1 files changed, 115 insertions, 0 deletions
diff --git a/contrib/python/propcache/tests/conftest.py b/contrib/python/propcache/tests/conftest.py
new file mode 100644
index 00000000000..ee43f339231
--- /dev/null
+++ b/contrib/python/propcache/tests/conftest.py
@@ -0,0 +1,115 @@
+import argparse
+from dataclasses import dataclass
+from functools import cached_property
+from importlib import import_module
+from types import ModuleType
+
+import pytest
+
+C_EXT_MARK = pytest.mark.c_extension
+
+
+@dataclass(frozen=True)
+class PropcacheImplementation:
+    """A facade for accessing importable propcache module variants.
+
+    An instance essentially represents a c-extension or a pure-python module.
+    The actual underlying module is accessed dynamically through a property and
+    is cached.
+
+    It also has a text tag depending on what variant it is, and a string
+    representation suitable for use in Pytest's test IDs via parametrization.
+    """
+
+    is_pure_python: bool
+    """A flag showing whether this is a pure-python module or a C-extension."""
+
+    @cached_property
+    def tag(self) -> str:
+        """Return a text representation of the pure-python attribute."""
+        return "pure-python" if self.is_pure_python else "c-extension"
+
+    @cached_property
+    def imported_module(self) -> ModuleType:
+        """Return a loaded importable containing a propcache variant."""
+        importable_module = "_helpers_py" if self.is_pure_python else "_helpers_c"
+        return import_module(f"propcache.{importable_module}")
+
+    def __str__(self) -> str:
+        """Render the implementation facade instance as a string."""
+        return f"{self.tag}-module"
+
+
+[email protected](
+    scope="session",
+    params=(
+        pytest.param(
+            PropcacheImplementation(is_pure_python=False),
+            marks=C_EXT_MARK,
+        ),
+        PropcacheImplementation(is_pure_python=True),
+    ),
+    ids=str,
+)
+def propcache_implementation(request: pytest.FixtureRequest) -> PropcacheImplementation:
+    """Return a propcache variant facade."""
+    return request.param  # type: ignore[no-any-return]
+
+
+[email protected](scope="session")
+def propcache_module(
+    propcache_implementation: PropcacheImplementation,
+) -> ModuleType:
+    """Return a pre-imported module containing a propcache variant."""
+    return propcache_implementation.imported_module
+
+
+def pytest_addoption(
+    parser: pytest.Parser,
+    pluginmanager: pytest.PytestPluginManager,
+) -> None:
+    """Define a new ``--c-extensions`` flag.
+
+    This lets the callers deselect tests executed against the C-extension
+    version of the ``propcache`` implementation.
+    """
+    del pluginmanager
+    parser.addoption(
+        "--c-extensions",  # disabled with `--no-c-extensions`
+        action=argparse.BooleanOptionalAction,
+        default=True,
+        dest="c_extensions",
+        help="Test C-extensions (on by default)",
+    )
+
+
+def pytest_collection_modifyitems(
+    session: pytest.Session,
+    config: pytest.Config,
+    items: list[pytest.Item],
+) -> None:
+    """Deselect tests against C-extensions when requested via CLI."""
+    test_c_extensions = config.getoption("--c-extensions") is True
+
+    if test_c_extensions:
+        return
+
+    selected_tests: list[pytest.Item] = []
+    deselected_tests: list[pytest.Item] = []
+
+    for item in items:
+        c_ext = item.get_closest_marker(C_EXT_MARK.name) is not None
+
+        target_items_list = deselected_tests if c_ext else selected_tests
+        target_items_list.append(item)
+
+    config.hook.pytest_deselected(items=deselected_tests)
+    items[:] = selected_tests
+
+
+def pytest_configure(config: pytest.Config) -> None:
+    """Declare the C-extension marker in config."""
+    config.addinivalue_line(
+        "markers",
+        f"{C_EXT_MARK.name}: tests running against the C-extension implementation.",
+    )