Annotations for remaining Python 3.8 additions (#3358)

* Add os.add_dll_directory()
* Add memfd_create() and flags
* Add type annotation to flags
* Add stat_result.st_reparse_tag and flags
* Add ncurses_version
* Add Path.link_to()
* Add Picker.reducer_override()
* Add plistlib.UID
* Add has_dualstack_ipv6() and create_server()
* Add shlex.join()
* Add SSL methods and fields
* Add Python 3.8 statistics functions and classes
* Remove obsolete sys.subversion
* Add sys.unraisablehook
* Add threading.excepthook
* Add get_native_id() and Thread.native_id
* Add Python 3.8 tkinter methods
* Add CLOCK_UPTIME_RAW
* Add SupportsIndex
* Add typing.get_origin() and get_args()
* Add unicodedata.is_normalized
* Add unittest.mock.AsyncMock

Currently this is just an alias for Any like Mock and MagicMock. All of
these classes should probably be sub-classing Any and add their own
methods. See also #3224.

* Add unittest cleanup methods
* Add IsolatedAsyncioTestCase
* Add ElementTree.canonicalize() and C14NWriterTarget
* cProfile.Profile can be used as a context manager
* Add asyncio task name handling
* mmap.flush() now always returns None
* Add posonlyargcount to CodeType

stdlib/3/unittest/__init__.pyi

@@ -3,6 +3,7 @@
 from typing import Iterable, List, Optional, Type, Union
 from types import ModuleType
 
+from unittest.async_case import *
 from unittest.case import *
 from unittest.loader import *
 from unittest.result import *

stdlib/3/unittest/async_case.pyi

@@ -0,0 +1,9 @@
+import sys
+from typing import Any, Awaitable, Callable
+from .case import TestCase
+
+if sys.version_info >= (3, 8):
+    class IsolatedAsyncioTestCase(TestCase):
+        async def asyncSetUp(self) -> None: ...
+        async def asyncTearDown(self) -> None: ...
+        def addAsyncCleanup(self, __func: Callable[..., Awaitable[Any]], *args: Any, **kwargs: Any) -> None: ...

stdlib/3/unittest/case.pyi

@@ -1,16 +1,19 @@
+import logging
+import sys
+import unittest.result
+from types import TracebackType
 from typing import (
     Any, AnyStr, Callable, Container, ContextManager, Dict, FrozenSet, Generic,
     Iterable, List, NoReturn, Optional, overload, Pattern, Sequence, Set,
     Tuple, Type, TypeVar, Union,
 )
-import logging
-import unittest.result
-from types import TracebackType
-
 
 _E = TypeVar('_E', bound=BaseException)
 _FT = TypeVar('_FT', bound=Callable[..., Any])
 
+if sys.version_info >= (3, 8):
+    def addModuleCleanup(__function: Callable[..., Any], *args: Any, **kwargs: Any) -> None: ...
+    def doModuleCleanups() -> None: ...
 
 def expectedFailure(func: _FT) -> _FT: ...
 def skip(reason: str) -> Callable[[_FT], _FT]: ...
@@ -154,6 +157,11 @@ class TestCase:
     def addCleanup(self, function: Callable[..., Any], *args: Any,
                    **kwargs: Any) -> None: ...
     def doCleanups(self) -> None: ...
+    if sys.version_info >= (3, 8):
+        @classmethod
+        def addClassCleanup(cls, __function: Callable[..., Any], *args: Any, **kwargs: Any) -> None: ...
+        @classmethod
+        def doClassCleanups(cls) -> None: ...
     def _formatMessage(self, msg: Optional[str], standardMsg: str) -> str: ...  # undocumented
     def _getAssertEqualityFunc(self, first: Any, second: Any) -> Callable[..., None]: ...  # undocumented
     # below is deprecated

stdlib/3/unittest/mock.pyi

@@ -98,6 +98,8 @@ class MagicMixin:
 
 NonCallableMagicMock = Any
 MagicMock = Any
+if sys.version_info >= (3, 8):
+    AsyncMock = Any
 
 class MagicProxy:
     name: Any