Strict typing and py.typed

mypy.ini

@@ -1,6 +1,6 @@
 [mypy]
 # Is the project well-typed?
-strict = False
+strict = True
 
 # Early opt-in even when strict = False
 warn_unused_ignores = True
@@ -12,3 +12,7 @@ explicit_package_bases = True
 
 # Disable overload-overlap due to many false-positives
 disable_error_code = overload-overlap
+
+# TODO: Raise issue upstream
+[mypy-pytest_cov.*]
+ignore_missing_imports = True

pyproject.toml

@@ -75,7 +75,3 @@ pytest11 = {enabler = "pytest_enabler"}
 
 
 [tool.setuptools_scm]
-
-
-[tool.pytest-enabler.mypy]
-# Disabled due to jaraco/skeleton#143

pytest_enabler/__init__.py

@@ -1,27 +1,46 @@
-import contextlib
+from __future__ import annotations
+
+import os
 import pathlib
 import re
 import shlex
 import sys
+from collections.abc import Container, MutableSequence, Sequence
+from typing import TYPE_CHECKING, TypeVar, overload
+
+import toml
+from jaraco.context import suppress
+from jaraco.functools import apply
+from pytest import Config, Parser
 
-if sys.version_info > (3, 12):
+if sys.version_info >= (3, 12):
     from importlib import resources
 else:
     import importlib_resources as resources
 
+if sys.version_info >= (3, 9):
+    from importlib.abc import Traversable
+else:
+    from pathlib import Path as Traversable
+
+if TYPE_CHECKING:
+    from _typeshed import SupportsRead
+    from typing_extensions import Never
 
-import toml
-from jaraco.context import suppress
-from jaraco.functools import apply
 
+_T = TypeVar("_T")
 
-consume = tuple
+consume = tuple  # type: ignore[type-arg] # Generic doesn't matter here and we need to keep it callable
 """
 Consume an iterable
 """
 
 
-def none_as_empty(ob):
+@overload
+def none_as_empty(ob: None) -> dict[Never, Never]: ...
+@overload
+def none_as_empty(ob: _T) -> _T: ...
+def none_as_empty(ob: _T | None) -> _T | dict[Never, Never]:
     """
     >>> none_as_empty({})
     {}
@@ -33,25 +52,31 @@ def none_as_empty(ob):
     return ob or {}
 
 
-def read_plugins_stream(stream):
+def read_plugins_stream(
+    stream: str | bytes | pathlib.PurePath | SupportsRead[str],
+) -> dict[str, dict[str, str]]:
     defn = toml.load(stream)
-    return defn["tool"]["pytest-enabler"]
+    return defn["tool"]["pytest-enabler"]  # type: ignore[no-any-return]
 
 
 @apply(none_as_empty)
 @suppress(Exception)
-def read_plugins(path):
+def read_plugins(path: pathlib.Path | Traversable) -> dict[str, dict[str, str]]:
     with path.open(encoding='utf-8') as stream:
         return read_plugins_stream(stream)
 
 
-def pytest_load_initial_conftests(early_config, parser, args):
+def pytest_load_initial_conftests(
+    early_config: Config,
+    parser: Parser | None,
+    args: MutableSequence[str],
+) -> None:
     plugins = {
         **read_plugins(resources.files().joinpath('default.toml')),
         **read_plugins(pathlib.Path('pyproject.toml')),
     }
 
-    def _has_plugin(name):
+    def _has_plugin(name: str) -> bool:
         pm = early_config.pluginmanager
         return pm.has_plugin(name) or pm.has_plugin('pytest_' + name)
 
@@ -61,7 +86,7 @@ def _has_plugin(name):
     _pytest_cov_check(enabled, early_config, parser, args)
 
 
-def _remove_deps():
+def _remove_deps() -> None:
     """
     Coverage will not detect function definitions as being covered
     if the functions are defined before coverage is invoked. As
@@ -82,7 +107,12 @@ def _remove_deps():
     consume(map(sys.modules.__delitem__, to_delete))
 
 
-def _pytest_cov_check(plugins, early_config, parser, args):  # pragma: nocover
+def _pytest_cov_check(
+    plugins: Container[str],
+    early_config: Config,
+    parser: Parser | None,
+    args: Sequence[str | os.PathLike[str]],
+) -> None:  # pragma: nocover
     """
     pytest_cov runs its command-line checks so early that no hooks
     can intervene. By now, the hook that installs the plugin has
@@ -99,9 +129,13 @@ def _pytest_cov_check(plugins, early_config, parser, args):  # pragma: nocover
     _remove_deps()
     # important: parse all known args to ensure pytest-cov can configure
     # itself based on other plugins like pytest-xdist (see #1).
+    if parser is None:
+        raise ValueError("parser cannot be None if cov in plugins")
     parser.parse_known_and_unknown_args(args, early_config.known_args_namespace)
 
-    with contextlib.suppress(ImportError):
+    try:
         import pytest_cov.plugin
+    except ImportError:
+        pass
 
     pytest_cov.plugin.pytest_load_initial_conftests(early_config, parser, args)

tests/test_enabler.py

@@ -1,5 +1,8 @@
+from __future__ import annotations
+
 import subprocess
 import sys
+from pathlib import Path
 from unittest import mock
 
 import pytest
@@ -8,52 +11,52 @@
 
 
 @pytest.fixture
-def pyproject(monkeypatch, tmp_path):
+def pyproject(monkeypatch: pytest.MonkeyPatch, tmp_path: Path) -> Path:
     monkeypatch.chdir(tmp_path)
     return tmp_path / 'pyproject.toml'
 
 
-def test_pytest_addoption_default():
+def test_pytest_addoption_default() -> None:
     config = mock.MagicMock()
     config.pluginmanager.has_plugin = lambda name: name == 'black'
-    args = []
+    args: list[str] = []
     enabler.pytest_load_initial_conftests(config, None, args)
     assert args == ['--black']
 
 
-def test_pytest_addoption_override(pyproject):
+def test_pytest_addoption_override(pyproject: Path) -> None:
     pyproject.write_text(
         '[tool.pytest-enabler.black]\naddopts="--black2"\n',
         encoding='utf-8',
     )
     config = mock.MagicMock()
     config.pluginmanager.has_plugin = lambda name: name == 'black'
-    args = []
+    args: list[str] = []
     enabler.pytest_load_initial_conftests(config, None, args)
     assert args == ['--black2']
 
 
-def test_pytest_addoption_disable(pyproject):
+def test_pytest_addoption_disable(pyproject: Path) -> None:
     pyproject.write_text(
         '[tool.pytest-enabler.black]\n#addopts="--black"\n',
         encoding='utf-8',
     )
     config = mock.MagicMock()
     config.pluginmanager.has_plugin = lambda name: name == 'black'
-    args = []
+    args: list[str] = []
     enabler.pytest_load_initial_conftests(config, None, args)
     assert args == []
 
 
-def test_remove_deps(monkeypatch):
+def test_remove_deps(monkeypatch: pytest.MonkeyPatch) -> None:
     """
     Invoke _remove_deps to push coverage.
     """
     monkeypatch.setattr(sys, 'modules', dict(sys.modules))
     enabler._remove_deps()
 
 
-def test_coverage_explicit(tmp_path, monkeypatch):
+def test_coverage_explicit(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
     monkeypatch.chdir(tmp_path)
     test = tmp_path.joinpath('test_x.py')
     test.write_text('def test_x():\n    pass\n', encoding='utf-8')