Fix open kwarg passthrough (#204)

* upath.core: handle kwargs in UPath.open
* upath: tests for open
* upath.local: support fsspec options in open

.flake8

@@ -9,6 +9,8 @@ ignore=
     # unindexed parameters in the str.format, see:
     # https://pypi.org/project/flake8-string-format/
     P1
+    # def statements on the same line with overload
+    E704
 max_line_length = 88
 max-complexity = 15
 select = B,C,E,F,W,T4,B902,T,P

upath/core.py

@@ -6,14 +6,19 @@
 from copy import copy
 from pathlib import Path
 from types import MappingProxyType
+from typing import IO
 from typing import TYPE_CHECKING
 from typing import Any
+from typing import BinaryIO
+from typing import Literal
 from typing import Mapping
+from typing import TextIO
 from typing import TypeVar
+from typing import overload
 from urllib.parse import urlsplit
 
-from fsspec import AbstractFileSystem
-from fsspec import get_filesystem_class
+from fsspec.registry import get_filesystem_class
+from fsspec.spec import AbstractFileSystem
 
 from upath._compat import FSSpecAccessorShim
 from upath._compat import PathlibPathShim
@@ -741,8 +746,64 @@ def is_socket(self):
     def samefile(self, other_path):
         raise NotImplementedError
 
-    def open(self, mode="r", buffering=-1, encoding=None, errors=None, newline=None):
-        return self.fs.open(self.path, mode)  # fixme
+    @overload
+    def open(
+        self,
+        mode: Literal["r", "w", "a"] = ...,
+        buffering: int = ...,
+        encoding: str = ...,
+        errors: str = ...,
+        newline: str = ...,
+        **fsspec_kwargs: Any,
+    ) -> TextIO: ...
+
+    @overload
+    def open(
+        self,
+        mode: Literal["rb", "wb", "ab"] = ...,
+        buffering: int = ...,
+        encoding: str = ...,
+        errors: str = ...,
+        newline: str = ...,
+        **fsspec_kwargs: Any,
+    ) -> BinaryIO: ...
+
+    def open(
+        self,
+        mode: str = "r",
+        *args: Any,
+        **fsspec_kwargs: Any,
+    ) -> IO[Any]:
+        """
+        Open the file pointed by this path and return a file object, as
+        the built-in open() function does.
+
+        Parameters
+        ----------
+        mode:
+            Opening mode. Default is 'r'.
+        buffering:
+            Default is the block size of the underlying fsspec filesystem.
+        encoding:
+            Encoding is only used in text mode. Default is None.
+        errors:
+            Error handling for encoding. Only used in text mode. Default is None.
+        newline:
+            Newline handling. Only used in text mode. Default is None.
+        **fsspec_kwargs:
+            Additional options for the fsspec filesystem.
+        """
+        # match the signature of pathlib.Path.open()
+        for key, value in zip(["buffering", "encoding", "errors", "newline"], args):
+            if key in fsspec_kwargs:
+                raise TypeError(
+                    f"{type(self).__name__}.open() got multiple values for '{key}'"
+                )
+            fsspec_kwargs[key] = value
+        # translate pathlib buffering to fs block_size
+        if "buffering" in fsspec_kwargs:
+            fsspec_kwargs.setdefault("block_size", fsspec_kwargs.pop("buffering"))
+        return self.fs.open(self.path, mode=mode, **fsspec_kwargs)
 
     def iterdir(self):
         for name in self.fs.listdir(self.path):

upath/implementations/local.py

@@ -6,6 +6,7 @@
 from pathlib import Path
 from pathlib import PosixPath
 from pathlib import WindowsPath
+from typing import IO
 from typing import Any
 from typing import Collection
 from typing import MutableMapping
@@ -110,6 +111,27 @@ class PosixUPath(PosixPath, LocalPath):
     # assign all PosixPath methods/attrs to prevent multi inheritance issues
     _set_class_attributes(locals(), src=PosixPath)
 
+    def open(
+        self,
+        mode="r",
+        buffering=-1,
+        encoding=None,
+        errors=None,
+        newline=None,
+        **fsspec_kwargs,
+    ) -> IO[Any]:
+        if fsspec_kwargs:
+            return super(LocalPath, self).open(
+                mode=mode,
+                buffering=buffering,
+                encoding=encoding,
+                errors=errors,
+                newline=newline,
+                **fsspec_kwargs,
+            )
+        else:
+            return PosixPath.open(self, mode, buffering, encoding, errors, newline)
+
     if sys.version_info < (3, 12):
 
         def __new__(
@@ -153,6 +175,27 @@ class WindowsUPath(WindowsPath, LocalPath):
     # assign all WindowsPath methods/attrs to prevent multi inheritance issues
     _set_class_attributes(locals(), src=WindowsPath)
 
+    def open(
+        self,
+        mode="r",
+        buffering=-1,
+        encoding=None,
+        errors=None,
+        newline=None,
+        **fsspec_kwargs,
+    ) -> IO[Any]:
+        if fsspec_kwargs:
+            return super(LocalPath, self).open(
+                mode=mode,
+                buffering=buffering,
+                encoding=encoding,
+                errors=errors,
+                newline=newline,
+                **fsspec_kwargs,
+            )
+        else:
+            return WindowsPath.open(self, mode, buffering, encoding, errors, newline)
+
     if sys.version_info < (3, 12):
 
         def __new__(

upath/tests/cases.py

@@ -236,7 +236,25 @@ def test_makedirs_exist_ok_false(self):
             new_dir._accessor.makedirs(new_dir, exist_ok=False)
 
     def test_open(self):
-        pass
+        p = self.path.joinpath("file1.txt")
+        with p.open(mode="r") as f:
+            assert f.read() == "hello world"
+        with p.open(mode="rb") as f:
+            assert f.read() == b"hello world"
+
+    def test_open_buffering(self):
+        p = self.path.joinpath("file1.txt")
+        p.open(buffering=-1)
+
+    def test_open_block_size(self):
+        p = self.path.joinpath("file1.txt")
+        with p.open(mode="r", block_size=8192) as f:
+            assert f.read() == "hello world"
+
+    def test_open_errors(self):
+        p = self.path.joinpath("file1.txt")
+        with p.open(mode="r", encoding="ascii", errors="strict") as f:
+            assert f.read() == "hello world"
 
     def test_owner(self):
         with pytest.raises(NotImplementedError):

upath/tests/implementations/test_data.py

@@ -92,6 +92,26 @@ def test_mkdir_parents_true_exists_ok_true(self):
     def test_mkdir_parents_true_exists_ok_false(self):
         pass
 
+    def test_open(self):
+        p = UPath("data:text/plain;base64,aGVsbG8gd29ybGQ=")
+        with p.open(mode="r") as f:
+            assert f.read() == "hello world"
+        with p.open(mode="rb") as f:
+            assert f.read() == b"hello world"
+
+    def test_open_buffering(self):
+        self.path.open(buffering=-1)
+
+    def test_open_block_size(self):
+        p = UPath("data:text/plain;base64,aGVsbG8gd29ybGQ=")
+        with p.open(mode="r", block_size=8192) as f:
+            assert f.read() == "hello world"
+
+    def test_open_errors(self):
+        p = UPath("data:text/plain;base64,aGVsbG8gd29ybGQ=")
+        with p.open(mode="r", encoding="ascii", errors="strict") as f:
+            assert f.read() == "hello world"
+
     def test_read_bytes(self, pathlib_base):
         assert len(self.path.read_bytes()) == 69