Create unittest._log stub and improve _AssertLogsContext (#6428)

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

stdlib/VERSIONS

@@ -260,6 +260,7 @@ typing: 3.5-
 typing_extensions: 2.7-
 unicodedata: 2.7-
 unittest: 2.7-
+unittest._log: 3.9-
 urllib: 2.7-
 uu: 2.7-
 uuid: 2.7-

stdlib/unittest/_log.pyi

@@ -0,0 +1,27 @@
+import logging
+import sys
+from types import TracebackType
+from typing import ClassVar, Generic, NamedTuple, Type, TypeVar
+from unittest.case import TestCase
+
+_L = TypeVar("_L", None, _LoggingWatcher)
+
+class _LoggingWatcher(NamedTuple):
+    records: list[logging.LogRecord]
+    output: list[str]
+
+class _AssertLogsContext(Generic[_L]):
+    LOGGING_FORMAT: ClassVar[str]
+    test_case: TestCase
+    logger_name: str
+    level: int
+    msg: None
+    if sys.version_info >= (3, 10):
+        def __init__(self, test_case: TestCase, logger_name: str, level: int, no_logs: bool) -> None: ...
+        no_logs: bool
+    else:
+        def __init__(self, test_case: TestCase, logger_name: str, level: int) -> None: ...
+    def __enter__(self) -> _L: ...
+    def __exit__(
+        self, exc_type: Type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
+    ) -> bool | None: ...

stdlib/unittest/case.pyi

@@ -14,7 +14,6 @@ from typing import (
     Generic,
     Iterable,
     Mapping,
-    NamedTuple,
     NoReturn,
     Pattern,
     Sequence,
@@ -23,6 +22,7 @@ from typing import (
     TypeVar,
     overload,
 )
+from unittest._log import _AssertLogsContext, _LoggingWatcher
 from warnings import WarningMessage
 
 if sys.version_info >= (3, 9):
@@ -30,7 +30,6 @@ if sys.version_info >= (3, 9):
 
 _E = TypeVar("_E", bound=BaseException)
 _FT = TypeVar("_FT", bound=Callable[..., Any])
-_L = TypeVar("_L", None, _LoggingWatcher)
 
 if sys.version_info >= (3, 8):
     def addModuleCleanup(__function: Callable[..., Any], *args: Any, **kwargs: Any) -> None: ...
@@ -251,10 +250,6 @@ class FunctionTestCase(TestCase):
     ) -> None: ...
     def runTest(self) -> None: ...
 
-class _LoggingWatcher(NamedTuple):
-    records: list[logging.LogRecord]
-    output: list[str]
-
 class _AssertRaisesContext(Generic[_E]):
     exception: _E
     def __enter__(self: Self) -> Self: ...
@@ -273,16 +268,3 @@ class _AssertWarnsContext:
     def __exit__(
         self, exc_type: Type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
     ) -> None: ...
-
-class _AssertLogsContext(Generic[_L]):
-    LOGGING_FORMAT: str
-    records: list[logging.LogRecord]
-    output: list[str]
-    if sys.version_info >= (3, 10):
-        def __init__(self, test_case: TestCase, logger_name: str, level: int, no_logs: bool) -> None: ...
-    else:
-        def __init__(self, test_case: TestCase, logger_name: str, level: int) -> None: ...
-    def __enter__(self) -> _L: ...
-    def __exit__(
-        self, exc_type: Type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
-    ) -> bool | None: ...

tests/stubtest_allowlists/py36.txt

@@ -60,6 +60,7 @@ typing.NamedTuple._make
 typing.NamedTuple._replace
 typing.Sequence.index
 typing.runtime_checkable
+unittest._log  # New in Python 3.9
 unittest.async_case  # Added in Python 3.8
 uuid.UUID.int
 xml.etree.ElementTree.TreeBuilder.start  # Discrepancy between Python and C modules, fixed in bpo-39495

tests/stubtest_allowlists/py37.txt

@@ -53,6 +53,7 @@ typing.NamedTuple._replace
 typing._SpecialForm.__init__
 typing._SpecialForm.__new__
 typing.runtime_checkable
+unittest._log  # New in Python 3.9
 unittest.async_case  # Added in Python 3.8
 uuid.UUID.int
 uuid.UUID.is_safe

tests/stubtest_allowlists/py38.txt

@@ -73,6 +73,7 @@ typing.SupportsInt.__init__
 typing.SupportsRound.__init__
 typing._SpecialForm.__init__
 typing._SpecialForm.__new__
+unittest._log  # New in Python 3.9
 uuid.getnode  # undocumented, unused parameter getters that was later removed
 weakref.WeakValueDictionary.update
 xml.etree.ElementTree.TreeBuilder.start  # Discrepancy between Python and C modules, fixed in bpo-39495