Issue #27186: Update os.fspath()/PyOS_FSPath() to check the return
type of __fspath__().
As part of this change, also make sure that the pure Python
implementation of os.fspath() is tested.
diff --git a/Lib/os.py b/Lib/os.py
index 67e1992..c31ecb2 100644
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -881,14 +881,11 @@
On Windows, use 'strict' error handler if the file system encoding is
'mbcs' (which is the default encoding).
"""
- filename = fspath(filename)
- if isinstance(filename, bytes):
- return filename
- elif isinstance(filename, str):
+ filename = fspath(filename) # Does type-checking of `filename`.
+ if isinstance(filename, str):
return filename.encode(encoding, errors)
else:
- raise TypeError("expected str, bytes or os.PathLike object, not "
- + type(filename).__name__)
+ return filename
def fsdecode(filename):
"""Decode filename (an os.PathLike, bytes, or str) from the filesystem
@@ -896,14 +893,11 @@
Windows, use 'strict' error handler if the file system encoding is
'mbcs' (which is the default encoding).
"""
- filename = fspath(filename)
- if isinstance(filename, str):
- return filename
- elif isinstance(filename, bytes):
+ filename = fspath(filename) # Does type-checking of `filename`.
+ if isinstance(filename, bytes):
return filename.decode(encoding, errors)
else:
- raise TypeError("expected str, bytes or os.PathLike object, not "
- + type(filename).__name__)
+ return filename
return fsencode, fsdecode
@@ -1102,27 +1096,44 @@
import io
return io.open(fd, *args, **kwargs)
-# Supply os.fspath() if not defined in C
+
+# For testing purposes, make sure the function is available when the C
+# implementation exists.
+def _fspath(path):
+ """Return the path representation of a path-like object.
+
+ If str or bytes is passed in, it is returned unchanged. Otherwise the
+ os.PathLike interface is used to get the path representation. If the
+ path representation is not str or bytes, TypeError is raised. If the
+ provided path is not str, bytes, or os.PathLike, TypeError is raised.
+ """
+ if isinstance(path, (str, bytes)):
+ return path
+
+ # Work from the object's type to match method resolution of other magic
+ # methods.
+ path_type = type(path)
+ try:
+ path_repr = path_type.__fspath__(path)
+ except AttributeError:
+ if hasattr(path_type, '__fspath__'):
+ raise
+ else:
+ raise TypeError("expected str, bytes or os.PathLike object, "
+ "not " + path_type.__name__)
+ if isinstance(path_repr, (str, bytes)):
+ return path_repr
+ else:
+ raise TypeError("expected {}.__fspath__() to return str or bytes, "
+ "not {}".format(path_type.__name__,
+ type(path_repr).__name__))
+
+# If there is no C implementation, make the pure Python version the
+# implementation as transparently as possible.
if not _exists('fspath'):
- def fspath(path):
- """Return the string representation of the path.
+ fspath = _fspath
+ fspath.__name__ = "fspath"
- If str or bytes is passed in, it is returned unchanged.
- """
- if isinstance(path, (str, bytes)):
- return path
-
- # Work from the object's type to match method resolution of other magic
- # methods.
- path_type = type(path)
- try:
- return path_type.__fspath__(path)
- except AttributeError:
- if hasattr(path_type, '__fspath__'):
- raise
-
- raise TypeError("expected str, bytes or os.PathLike object, not "
- + path_type.__name__)
class PathLike(abc.ABC):
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 8581865..0bfaba9 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -879,7 +879,7 @@
check_path_succeeds(PathLike(support.TESTFN.encode('utf-8')))
bad_path = PathLike(TypeError)
- with self.assertRaisesRegex(TypeError, 'invalid file'):
+ with self.assertRaises(TypeError):
self.open(bad_path, 'w')
# ensure that refcounting is correct with some error conditions
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index d34f6c6..869985e 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -3112,55 +3112,59 @@
class TestPEP519(unittest.TestCase):
- "os.fspath()"
+
+ # Abstracted so it can be overridden to test pure Python implementation
+ # if a C version is provided.
+ fspath = staticmethod(os.fspath)
+
+ class PathLike:
+ def __init__(self, path=''):
+ self.path = path
+ def __fspath__(self):
+ return self.path
def test_return_bytes(self):
for b in b'hello', b'goodbye', b'some/path/and/file':
- self.assertEqual(b, os.fspath(b))
+ self.assertEqual(b, self.fspath(b))
def test_return_string(self):
for s in 'hello', 'goodbye', 'some/path/and/file':
- self.assertEqual(s, os.fspath(s))
+ self.assertEqual(s, self.fspath(s))
- def test_fsencode_fsdecode_return_pathlike(self):
- class PathLike:
- def __init__(self, path):
- self.path = path
- def __fspath__(self):
- return self.path
-
+ def test_fsencode_fsdecode(self):
for p in "path/like/object", b"path/like/object":
- pathlike = PathLike(p)
+ pathlike = self.PathLike(p)
- self.assertEqual(p, os.fspath(pathlike))
+ self.assertEqual(p, self.fspath(pathlike))
self.assertEqual(b"path/like/object", os.fsencode(pathlike))
self.assertEqual("path/like/object", os.fsdecode(pathlike))
- def test_fspathlike(self):
- class PathLike:
- def __init__(self, path=''):
- self.path = path
- def __fspath__(self):
- return self.path
+ def test_pathlike(self):
+ self.assertEqual('#feelthegil', self.fspath(self.PathLike('#feelthegil')))
+ self.assertTrue(issubclass(self.PathLike, os.PathLike))
+ self.assertTrue(isinstance(self.PathLike(), os.PathLike))
- self.assertEqual('#feelthegil', os.fspath(PathLike('#feelthegil')))
- self.assertTrue(issubclass(PathLike, os.PathLike))
- self.assertTrue(isinstance(PathLike(), os.PathLike))
-
- message = 'expected str, bytes or os.PathLike object, not'
- for fn in (os.fsencode, os.fsdecode):
- for obj in PathLike(None), None:
- with self.assertRaisesRegex(TypeError, message):
- fn(obj)
+ with self.assertRaises(TypeError):
+ self.fspath(self.PathLike(42))
def test_garbage_in_exception_out(self):
vapor = type('blah', (), {})
for o in int, type, os, vapor():
- self.assertRaises(TypeError, os.fspath, o)
+ self.assertRaises(TypeError, self.fspath, o)
def test_argument_required(self):
with self.assertRaises(TypeError):
- os.fspath()
+ self.fspath()
+
+
+# Only test if the C version is provided, otherwise TestPEP519 already tested
+# the pure Python implementation.
+if hasattr(os, "_fspath"):
+ class TestPEP519PurePython(TestPEP519):
+
+ """Explicitly test the pure Python implementation of os.fspath()."""
+
+ fspath = staticmethod(os._fspath)
if __name__ == "__main__":