ENABLE" not in os.environ:
+        # Set default value for CIBW_ENABLE
+        os.environ["CIBW_ENABLE"] = DEFAULT_CIBW_ENABLE
+
+    if flag_platform is not None:
+        assert flag_platform in PLATFORMS, f"Invalid platform: {flag_platform}"
+        os.environ["CIBW_PLATFORM"] = flag_platform
 
 
 def docker_warmup(request: pytest.FixtureRequest) -> None:
@@ -91,7 +129,7 @@ def docker_warmup_fixture(
     request: pytest.FixtureRequest, tmp_path_factory: pytest.TempPathFactory, worker_id: str
 ) -> None:
     # if we're in CI testing linux, let's warm-up docker images
-    if detect_ci_provider() is None or platform != "linux":
+    if detect_ci_provider() is None or get_platform() != "linux":
         return None
     if request.config.getoption("--run-emulation", default=None) is not None:
         # emulation tests only run one test in CI, caching the image only slows down the test
@@ -116,7 +154,7 @@ def docker_warmup_fixture(
 @pytest.fixture(params=["pip", "build"])
 def build_frontend_env_nouv(request: pytest.FixtureRequest) -> dict[str, str]:
     frontend = request.param
-    if platform == "pyodide" and frontend == "pip":
+    if get_platform() == "pyodide" and frontend == "pip":
         pytest.skip("Can't use pip as build frontend for pyodide platform")
 
     return {"CIBW_BUILD_FRONTEND": frontend}
@@ -125,7 +163,7 @@ def build_frontend_env_nouv(request: pytest.FixtureRequest) -> dict[str, str]:
 @pytest.fixture
 def build_frontend_env(build_frontend_env_nouv: dict[str, str]) -> dict[str, str]:
     frontend = build_frontend_env_nouv["CIBW_BUILD_FRONTEND"]
-    if frontend != "build" or platform == "pyodide" or find_uv() is None:
+    if frontend != "build" or get_platform() == "pyodide" or find_uv() is None:
         return build_frontend_env_nouv
 
     return {"CIBW_BUILD_FRONTEND": "build[uv]"}
@@ -134,7 +172,7 @@ def build_frontend_env(build_frontend_env_nouv: dict[str, str]) -> dict[str, str
 @pytest.fixture
 def docker_cleanup() -> Generator[None, None, None]:
     def get_images() -> set[str]:
-        if detect_ci_provider() is None or platform != "linux":
+        if detect_ci_provider() is None or get_platform() != "linux":
             return set()
         images = subprocess.run(
             ["docker", "image", "ls", "--format", "{{json .ID}}"],

test/test_0_basic.py

@@ -1,4 +1,3 @@
-import os
 import textwrap
 
 import pytest
@@ -40,7 +39,7 @@ def test(tmp_path, build_frontend_env, capfd):
     expected_wheels = utils.expected_wheels("spam", "0.1.0")
     assert set(actual_wheels) == set(expected_wheels)
 
-    enable_groups = EnableGroup.parse_option_value(os.environ.get("CIBW_ENABLE", ""))
+    enable_groups = utils.get_enable_groups()
     if EnableGroup.GraalPy not in enable_groups:
         # Verify pip warning not shown
         captured = capfd.readouterr()

test/test_abi_variants.py

@@ -47,7 +47,7 @@ def test_abi3(tmp_path):
     )
 
     # check that the expected wheels are produced
-    if utils.platform == "pyodide":
+    if utils.get_platform() == "pyodide":
         # there's only 1 possible configuration for pyodide, cp312
         expected_wheels = utils.expected_wheels("spam", "0.1.0", python_abi_tags=["cp310-abi3"])
     else:
@@ -196,7 +196,7 @@ def test_abi_none(tmp_path, capfd):
     # check that each wheel was built once, and reused
     captured = capfd.readouterr()
     assert "Building wheel..." in captured.out
-    if utils.platform == "pyodide":
+    if utils.get_platform() == "pyodide":
         # there's only 1 possible configuration for pyodide, we won't see the message expected on following builds
         assert "Found previously built wheel" not in captured.out
     else:

test/test_before_build.py

@@ -6,7 +6,7 @@ import pytest
 from . import test_projects, utils
 
 # pyodide does not support building without isolation, need to check the base_prefix
-SYS_PREFIX = f"sys.{'base_' if utils.platform == 'pyodide' else ''}prefix"
+SYS_PREFIX = f"sys.{'base_' if utils.get_platform() == 'pyodide' else ''}prefix"
 
 
 project_with_before_build_asserts = test_projects.new_c_project(
@@ -45,7 +45,7 @@ def test(tmp_path):
         f'''python -c "import pathlib, sys; pathlib.Path('{{project}}/pythonprefix_bb.txt').write_text({SYS_PREFIX})"'''
     )
     frontend = "build"
-    if utils.platform != "pyodide":
+    if utils.get_platform() != "pyodide":
         before_build = f"python -m pip install setuptools && {before_build}"
         frontend = f"{frontend};args: --no-isolation"
 

test/test_before_test.py

@@ -43,7 +43,7 @@ def test(tmp_path, build_frontend_env):
         '''python -c "import pathlib, sys; pathlib.Path('{project}/pythonprefix_bt.txt').write_text(sys.prefix)"''',
     ]
 
-    if utils.platform == "pyodide":
+    if utils.get_platform() == "pyodide":
         before_test_steps.extend(
             ["pyodide build {project}/dependency", "pip install --find-links dist/ spam"]
         )

test/test_build_frontend_args.py

@@ -20,7 +20,7 @@ def test_build_frontend_args(tmp_path, capfd, frontend_name):
 
     # the build will fail because the frontend is called with '-h' - it prints the help message
     add_env = {"CIBW_BUILD_FRONTEND": f"{frontend_name}; args: -h"}
-    if utils.platform == "pyodide":
+    if utils.get_platform() == "pyodide":
         add_env["TERM"] = "dumb"  # disable color / style
         add_env["NO_COLOR"] = "1"
     with pytest.raises(subprocess.CalledProcessError):
@@ -33,7 +33,7 @@ def test_build_frontend_args(tmp_path, capfd, frontend_name):
     if frontend_name == "pip":
         assert "Usage:" in captured.out
         assert "Wheel Options:" in captured.out
-    elif utils.platform == "pyodide":
+    elif utils.get_platform() == "pyodide":
         assert "Usage: pyodide build" in captured.out
     else:
         assert "usage:" in captured.out

test/test_container_engine.py

@@ -6,7 +6,7 @@ basic_project = test_projects.new_c_project()
 
 
 def test_podman(tmp_path, capfd, request):
-    if utils.platform != "linux":
+    if utils.get_platform() != "linux":
         pytest.skip("the test is only relevant to the linux build")
 
     if not request.config.getoption("--run-podman"):
@@ -36,7 +36,7 @@ def test_podman(tmp_path, capfd, request):
 
 
 def test_create_args(tmp_path, capfd):
-    if utils.platform != "linux":
+    if utils.get_platform() != "linux":
         pytest.skip("the test is only relevant to the linux build")
 
     project_dir = tmp_path / "project"

test/test_container_images.py

@@ -23,7 +23,7 @@ dockcross_only_project = test_projects.new_c_project(
 
 @pytest.mark.usefixtures("docker_cleanup")
 def test(tmp_path):
-    if utils.platform != "linux":
+    if utils.get_platform() != "linux":
         pytest.skip("the test is only relevant to the linux build")
     if platform.machine() not in ["x86_64", "i686"]:
         pytest.skip(

test/test_cpp_standards.py

@@ -57,7 +57,7 @@ def test_cpp11(tmp_path):
     project_dir = tmp_path / "project"
     cpp11_project = cpp_test_project.copy()
     cpp11_project.template_context["extra_compile_args"] = (
-        ["/std:c++11"] if utils.platform == "windows" else ["-std=c++11"]
+        ["/std:c++11"] if utils.get_platform() == "windows" else ["-std=c++11"]
     )
     cpp11_project.template_context["spam_cpp_top_level_add"] = "#include <array>"
     cpp11_project.generate(project_dir)
@@ -73,7 +73,7 @@ def test_cpp14(tmp_path):
     project_dir = tmp_path / "project"
     cpp14_project = cpp_test_project.copy()
     cpp14_project.template_context["extra_compile_args"] = (
-        ["/std:c++14"] if utils.platform == "windows" else ["-std=c++14"]
+        ["/std:c++14"] if utils.get_platform() == "windows" else ["-std=c++14"]
     )
     cpp14_project.template_context["spam_cpp_top_level_add"] = "int a = 100'000;"
     cpp14_project.generate(project_dir)
@@ -89,7 +89,7 @@ def test_cpp17(tmp_path):
     project_dir = tmp_path / "project"
     cpp17_project = cpp_test_project.copy()
     cpp17_project.template_context["extra_compile_args"] = [
-        "/std:c++17" if utils.platform == "windows" else "-std=c++17"
+        "/std:c++17" if utils.get_platform() == "windows" else "-std=c++17"
     ]
     cpp17_project.template_context["spam_cpp_top_level_add"] = r"""
     #include <utility>
@@ -98,7 +98,7 @@ def test_cpp17(tmp_path):
     cpp17_project.generate(project_dir)
 
     add_env = {}
-    if utils.platform == "macos":
+    if utils.get_platform() == "macos":
         add_env["MACOSX_DEPLOYMENT_TARGET"] = "10.13"
 
     actual_wheels = utils.cibuildwheel_run(project_dir, add_env=add_env, single_python=True)

test/test_dependency_versions.py

@@ -53,11 +53,15 @@ def get_versions_from_constraint_file(constraint_file: Path) -> dict[str, str]:
 
 @pytest.mark.parametrize("python_version", ["3.8", "3.12"])
 def test_pinned_versions(tmp_path, python_version, build_frontend_env_nouv):
-    if utils.platform == "linux":
+    if utils.get_platform() == "linux":
         pytest.skip("linux doesn't pin individual tool versions, it pins manylinux images instead")
-    if python_version != "3.12" and utils.platform == "pyodide":
+    if python_version != "3.12" and utils.get_platform() == "pyodide":
         pytest.skip(f"pyodide does not support Python {python_version}")
-    if python_version == "3.8" and utils.platform == "windows" and platform.machine() == "ARM64":
+    if (
+        python_version == "3.8"
+        and utils.get_platform() == "windows"
+        and platform.machine() == "ARM64"
+    ):
         pytest.skip(f"Windows ARM64 does not support Python {python_version}")
 
     project_dir = tmp_path / "project"
@@ -96,7 +100,7 @@ def test_pinned_versions(tmp_path, python_version, build_frontend_env_nouv):
 
 @pytest.mark.parametrize("method", ["inline", "file"])
 def test_dependency_constraints(method, tmp_path, build_frontend_env_nouv):
-    if utils.platform == "linux":
+    if utils.get_platform() == "linux":
         pytest.skip("linux doesn't pin individual tool versions, it pins manylinux images instead")
 
     project_dir = tmp_path / "project"
@@ -129,7 +133,7 @@ def test_dependency_constraints(method, tmp_path, build_frontend_env_nouv):
     build_environment = {}
 
     if (
-        utils.platform == "windows"
+        utils.get_platform() == "windows"
         and method == "file"
         and build_frontend_env_nouv["CIBW_BUILD_FRONTEND"] == "build"
     ):
@@ -159,7 +163,7 @@ def test_dependency_constraints(method, tmp_path, build_frontend_env_nouv):
     expected_wheels = utils.expected_wheels("spam", "0.1.0")
 
     if (
-        utils.platform == "windows"
+        utils.get_platform() == "windows"
         and method == "file"
         and build_frontend_env_nouv["CIBW_BUILD_FRONTEND"] == "build"
     ):

test/test_emulation.py

@@ -53,7 +53,7 @@ def test(tmp_path, request):
 
 
 def test_setting_arch_on_other_platforms(tmp_path, capfd):
-    if utils.platform == "linux":
+    if utils.get_platform() == "linux":
         pytest.skip("this test checks the behaviour on platforms other than linux")
 
     project_dir = tmp_path / "project"

test/test_environment.py

@@ -64,7 +64,7 @@ def test_overridden_path(tmp_path, capfd):
     output_dir.mkdir()
 
     # mess up PATH, somehow
-    if utils.platform == "linux":
+    if utils.get_platform() == "linux":
         with pytest.raises(subprocess.CalledProcessError):
             utils.cibuildwheel_run(
                 project_dir,
@@ -128,7 +128,7 @@ def test_overridden_pip_constraint(tmp_path, build_frontend):
     )
     project.generate(project_dir)
 
-    if utils.platform == "linux":
+    if utils.get_platform() == "linux":
         # put the constraints file in the project directory, so it's available
         # in the docker container
         constraints_file = project_dir / "constraints.txt"

test/test_ios.py

@@ -38,7 +38,7 @@ class TestPlatform(TestCase):
     ],
 )
 def test_ios_platforms(tmp_path, build_config, monkeypatch, capfd):
-    if utils.platform != "macos":
+    if utils.get_platform() != "macos":
         pytest.skip("this test can only run on macOS")
     if utils.get_xcode_version() < (13, 0):
         pytest.skip("this test only works with Xcode 13.0 or greater")
@@ -103,7 +103,7 @@ def test_ios_platforms(tmp_path, build_config, monkeypatch, capfd):
 
 def test_no_test_sources(tmp_path, capfd):
     """Build will fail if test-sources isn't defined."""
-    if utils.platform != "macos":
+    if utils.get_platform() != "macos":
         pytest.skip("this test can only run on macOS")
     if utils.get_xcode_version() < (13, 0):
         pytest.skip("this test only works with Xcode 13.0 or greater")
@@ -130,7 +130,7 @@ def test_no_test_sources(tmp_path, capfd):
 
 def test_missing_xbuild_tool(tmp_path, capfd):
     """Build will fail if xbuild-tools references a non-existent tool."""
-    if utils.platform != "macos":
+    if utils.get_platform() != "macos":
         pytest.skip("this test can only run on macOS")
     if utils.get_xcode_version() < (13, 0):
         pytest.skip("this test only works with Xcode 13.0 or greater")
@@ -158,7 +158,7 @@ def test_missing_xbuild_tool(tmp_path, capfd):
 
 def test_no_xbuild_tool_definition(tmp_path, capfd):
     """Build will succeed with a warning if there is no xbuild-tools definition."""
-    if utils.platform != "macos":
+    if utils.get_platform() != "macos":
         pytest.skip("this test can only run on macOS")
     if utils.get_xcode_version() < (13, 0):
         pytest.skip("this test only works with Xcode 13.0 or greater")
@@ -203,7 +203,7 @@ def test_no_xbuild_tool_definition(tmp_path, capfd):
 
 def test_empty_xbuild_tool_definition(tmp_path, capfd):
     """Build will succeed with no warning if there is an empty xbuild-tools definition."""
-    if utils.platform != "macos":
+    if utils.get_platform() != "macos":
         pytest.skip("this test can only run on macOS")
     if utils.get_xcode_version() < (13, 0):
         pytest.skip("this test only works with Xcode 13.0 or greater")

test/test_linux_python.py

@@ -7,7 +7,7 @@ from . import test_projects, utils
 
 
 def test_python_exist(tmp_path, capfd):
-    if utils.platform != "linux":
+    if utils.get_platform() != "linux":
         pytest.skip("the test is only relevant to the linux build")
     machine = platform.machine()
     if machine not in ["x86_64", "i686"]:

test/test_macos_archs.py

@@ -20,7 +20,7 @@ DEPLOYMENT_TARGET_TOO_LOW_WARNING = "Bumping MACOSX_DEPLOYMENT_TARGET"
 
 
 def test_cross_compiled_build(tmp_path):
-    if utils.platform != "macos":
+    if utils.get_platform() != "macos":
         pytest.skip("this test is only relevant to macos")
     if utils.get_xcode_version() < (12, 2):
         pytest.skip("this test only works with Xcode 12.2 or greater")
@@ -54,7 +54,7 @@ def test_cross_compiled_build(tmp_path):
     ],
 )
 def test_cross_compiled_test(tmp_path, capfd, build_universal2, test_config):
-    if utils.platform != "macos":
+    if utils.get_platform() != "macos":
         pytest.skip("this test is only relevant to macos")
     if utils.get_xcode_version() < (12, 2):
         pytest.skip("this test only works with Xcode 12.2 or greater")
@@ -114,7 +114,7 @@ def test_cross_compiled_test(tmp_path, capfd, build_universal2, test_config):
 
 def test_deployment_target_warning_is_firing(tmp_path, capfd):
     # force the warning to check that we can detect it if it happens
-    if utils.platform != "macos":
+    if utils.get_platform() != "macos":
         pytest.skip("this test is only relevant to macos")
 
     project_dir = tmp_path / "project"
@@ -136,7 +136,7 @@ def test_deployment_target_warning_is_firing(tmp_path, capfd):
 
 @pytest.mark.parametrize("skip_arm64_test", [False, True])
 def test_universal2_testing_on_x86_64(tmp_path, capfd, skip_arm64_test):
-    if utils.platform != "macos":
+    if utils.get_platform() != "macos":
         pytest.skip("this test is only relevant to macos")
     if utils.get_xcode_version() < (12, 2):
         pytest.skip("this test only works with Xcode 12.2 or greater")
@@ -176,7 +176,7 @@ def test_universal2_testing_on_x86_64(tmp_path, capfd, skip_arm64_test):
 
 def test_universal2_testing_on_arm64(build_frontend_env, tmp_path, capfd):
     # cibuildwheel should test the universal2 wheel on both x86_64 and arm64, when run on arm64
-    if utils.platform != "macos":
+    if utils.get_platform() != "macos":
         pytest.skip("this test is only relevant to macos")
     if platform.machine() != "arm64":
         pytest.skip("this test only works on arm64")
@@ -206,7 +206,7 @@ def test_universal2_testing_on_arm64(build_frontend_env, tmp_path, capfd):
 
 
 def test_cp38_arm64_testing(tmp_path, capfd, request):
-    if utils.platform != "macos":
+    if utils.get_platform() != "macos":
         pytest.skip("this test is only relevant to macos")
     if utils.get_xcode_version() < (12, 2):
         pytest.skip("this test only works with Xcode 12.2 or greater")

test/test_manylinuxXXXX_only.py

@@ -62,7 +62,7 @@ project_with_manylinux_symbols = test_projects.new_c_project(
 )
 @pytest.mark.usefixtures("docker_cleanup")
 def test(manylinux_image, tmp_path):
-    if utils.platform != "linux":
+    if utils.get_platform() != "linux":
         pytest.skip("the container image test is only relevant to the linux build")
     elif manylinux_image in {"manylinux_2_28", "manylinux_2_34"} and platform.machine() == "i686":
         pytest.skip(f"{manylinux_image} doesn't exist for i686 architecture")

test/test_musllinux_X_Y_only.py

@@ -28,7 +28,7 @@ project_with_manylinux_symbols = test_projects.new_c_project(
 )
 @pytest.mark.usefixtures("docker_cleanup")
 def test(musllinux_image, tmp_path):
-    if utils.platform != "linux":
+    if utils.get_platform() != "linux":
         pytest.skip("the container image test is only relevant to the linux build")
 
     project_dir = tmp_path / "project"

test/test_pep518.py

@@ -37,7 +37,7 @@ def test_pep518(tmp_path, build_frontend_env):
     # from a virtualenv seeded executable. See
     # https://github.com/oracle/graalpython/issues/491 and remove this once
     # fixed upstream.
-    if build_frontend_env["CIBW_BUILD_FRONTEND"] == "build" and utils.platform == "windows":
+    if build_frontend_env["CIBW_BUILD_FRONTEND"] == "build" and utils.get_platform() == "windows":
         build_frontend_env["CIBW_SKIP"] = "gp*"
 
     # build the wheels
@@ -50,7 +50,7 @@ def test_pep518(tmp_path, build_frontend_env):
     # from a virtualenv seeded executable. See
     # https://github.com/oracle/graalpython/issues/491 and remove this once
     # fixed upstream.
-    if build_frontend_env["CIBW_BUILD_FRONTEND"] == "build" and utils.platform == "windows":
+    if build_frontend_env["CIBW_BUILD_FRONTEND"] == "build" and utils.get_platform() == "windows":
         expected_wheels = [w for w in expected_wheels if "graalpy" not in w]
 
     assert set(actual_wheels) == set(expected_wheels)

test/test_troubleshooting.py

@@ -15,7 +15,7 @@ def test_failed_build_with_so_files(tmp_path, capfd, build_frontend_env, project
     if project_contains_so_files:
         project.files["libnothing.so"] = ""
 
-    if utils.platform != "linux":
+    if utils.get_platform() != "linux":
         pytest.skip("this test is only relevant to the linux build")
 
     project_dir = tmp_path / "project"
@@ -36,7 +36,7 @@ def test_failed_build_with_so_files(tmp_path, capfd, build_frontend_env, project
 
 @pytest.mark.parametrize("project_contains_so_files", [False, True])
 def test_failed_repair_with_so_files(tmp_path, capfd, project_contains_so_files):
-    if utils.platform != "linux":
+    if utils.get_platform() != "linux":
         pytest.skip("this test is only relevant to the linux build")
 
     project = new_c_project()

test/test_wheel_tag.py

@@ -6,7 +6,7 @@ basic_project = test_projects.new_c_project()
 
 
 def test_wheel_tag_is_correct_when_using_macosx_deployment_target(tmp_path):
-    if utils.platform != "macos":
+    if utils.get_platform() != "macos":
         pytest.skip("This test is only relevant to MACOSX_DEPLOYMENT_TARGET")
 
     project_dir = tmp_path / "project"

test/test_windows.py

@@ -39,7 +39,7 @@ def skip_if_no_msvc(arm64: bool = False) -> None:
 
 @pytest.mark.parametrize("use_pyproject_toml", [True, False])
 def test_wheel_tag_is_correct_when_using_windows_cross_compile(tmp_path, use_pyproject_toml):
-    if utils.platform != "windows":
+    if utils.get_platform() != "windows":
         pytest.skip("This test is only relevant to Windows")
 
     skip_if_no_msvc(arm64=True)

test/utils.py

@@ -34,18 +34,29 @@ _AARCH64_CAN_RUN_ARMV7: Final[bool] = Architecture.aarch64.value not in EMULATED
     CIProvider.cirrus_ci: False,
 }.get(detect_ci_provider(), True)
 
-platform = os.environ.get("CIBW_PLATFORM", "")
-if platform:
-    pass
-elif sys.platform.startswith("linux"):
-    platform = "linux"
-elif sys.platform.startswith("darwin"):
-    platform = "macos"
-elif sys.platform.startswith(("win32", "cygwin")):
-    platform = "windows"
-else:
-    msg = f"Unsupported platform {sys.platform!r}"
-    raise Exception(msg)
+
+def get_platform() -> str:
+    """Return the current platform as determined by CIBW_PLATFORM or sys.platform."""
+    platform = os.environ.get("CIBW_PLATFORM", "")
+    if platform:
+        return platform
+    elif sys.platform.startswith("linux"):
+        return "linux"
+    elif sys.platform.startswith("darwin"):
+        return "macos"
+    elif sys.platform.startswith(("win32", "cygwin")):
+        return "windows"
+    else:
+        msg = f"Unsupported platform {sys.platform!r}"
+        raise Exception(msg)
+
+
+DEFAULT_CIBW_ENABLE = "cpython-freethreading cpython-prerelease cpython-experimental-riscv64"
+
+
+def get_enable_groups() -> frozenset[EnableGroup]:
+    value = os.environ.get("CIBW_ENABLE", DEFAULT_CIBW_ENABLE)
+    return EnableGroup.parse_option_value(value)
 
 
 def cibuildwheel_get_build_identifiers(
@@ -74,7 +85,7 @@ def cibuildwheel_get_build_identifiers(
 def _update_pip_cache_dir(env: dict[str, str]) -> None:
     # Fix for pip concurrency bug https://github.com/pypa/pip/issues/11340
     # See https://github.com/pypa/cibuildwheel/issues/1254 for discussion.
-    if platform == "linux":
+    if get_platform() == "linux":
         return
     if "PIP_CACHE_DIR" in env:
         return
@@ -168,12 +179,12 @@ def expected_wheels(
     """
     if machine_arch is None:
         machine_arch = pm.machine()
-        if platform == "linux":
+        if get_platform() == "linux":
             machine_arch = arch_name_for_linux(machine_arch)
 
     architectures = [machine_arch]
     if not single_arch:
-        if platform == "linux":
+        if get_platform() == "linux":
             if machine_arch == "x86_64":
                 architectures.append("i686")
             elif (
@@ -182,7 +193,7 @@ def expected_wheels(
                 and _AARCH64_CAN_RUN_ARMV7
             ):
                 architectures.append("armv7l")
-        elif platform == "windows" and machine_arch == "AMD64":
+        elif get_platform() == "windows" and machine_arch == "AMD64":
             architectures.append("x86")
 
     return [
@@ -216,6 +227,8 @@ def _expected_wheels(
     """
     Returns a list of expected wheels from a run of cibuildwheel.
     """
+    platform = get_platform()
+
     # per PEP 425 (https://www.python.org/dev/peps/pep-0425/), wheel files shall have name of the form
     # {distribution}-{version}(-{build tag})?-{python tag}-{abi tag}-{platform tag}.whl
     # {python tag} and {abi tag} are closely related to the python interpreter used to build the wheel
@@ -246,6 +259,7 @@ def _expected_wheels(
             "cp313-cp313",
         ]
 
+        enable_groups = get_enable_groups()
         if EnableGroup.CPythonFreeThreading in enable_groups:
             python_abi_tags.append("cp313-cp313t")
 
@@ -378,12 +392,12 @@ def get_xcode_version() -> tuple[int, int]:
 
 
 def skip_if_pyodide(reason: str) -> Any:
-    return pytest.mark.skipif(platform == "pyodide", reason=reason)
+    return pytest.mark.skipif(get_platform() == "pyodide", reason=reason)
 
 
 def invoke_pytest() -> str:
     # see https://github.com/pyodide/pyodide/issues/4802
-    if platform == "pyodide" and sys.platform.startswith("darwin"):
+    if get_platform() == "pyodide" and sys.platform.startswith("darwin"):
         return "python -m pytest"
     return "pytest"