Add typing to test suite

Signed-off-by: Bernát Gábor <bgabor8@bloomberg.net>

8 files changed, 48 insertions, 46 deletions

diff --git a/src/tox/config/cli/parser.py b/src/tox/config/cli/parser.py
index 93bdb5d8..36fdb0a4 100644
--- a/src/tox/config/cli/parser.py
+++ b/src/tox/config/cli/parser.py
@@ -6,27 +6,9 @@ import argparse
 import logging
 import os
 import sys
-from argparse import (
-    SUPPRESS,
-    Action,
-    ArgumentDefaultsHelpFormatter,
-    ArgumentParser,
-    Namespace,
-    _SubParsersAction,
-)
+from argparse import SUPPRESS, Action, ArgumentDefaultsHelpFormatter, ArgumentParser, Namespace, _SubParsersAction
 from itertools import chain
-from typing import (
-    Any,
-    Callable,
-    Dict,
-    List,
-    Optional,
-    Sequence,
-    Tuple,
-    Type,
-    TypeVar,
-    cast,
-)
+from typing import Any, Callable, Dict, List, Optional, Sequence, Tuple, Type, TypeVar, cast
 
 from tox.config.source.ini.convert import StrConvert
 from tox.plugin import NAME
diff --git a/src/tox/config/sets.py b/src/tox/config/sets.py
index e6e900ad..448bbad0 100644
--- a/src/tox/config/sets.py
+++ b/src/tox/config/sets.py
@@ -137,22 +137,26 @@ class ConfigSet:
         desc: str,
         post_process: Optional[Callable[[V, "Config"], V]] = None,
         overwrite: bool = False,
-    ) -> None:
+    ) -> ConfigDynamicDefinition[V]:
         """
         Add configuration value.
         """
         keys_ = self._make_keys(keys)
         for key in keys_:
             if key in self._defined and overwrite is False:
-                # already added
-                return
+                defined = self._defined[key]
+                if isinstance(defined, ConfigDynamicDefinition):
+                    return defined
+                raise TypeError(f"{keys} already defined with differing type {type(defined).__name__}")
         definition = ConfigDynamicDefinition(keys_, of_type, default, desc, post_process)
         self._add_conf(keys_, definition)
+        return definition
 
-    def add_constant(self, keys: Sequence[str], desc: str, value: V) -> None:
+    def add_constant(self, keys: Sequence[str], desc: str, value: V) -> ConfigConstantDefinition[V]:
         keys_ = self._make_keys(keys)
         definition = ConfigConstantDefinition(keys_, desc, value)
         self._add_conf(keys, definition)
+        return definition
 
     def make_package_conf(self) -> None:
         self._raw.make_package_conf()
diff --git a/src/tox/config/source/ini/__init__.py b/src/tox/config/source/ini/__init__.py
index b8be6779..f96bd2e1 100644
--- a/src/tox/config/source/ini/__init__.py
+++ b/src/tox/config/source/ini/__init__.py
@@ -222,4 +222,6 @@ class ToxIni(Source):
 __all__ = (
     "ToxIni",
     "IniLoader",
+    "filter_for_env",
+    "find_envs",
 )
diff --git a/src/tox/execute/local_sub_process/read_via_thread_unix.py b/src/tox/execute/local_sub_process/read_via_thread_unix.py
index a5b1b69b..b16b0c66 100644
--- a/src/tox/execute/local_sub_process/read_via_thread_unix.py
+++ b/src/tox/execute/local_sub_process/read_via_thread_unix.py
@@ -27,7 +27,10 @@ class ReadViaThreadUnix(ReadViaThread):
     def _drain_stream(self) -> bytes:
         result = bytearray()  # on closed file read returns empty
         while True:
-            last_result = os.read(self.file_no, 1)
+            try:
+                last_result = os.read(self.file_no, 1)
+            except OSError:  # ignore failing to read the pipe - already closed
+                break
             if last_result:
                 result.append(last_result[0])
             else:
diff --git a/src/tox/pytest.py b/src/tox/pytest.py
index 1fd7c22d..1da38fce 100644
--- a/src/tox/pytest.py
+++ b/src/tox/pytest.py
@@ -7,10 +7,11 @@ import sys
 import textwrap
 from contextlib import contextmanager
 from pathlib import Path
-from typing import Any, Callable, Dict, Iterator, List, Optional, Sequence
+from typing import TYPE_CHECKING, Any, Callable, Dict, Iterator, List, Optional, Sequence
 
 import pytest
-from _pytest.capture import CaptureFixture
+from _pytest.capture import CaptureFixture as _CaptureFixture
+from _pytest.logging import LogCaptureFixture
 from _pytest.monkeypatch import MonkeyPatch
 
 import tox.run
@@ -23,6 +24,11 @@ from tox.run import setup_state as previous_setup_state
 from tox.session.cmd.run.parallel import ENV_VAR_KEY
 from tox.session.state import State
 
+if TYPE_CHECKING:
+    CaptureFixture = _CaptureFixture[str]
+else:
+    CaptureFixture = _CaptureFixture
+
 
 @pytest.fixture(autouse=True)
 def ensure_logging_framework_not_altered() -> Iterator[None]:
@@ -77,7 +83,7 @@ class ToxProject:
         self,
         files: Dict[str, Any],
         path: Path,
-        capsys: CaptureFixture[str],
+        capsys: CaptureFixture,
         monkeypatch: MonkeyPatch,
     ) -> None:
         self.path = path
@@ -156,7 +162,13 @@ class ToxRunOutcome:
         self.code: int = code
         self.out: str = out
         self.err: str = err
-        self.state: Optional[State] = state
+        self._state: Optional[State] = state
+
+    @property
+    def state(self) -> State:
+        if self._state is None:
+            raise RuntimeError("no state")
+        return self._state
 
     @property
     def success(self) -> bool:
@@ -188,7 +200,7 @@ ToxProjectCreator = Callable[[Dict[str, Any]], ToxProject]
 
 
 @pytest.fixture(name="tox_project")
-def init_fixture(tmp_path: Path, capsys: CaptureFixture[str], monkeypatch: MonkeyPatch) -> ToxProjectCreator:
+def init_fixture(tmp_path: Path, capsys: CaptureFixture, monkeypatch: MonkeyPatch) -> ToxProjectCreator:
     def _init(files: Dict[str, Any]) -> ToxProject:
         """create tox  projects"""
         return ToxProject(files, tmp_path, capsys, monkeypatch)
@@ -201,3 +213,14 @@ def empty_project(tox_project: ToxProjectCreator, monkeypatch: MonkeyPatch) -> T
     project = tox_project({"tox.ini": ""})
     monkeypatch.chdir(project.path)
     return project
+
+
+__all__ = (
+    "CaptureFixture",
+    "LogCaptureFixture",
+    "MonkeyPatch",
+    "ToxRunOutcome",
+    "ToxProject",
+    "ToxProjectCreator",
+    "check_os_environ",
+)
diff --git a/src/tox/session/cmd/show_config.py b/src/tox/session/cmd/show_config.py
index 3fef8f83..e335fab3 100644
--- a/src/tox/session/cmd/show_config.py
+++ b/src/tox/session/cmd/show_config.py
@@ -19,7 +19,7 @@ def tox_add_option(parser: ToxParser) -> None:
     env_list_flag(our)
 
 
-def display_config(state: State) -> None:
+def display_config(state: State) -> int:
     first = True
     if not state.options.env:
         print("[tox]")
@@ -33,6 +33,7 @@ def display_config(state: State) -> None:
         print(f"[testenv:{name}]")
         print(f"type = {type(tox_env).__name__}")
         print_conf(tox_env.conf)
+    return 0
 
 
 def print_conf(conf: ConfigSet) -> None:
diff --git a/src/tox/tox_env/python/api.py b/src/tox/tox_env/python/api.py
index 88cd79ad..567f404d 100644
--- a/src/tox/tox_env/python/api.py
+++ b/src/tox/tox_env/python/api.py
@@ -4,17 +4,7 @@ Declare the abstract base class for tox environments that handle the Python lang
 import sys
 from abc import ABC, abstractmethod
 from pathlib import Path
-from typing import (
-    Any,
-    Dict,
-    List,
-    NamedTuple,
-    NoReturn,
-    Optional,
-    Sequence,
-    Union,
-    cast,
-)
+from typing import Any, Dict, List, NamedTuple, NoReturn, Optional, Sequence, Union, cast
 
 from packaging.requirements import Requirement
 from virtualenv.discovery.py_spec import PythonSpec
diff --git a/src/tox/tox_env/python/virtual_env/package/api.py b/src/tox/tox_env/python/virtual_env/package/api.py
index 0e7151ad..16277c31 100644
--- a/src/tox/tox_env/python/virtual_env/package/api.py
+++ b/src/tox/tox_env/python/virtual_env/package/api.py
@@ -17,10 +17,7 @@ from tox.tox_env.python.package import PythonPackage
 from ..api import VirtualEnv
 
 try:
-    from importlib.metadata import (  # type: ignore[attr-defined]
-        Distribution,
-        PathDistribution,
-    )
+    from importlib.metadata import Distribution, PathDistribution  # type: ignore[attr-defined]
 except ImportError:
     from importlib_metadata import Distribution, PathDistribution  # noqa