fix: use BinaryIO instead of IO[bytes] for typing

Author: Rogdham

CHANGELOG.md

@@ -5,6 +5,14 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/), and this project
 adheres to [Semantic Versioning](https://semver.org/).
 
+## [Unreleased]
+
+[unreleased]: https://github.com/rogdham/bigxml/compare/v0.3.1...HEAD
+
+### :bug: Fixes
+
+- Typing: use `BinaryIO` instead of `IO[bytes]`
+
 ## [0.3.1] - 2021-12-26
 
 [0.3.1]: https://github.com/rogdham/python-xz/releases/tag/v0.3.1

src/xz/file.py

@@ -1,6 +1,6 @@
 from io import SEEK_CUR, SEEK_END
 import os
-from typing import IO, List, Optional
+from typing import BinaryIO, List, Optional, cast
 import warnings
 
 from xz.common import DEFAULT_CHECK, XZError
@@ -63,7 +63,7 @@ def __init__(
         # get fileobj
         if isinstance(filename, (str, bytes, os.PathLike)):
             # pylint: disable=consider-using-with, unspecified-encoding
-            self.fileobj: IO[bytes] = open(filename, self.mode + "b")
+            self.fileobj = cast(BinaryIO, open(filename, self.mode + "b"))
             self._close_fileobj = True
         elif hasattr(filename, "read"):  # weak check but better than nothing
             self.fileobj = filename

src/xz/io.py

@@ -6,17 +6,17 @@
     IOBase,
     UnsupportedOperation,
 )
-from typing import IO, Generic, Optional, TypeVar, Union, cast
+from typing import BinaryIO, Generic, Optional, TypeVar, Union, cast
 
 from xz.utils import FloorDict
 
 #
 # Typing note
 #
 # The consensus seems to favour IO instead of IOBase for typing.
-# However we cannot subclass IO[bytes] in IOAbstract as it conflicts with IOBase.
+# However we cannot subclass BinaryIO in IOAbstract as it conflicts with IOBase.
 #
-# As a result, some casting or unions between IOAbstract and IO[bytes] may be required internally.
+# As a result, some casting or unions between the two types may be required internally.
 #
 
 
@@ -41,7 +41,7 @@ def _check_not_closed(self) -> None:
 
     def fileno(self) -> int:
         try:
-            return cast(IO[bytes], self.fileobj).fileno()  # type: ignore[attr-defined]
+            return cast(BinaryIO, self.fileobj).fileno()  # type: ignore[attr-defined]
         except AttributeError:
             raise UnsupportedOperation("fileno")  # pylint: disable=raise-missing-from
 
@@ -245,7 +245,7 @@ def _read(self, size: int) -> bytes:
 class IOProxy(IOAbstract):
     def __init__(
         self,
-        fileobj: Union[IO[bytes], IOAbstract],  # see typing note on top of this file
+        fileobj: Union[BinaryIO, IOBase],  # see typing note on top of this file
         start: int,
         end: int,
     ) -> None:

src/xz/open.py

@@ -1,6 +1,6 @@
 from functools import wraps
 from io import TextIOWrapper
-from typing import IO, List, Optional, Union, cast, overload
+from typing import BinaryIO, List, Optional, Union, cast, overload
 
 from xz.file import XZFile
 from xz.typing import (
@@ -34,7 +34,7 @@ def __init__(
             filters=filters,
         )
         super().__init__(
-            cast(IO[bytes], self.xz_file),
+            cast(BinaryIO, self.xz_file),
             encoding,
             errors,
             newline,

src/xz/stream.py

@@ -1,5 +1,5 @@
 from io import SEEK_CUR
-from typing import IO, List
+from typing import BinaryIO, List
 
 from xz.block import XZBlock
 from xz.common import (
@@ -44,7 +44,7 @@ def _fileobj_blocks_end_pos(self) -> int:
         )
 
     @classmethod
-    def parse(cls, fileobj: IO[bytes]) -> "XZStream":
+    def parse(cls, fileobj: BinaryIO) -> "XZStream":
         """Parse one XZ stream from a fileobj.
 
         fileobj position should be right at the end of the stream when calling

src/xz/typing.py

@@ -1,12 +1,12 @@
 from os import PathLike
 import sys
-from typing import IO, Any, Mapping, Optional, Sequence, Union
+from typing import Any, BinaryIO, Mapping, Optional, Sequence, Union
 
 if sys.version_info >= (3, 9):  # pragma: no cover
-    _LZMAFilenameType = Union[str, bytes, PathLike[str], PathLike[bytes], IO[bytes]]
+    _LZMAFilenameType = Union[str, bytes, PathLike[str], PathLike[bytes], BinaryIO]
     from typing import Literal
 else:  # pragma: no cover
-    _LZMAFilenameType = Union[str, bytes, PathLike, IO[bytes]]
+    _LZMAFilenameType = Union[str, bytes, PathLike, BinaryIO]
 
     # ducktype Literal (NB we cannot use __class_getitem__ on Python 3.6)
     # we could require typing-extensions package but that's hardly an improvement

tests/unit/test_ioabstract.py

@@ -1,6 +1,6 @@
 from io import DEFAULT_BUFFER_SIZE, UnsupportedOperation
 from pathlib import Path
-from typing import IO
+from typing import BinaryIO
 from unittest.mock import Mock, call
 
 import pytest
@@ -27,7 +27,7 @@ def test_fileno(tmp_path: Path) -> None:
     file_path.write_bytes(b"abcd")
 
     class Impl(IOAbstract):
-        def __init__(self, fileobj: IO[bytes]) -> None:
+        def __init__(self, fileobj: BinaryIO) -> None:
             super().__init__(10)
             self.fileobj = fileobj