Merge pull request testing-cabal#587 from stephenfin/typing

More type improvements

Author: jelmer

testtools/matchers/_basic.py

@@ -18,7 +18,7 @@
 
 import operator
 import re
-from collections.abc import Callable
+from collections.abc import Callable, Sized
 from pprint import pformat
 from typing import Any, Generic, TypeVar
 
@@ -459,7 +459,7 @@ def match(self, value: str) -> Mismatch | None:
         return None
 
 
-def has_len(x: Any, y: int) -> bool:
+def has_len(x: Sized, y: int) -> bool:
     return len(x) == y
 
 

testtools/monkey.py

@@ -3,7 +3,10 @@
 """Helpers for monkey-patching Python code."""
 
 from collections.abc import Callable
-from typing import Any
+from typing import ParamSpec, TypeVar
+
+_P = ParamSpec("_P")
+_R = TypeVar("_R")
 
 __all__ = [
     "MonkeyPatcher",
@@ -71,7 +74,9 @@ def restore(self) -> None:
             else:
                 setattr(obj, name, value)
 
-    def run_with_patches(self, f: Callable[..., Any], *args: Any, **kw: Any) -> Any:
+    def run_with_patches(
+        self, f: Callable[_P, _R], *args: _P.args, **kw: _P.kwargs
+    ) -> _R:
         """Run 'f' with the given args and kwargs with all patches applied.
 
         Restores all objects to their original state when finished.

testtools/runtest.py

@@ -9,7 +9,7 @@
 
 import sys
 from collections.abc import Callable
-from typing import TYPE_CHECKING, Any
+from typing import TYPE_CHECKING, Any, NoReturn
 
 from testtools.testresult import (
     ExcInfo,
@@ -252,7 +252,7 @@ def _got_user_exception(
         return self.exception_caught
 
 
-def _raise_force_fail_error() -> None:
+def _raise_force_fail_error() -> NoReturn:
     raise AssertionError("Forced Test Failure")
 
 

testtools/testcase.py

@@ -23,11 +23,14 @@
 import types
 import unittest
 from collections.abc import Callable, Iterator
-from typing import TYPE_CHECKING, NoReturn, ParamSpec, TypeVar, cast, overload
+from typing import TYPE_CHECKING, Generic, NoReturn, ParamSpec, TypeVar, cast, overload
 from unittest.case import SkipTest
 
 T = TypeVar("T")
 U = TypeVar("U")
+_E = TypeVar("_E", bound=BaseException)
+_E2 = TypeVar("_E2", bound=BaseException)
+_E3 = TypeVar("_E3", bound=BaseException)
 
 # ruff: noqa: E402 - TypeVars must be defined before importing testtools modules
 from testtools import content
@@ -513,17 +516,38 @@ def assertRaises(
     @overload  # type: ignore[override]
     def assertRaises(
         self,
-        expected_exception: type[BaseException] | tuple[type[BaseException]],
+        expected_exception: type[_E],
         callable: None = ...,
-    ) -> "_AssertRaisesContext": ...
+    ) -> "_AssertRaisesContext[_E]": ...
 
-    def assertRaises(  # type: ignore[override]
+    @overload  # type: ignore[override]
+    def assertRaises(
         self,
-        expected_exception: type[BaseException] | tuple[type[BaseException]],
+        expected_exception: tuple[type[_E], type[_E2]],
+        callable: None = ...,
+    ) -> "_AssertRaisesContext[_E | _E2]": ...
+
+    @overload  # type: ignore[override]
+    def assertRaises(
+        self,
+        expected_exception: tuple[type[_E], type[_E2], type[_E3]],
+        callable: None = ...,
+    ) -> "_AssertRaisesContext[_E | _E2 | _E3]": ...
+
+    @overload  # type: ignore[override]
+    def assertRaises(
+        self,
+        expected_exception: tuple[type[BaseException], ...],
+        callable: None = ...,
+    ) -> "_AssertRaisesContext[BaseException]": ...
+
+    def assertRaises(  # type: ignore[override, misc]
+        self,
+        expected_exception: type[BaseException] | tuple[type[BaseException], ...],
         callable: Callable[_P, _R] | None = None,
         *args: _P.args,
         **kwargs: _P.kwargs,
-    ) -> "_AssertRaisesContext | BaseException":
+    ) -> "_AssertRaisesContext[BaseException] | BaseException":
         """Fail unless an exception of class expected_exception is thrown
         by callable when invoked with arguments args and keyword
         arguments kwargs. If a different type of exception is
@@ -1185,7 +1209,7 @@ def decorator(test_item: _F) -> _F:
         if not isinstance(test_item, class_types):
 
             @functools.wraps(test_item)
-            def skip_wrapper(*args: object, **kwargs: object) -> None:
+            def skip_wrapper(*args: object, **kwargs: object) -> NoReturn:
                 raise TestCase.skipException(reason)
 
             test_item = cast(_F, skip_wrapper)
@@ -1223,15 +1247,15 @@ def _id(obj: _F) -> _F:
     return _id
 
 
-class _AssertRaisesContext:
+class _AssertRaisesContext(Generic[_E]):
     """A context manager to handle expected exceptions for assertRaises.
 
     This provides compatibility with unittest's assertRaises context manager.
     """
 
     def __init__(
         self,
-        expected: type[BaseException] | tuple[type[BaseException]],
+        expected: type[_E] | tuple[type[BaseException], ...],
         test_case: TestCase,
         msg: str | None = None,
     ) -> None:
@@ -1244,7 +1268,7 @@ def __init__(
         self.expected = expected
         self.test_case = test_case
         self.msg = msg
-        self.exception: BaseException | None = None
+        self.exception: _E | None = None
 
     def __enter__(self) -> "Self":
         return self
@@ -1274,7 +1298,7 @@ def __exit__(
             # let unexpected exceptions pass through
             return False
         # store exception for later retrieval
-        self.exception = exc_value
+        self.exception = cast(_E, exc_value)
         return True
 
 
@@ -1341,7 +1365,7 @@ def __exit__(
         return True
 
 
-class Nullary:
+class Nullary(Generic[_R]):
     """Turn a callable into a nullary callable.
 
     The advantage of this over ``lambda: f(*args, **kwargs)`` is that it
@@ -1358,7 +1382,7 @@ def __init__(
         self._args = args
         self._kwargs = kwargs
 
-    def __call__(self) -> object:
+    def __call__(self) -> _R:
         return self._callable_object(*self._args, **self._kwargs)
 
     def __repr__(self) -> str: