🧪 Rewire pytest fixtures avoiding import loops

This patch also refactors and reduces the duplication of the previously
existing fixtures for retrieving different multidict module
implementations and makes the c-extension testing controllable by a CLI
option on the pytest level.

Fixes #837

.github/workflows/ci-cd.yml

@@ -261,12 +261,11 @@ jobs:
     - name: Self-install
       run: python -Im pip install '${{ steps.wheel-file.outputs.path }}'
     - name: Run unittests
-      env:
-        MULTIDICT_NO_EXTENSIONS: ${{ matrix.no-extensions }}
       run: >-
-        python -m pytest tests -vv
+        python -Im pytest tests -vv
         --cov-report xml
         --junitxml=.test-results/pytest/test.xml
+        --${{ matrix.no-extensions == 'Y' && 'no-' || '' }}c-extensions
     - name: Produce markdown test summary from JUnit
       if: >-
         !cancelled()
@@ -284,11 +283,10 @@ jobs:
       if: >-
         !cancelled()
         && failure()
-      env:
-        MULTIDICT_NO_EXTENSIONS: ${{ matrix.no-extensions }}
       run: >-  # `exit 1` makes sure that the job remains red with flaky runs
         python -Im
         pytest --no-cov -vvvvv --lf -rA
+        --${{ matrix.no-extensions == 'Y' && 'no-' || '' }}c-extensions
         && exit 1
       shell: bash
     - name: Prepare coverage artifact

.mypy.ini

@@ -25,6 +25,5 @@ warn_unreachable = True
 warn_unused_ignores = True
 warn_return_any = True
 
-[mypy-tests.*]
-disallow_any_decorated = False
-disallow_untyped_calls = False
+[mypy-test_multidict]
+disable_error_code = call-arg

.pre-commit-config.yaml

@@ -31,6 +31,21 @@ repos:
 
 - repo: local
   hooks:
+  - id: top-level-tests-init-py
+    name: changelog filenames
+    language: fail
+    entry: >-
+      The `tests/__init__.py` module must not exist so `pytest` doesn't add the
+      project root to `sys.path` / `$PYTHONPATH`
+    files: >-
+      (?x)
+      ^
+        tests/__init__\.py
+      $
+    types: []
+    types_or:
+    - file
+    - symlink
   - id: changelogs-rst
     name: changelog filenames
     language: fail

multidict/__init__.pyi

@@ -35,9 +35,15 @@ class MultiMapping(Mapping[_S, _T_co]):
     @abc.abstractmethod
     def getone(self, key: _S, default: _D) -> _T_co | _D: ...
 
-_Arg = (Mapping[str, _T] | Mapping[istr, _T] | dict[str, _T]
-        | dict[istr, _T] | MultiMapping[_T]
-        | Iterable[tuple[str, _T]] | Iterable[tuple[istr, _T]])
+_Arg = (
+    Mapping[str, _T]
+    | Mapping[istr, _T]
+    | dict[str, _T]
+    | dict[istr, _T]
+    | MultiMapping[_T]
+    | Iterable[tuple[str, _T]]
+    | Iterable[tuple[istr, _T]]
+)
 
 class MutableMultiMapping(MultiMapping[_T], MutableMapping[_S, _T], Generic[_T]):
     @abc.abstractmethod
@@ -112,9 +118,7 @@ class CIMultiDict(MutableMultiMapping[_T], Generic[_T]):
     def popall(self, key: _S, default: _D) -> list[_T] | _D: ...
 
 class MultiDictProxy(MultiMapping[_T], Generic[_T]):
-    def __init__(
-        self, arg: MultiMapping[_T] | MutableMultiMapping[_T]
-    ) -> None: ...
+    def __init__(self, arg: MultiMapping[_T] | MutableMultiMapping[_T]) -> None: ...
     def copy(self) -> MultiDict[_T]: ...
     def __getitem__(self, k: _S) -> _T: ...
     def __iter__(self) -> Iterator[_S]: ...
@@ -129,9 +133,7 @@ class MultiDictProxy(MultiMapping[_T], Generic[_T]):
     def getone(self, key: _S, default: _D) -> _T | _D: ...
 
 class CIMultiDictProxy(MultiMapping[_T], Generic[_T]):
-    def __init__(
-        self, arg: MultiMapping[_T] | MutableMultiMapping[_T]
-    ) -> None: ...
+    def __init__(self, arg: MultiMapping[_T] | MutableMultiMapping[_T]) -> None: ...
     def __getitem__(self, k: _S) -> _T: ...
     def __iter__(self) -> Iterator[_S]: ...
     def __len__(self) -> int: ...
@@ -146,5 +148,5 @@ class CIMultiDictProxy(MultiMapping[_T], Generic[_T]):
     def copy(self) -> CIMultiDict[_T]: ...
 
 def getversion(
-    md: MultiDict[_T] | CIMultiDict[_T] | MultiDictProxy[_T] | CIMultiDictProxy[_T]
+    md: MultiDict[_T] | CIMultiDict[_T] | MultiDictProxy[_T] | CIMultiDictProxy[_T],
 ) -> int: ...

multidict/_multidict_py.py

@@ -10,6 +10,7 @@
 if sys.version_info >= (3, 9):
     GenericAlias = types.GenericAlias
 else:
+
     def GenericAlias(cls):
         return cls
 

setup.cfg

@@ -67,12 +67,3 @@ norecursedirs = dist build .tox docs requirements tools
 addopts = --doctest-modules --cov=multidict --cov-report term-missing:skip-covered --cov-report xml --junitxml=junit-test-results.xml -v
 doctest_optionflags = ALLOW_UNICODE ELLIPSIS
 junit_family = xunit2
-
-[mypy]
-
-[mypy-pytest]
-ignore_missing_imports = true
-
-
-[mypy-multidict._multidict]
-ignore_missing_imports = true

tests/conftest.py

@@ -1,25 +1,160 @@
+from __future__ import annotations
+
+import argparse
 import pickle
+from dataclasses import dataclass
+from importlib import import_module
+from sys import version_info as _version_info
+from types import ModuleType
+from typing import Callable, Type
+
+try:
+    from functools import cached_property  # Python 3.8+
+except ImportError:
+    from functools import lru_cache as _lru_cache
+
+    def cached_property(func):
+        return property(_lru_cache()(func))
+
 
 import pytest
 
-from multidict._compat import USE_EXTENSIONS
+from multidict import MultiMapping, MutableMultiMapping
+
+
+PY_38_AND_BELOW = _version_info < (3, 9)
+
+
+@dataclass(frozen=True)
+class MultidictImplementation:
+    is_pure_python: bool
+
+    @cached_property
+    def tag(self) -> str:
+        return "pure-python" if self.is_pure_python else "c-extension"
+
+    @cached_property
+    def imported_module(self) -> ModuleType:
+        importable_module = "_multidict_py" if self.is_pure_python else "_multidict"
+        return import_module(f"multidict.{importable_module}")
 
-OPTIONAL_CYTHON = (
-    ()
-    if USE_EXTENSIONS
-    else pytest.mark.skip(reason="No extensions available")
+    def __str__(self):
+        return f"{self.tag}-module"
+
+
+@pytest.fixture(
+    scope="session",
+    params=(
+        MultidictImplementation(is_pure_python=False),
+        MultidictImplementation(is_pure_python=True),
+    ),
+    ids=str,
 )
+def multidict_implementation(request) -> MultidictImplementation:
+    multidict_implementation = request.param
+    test_c_extensions = request.config.getoption("--c-extensions") is True
+
+    if not test_c_extensions and not multidict_implementation.is_pure_python:
+        pytest.skip("C-extension testing not requested")
+
+    return multidict_implementation
 
 
-@pytest.fixture(  # type: ignore[call-overload]
+@pytest.fixture(scope="session")
+def multidict_module(
+    multidict_implementation: MultidictImplementation,
+) -> ModuleType:
+    return multidict_implementation.imported_module
+
+
+@pytest.fixture(
     scope="session",
-    params=[
-        pytest.param("multidict._multidict", marks=OPTIONAL_CYTHON),  # type: ignore
-        "multidict._multidict_py",
-    ],
+    params=("MultiDict", "CIMultiDict"),
+    ids=("case-sensitive", "case-insensitive"),
 )
-def _multidict(request):
-    return pytest.importorskip(request.param)
+def any_multidict_class_name(request: pytest.FixtureRequest) -> str:
+    return request.param
+
+
+@pytest.fixture(scope="session")
+def multidict_class(
+    any_multidict_class_name: str,
+    multidict_module: ModuleType,
+) -> Type[MutableMultiMapping[str]]:
+    return getattr(multidict_module, any_multidict_class_name)
+
+
+@pytest.fixture(scope="session")
+def case_sensitive_multidict_class(
+    multidict_module: ModuleType,
+) -> Type[MutableMultiMapping[str]]:
+    return multidict_module.MultiDict
+
+
+@pytest.fixture(scope="session")
+def case_insensitive_multidict_class(
+    multidict_module: ModuleType,
+) -> Type[MutableMultiMapping[str]]:
+    return multidict_module.CIMultiDict
+
+
+@pytest.fixture(scope="session")
+def case_insensitive_str_class(multidict_module: ModuleType) -> Type[str]:
+    return multidict_module.istr
+
+
+@pytest.fixture(scope="session")
+def any_multidict_proxy_class_name(any_multidict_class_name: str) -> str:
+    return f"{any_multidict_class_name}Proxy"
+
+
+@pytest.fixture(scope="session")
+def any_multidict_proxy_class(
+    any_multidict_proxy_class_name: str,
+    multidict_module: ModuleType,
+) -> Type[MultiMapping[str]]:
+    return getattr(multidict_module, any_multidict_proxy_class_name)
+
+
+@pytest.fixture(scope="session")
+def case_sensitive_multidict_proxy_class(
+    multidict_module: ModuleType,
+) -> Type[MutableMultiMapping[str]]:
+    return multidict_module.MultiDictProxy
+
+
+@pytest.fixture(scope="session")
+def case_insensitive_multidict_proxy_class(
+    multidict_module: ModuleType,
+) -> Type[MutableMultiMapping[str]]:
+    return multidict_module.CIMultiDictProxy
+
+
+@pytest.fixture(scope="session")
+def multidict_getversion_callable(multidict_module: ModuleType) -> Callable:
+    return multidict_module.getversion
+
+
+def pytest_addoption(
+    parser: pytest.Parser,
+    pluginmanager: pytest.PytestPluginManager,
+) -> None:
+    del pluginmanager
+    parser.addoption(
+        "--c-extensions",  # disabled with `--no-c-extensions`
+        action="store_true" if PY_38_AND_BELOW else argparse.BooleanOptionalAction,
+        default=True,
+        dest="c_extensions",
+        help="Test C-extensions (on by default)",
+    )
+
+    if PY_38_AND_BELOW:
+        parser.addoption(
+            "--no-c-extensions",
+            action="store_false",
+            dest="c_extensions",
+            help="Skip testing C-extensions (on by default)",
+        )
 
 
 def pytest_generate_tests(metafunc):

tests/gen_pickles.py

@@ -1,31 +1,24 @@
 import pickle
 
-from multidict._compat import USE_EXTENSIONS
-from multidict._multidict_py import CIMultiDict as PyCIMultiDict  # noqa
-from multidict._multidict_py import MultiDict as PyMultiDict  # noqa
+import multidict
 
-try:
-    from multidict._multidict import (  # type: ignore # noqa
-        CIMultiDict,
-        MultiDict,
-    )
-except ImportError:
-    pass
 
-
-def write(name, proto):
-    cls = globals()[name]
+def write(tag, cls, proto):
     d = cls([("a", 1), ("a", 2)])
-    with open("{}.pickle.{}".format(name.lower(), proto), "wb") as f:
+    file_basename = f"{cls.__name__.lower()}-{tag}"
+    with open(f"{file_basename}.pickle.{proto}", "wb") as f:
         pickle.dump(d, f, proto)
 
 
 def generate():
-    if not USE_EXTENSIONS:
-        raise RuntimeError("C Extension is required")
+    _impl_map = {
+        "c-extension": multidict._multidict,
+        "pure-python": multidict._multidict_py,
+    }
     for proto in range(pickle.HIGHEST_PROTOCOL + 1):
-        for name in ("MultiDict", "CIMultiDict", "PyMultiDict", "PyCIMultiDict"):
-            write(name, proto)
+        for tag, impl in _impl_map.items():
+            for cls in impl.CIMultiDict, impl.MultiDict:
+                write(tag, cls, proto)
 
 
 if __name__ == "__main__":