Remove "in the fake filesystem" from OSError message

- makes it more consistent with real messages
- documentation: add a few links to the intro

Author: mrbean-bremen

CHANGES.md

@@ -14,6 +14,10 @@ The released versions correspond to PyPI releases.
 
 ## Unreleased
 
+### Changes
+* the message from an `OSError` raised in the fake filesystem has no longer the postfix
+  _"in the fake filesystem"_ (see [#1159](../../discussions/1159))
+
 ### Enhancements
 * added convenience function `add_package_metadata` to add the metadata of a given
   package to the fake filesystem (see [#1155](../../issues/1155))

docs/convenience.rst

@@ -214,6 +214,8 @@ and you may fail to create new files if the fake file system is full.
 To get the file system size, you may use :py:meth:`get_disk_usage()<pyfakefs.fake_filesystem.FakeFilesystem.get_disk_usage>`, which is
 modeled after ``shutil.disk_usage()``.
 
+.. _pause_resume:
+
 Suspending patching
 ~~~~~~~~~~~~~~~~~~~
 Sometimes, you may want to access the real filesystem inside the test with
@@ -262,6 +264,8 @@ Here is the same code using a context manager:
         assert not os.path.exists(real_temp_file.name)
         assert os.path.exists(fake_temp_file.name)
 
+.. _simulate_os:
+
 Simulating other file systems
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 ``Pyfakefs`` supports Linux, macOS and Windows operating systems. By default,

docs/intro.rst

@@ -34,29 +34,29 @@ Features
   the real filesystem will work on the fake filesystem if running under
   ``pyfakefs``.
 
-- ``pyfakefs`` provides direct support for `pytest` (via the `fs` fixture)
-  and `unittest` (via a `TestCase` base class), but can also be used with
+- ``pyfakefs`` provides direct support for `pytest` (see :ref:`pytest_plugin`)
+  and `unittest` (see :ref:`unittest_usage`), but can also be used with
   other test frameworks.
 
 - Each ``pyfakefs`` test starts with an empty (except for the :ref:`os_temporary_directories`) file system,
   but it is possible to map files and directories from the real file system into the fake
-  filesystem if needed.
+  filesystem if needed (see :ref:`real_fs_access`).
 
 - No files in the real file system are changed during the tests, even in the
   case of writing to mapped real files.
 
 - ``pyfakefs`` keeps track of the filesystem size if configured. The file system
-  size can be configured arbitrarily. It is also possible to create files with a defined
-  size without setting contents.
+  size can be configured arbitrarily (see :ref:`set-fs-size`). It is also possible to create files
+  with a defined size without setting contents.
 
 - It is possible to pause and resume using the fake filesystem, if the
-  real file system has to be used in a test step.
+  real file system has to be used in a test step (see :ref:`pause_resume`).
 
 - ``pyfakefs`` defaults to the OS it is running on, but can also be configured
-  to test code running under another OS (Linux, macOS or Windows).
+  to test code running under another OS (Linux, macOS or Windows, see :ref:`simulate_os`).
 
 - ``pyfakefs`` can be configured to behave as if running as a root or as a
-  non-root user, independently from the actual user.
+  non-root user, independently from the actual user (see :ref:`allow_root_user`).
 
 .. _limitations:
 

docs/usage.rst

@@ -5,6 +5,7 @@ Test Scenarios
 --------------
 There are several approaches for implementing tests using ``pyfakefs``.
 
+.. _pytest_plugin:
 
 Patch using the pytest plugin
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -54,6 +55,8 @@ respectively.
   done in the fake filesystem inside a test will remain there until the respective scope
   ends (see also :ref:`nested_patcher_invocation`).
 
+.. _unittest_usage:
+
 Patch using fake_filesystem_unittest
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 If you are using the Python ``unittest`` package, the easiest approach is to

pyfakefs/fake_file.py

@@ -531,7 +531,7 @@ def add_entry(self, path_object: FakeFile) -> None:
             and not self.filesystem.is_windows_fs
             and not self.has_permission(helpers.PERM_WRITE)
         ):
-            raise OSError(errno.EACCES, "Permission Denied", self.path)
+            self.filesystem.raise_os_error(errno.EACCES, self.path)
 
         path_object_name: str = to_string(path_object.name)
         if path_object_name in self.entries:
@@ -845,7 +845,7 @@ def fileno(self) -> int:
         """Return the file descriptor of the file object."""
         if self.filedes is not None:
             return self.filedes
-        raise OSError(errno.EBADF, "Invalid file descriptor")
+        self._filesystem.raise_os_error(errno.EBADF)
 
     def close(self) -> None:
         """Close the file."""
@@ -1258,7 +1258,7 @@ def fileno(self) -> int:
         """Return the file descriptor of the wrapped standard stream."""
         if self.filedes is not None:
             return self.filedes
-        raise OSError(errno.EBADF, "Invalid file descriptor")
+        raise OSError(errno.EBADF, os.strerror(errno.EBADF))
 
     def read(self, n: int = -1) -> bytes:
         return cast(bytes, self._stream_object.read())
@@ -1313,7 +1313,7 @@ def fileno(self) -> int:
         """Return the file descriptor of the file object."""
         if self.filedes is not None:
             return self.filedes
-        raise OSError(errno.EBADF, "Invalid file descriptor")
+        raise OSError(errno.EBADF, os.strerror(errno.EBADF))
 
     def close(self) -> None:
         """Close the directory."""
@@ -1388,7 +1388,7 @@ def fileno(self) -> int:
         """Return the fake file descriptor of the pipe object."""
         if self.filedes is not None:
             return self.filedes
-        raise OSError(errno.EBADF, "Invalid file descriptor")
+        raise OSError(errno.EBADF, os.strerror(errno.EBADF))
 
     def read(self, numBytes: int = -1) -> bytes:
         """Read from the real pipe."""

pyfakefs/fake_filesystem.py

@@ -488,7 +488,7 @@ def raise_os_error(
             filename: The name of the affected file, if any.
             winerror: Windows only - the specific Windows error code.
         """
-        message = os.strerror(err_no) + " in the fake filesystem"
+        message = os.strerror(err_no)
         if winerror is not None and sys.platform == "win32" and self.is_windows_fs:
             raise OSError(err_no, message, filename, winerror)
         raise OSError(err_no, message, filename)
@@ -1885,7 +1885,7 @@ def lresolve(self, path: AnyPath) -> FakeFile:
         """
         path_str = make_string_path(path)
         if not path_str:
-            raise OSError(errno.ENOENT, path_str)
+            self.raise_os_error(errno.ENOENT, path_str)
         if path_str == matching_string(path_str, self.root.name):
             # The root directory will never be a link
             return self.root
@@ -1915,7 +1915,7 @@ def lresolve(self, path: AnyPath) -> FakeFile:
             )
         except KeyError:
             pass
-        raise OSError(errno.ENOENT, path_str)
+        self.raise_os_error(errno.ENOENT, path_str)
 
     def add_object(self, file_path: AnyStr, file_object: AnyFile) -> None:
         """Add a fake file or directory into the filesystem at file_path.

pyfakefs/fake_os.py

@@ -259,13 +259,13 @@ def open(
             and self.filesystem.exists(path)
             and not self.filesystem.isdir(path)
         ):
-            raise OSError(errno.ENOTDIR, "path is not a directory", path)
+            self.filesystem.raise_os_error(errno.ENOTDIR, path)
 
         has_follow_flag = (
             hasattr(os, "O_NOFOLLOW") and flags & os.O_NOFOLLOW == os.O_NOFOLLOW
         )
         if has_follow_flag and self.filesystem.islink(path):
-            raise OSError(errno.ELOOP, "path is a symlink", path)
+            self.filesystem.raise_os_error(errno.ELOOP, path)
 
         has_tmpfile_flag = (
             hasattr(os, "O_TMPFILE") and flags & os.O_TMPFILE == os.O_TMPFILE
@@ -392,7 +392,7 @@ def lseek(self, fd: int, pos: int, whence: int):
         if isinstance(file_handle, FakeFileWrapper):
             file_handle.seek(pos, whence)
         else:
-            raise OSError(errno.EBADF, "Bad file descriptor for fseek")
+            self.filesystem.raise_os_error(errno.EBADF)
 
     def pipe(self) -> Tuple[int, int]:
         read_fd, write_fd = os.pipe()
@@ -453,13 +453,13 @@ def chdir(self, path: AnyStr) -> None:
             path = self.filesystem.resolve_path(path, allow_fd=True)
         except OSError as exc:
             if self.filesystem.is_macos and exc.errno == errno.EBADF:
-                raise OSError(errno.ENOTDIR, "Not a directory: " + str(path))
+                self.filesystem.raise_os_error(errno.ENOTDIR, str(path))
             elif (
                 self.filesystem.is_windows_fs
                 and exc.errno == errno.ENOENT
                 and path == ""
             ):
-                raise OSError(errno.EINVAL, "Invalid argument:  + str(path)")
+                self.filesystem.raise_os_error(errno.EINVAL, str(path))
             raise
         try:
             self.filesystem.confirmdir(path)
@@ -528,7 +528,7 @@ def getxattr(
             attribute = attribute.decode(sys.getfilesystemencoding())
         file_obj = self.filesystem.resolve(path, follow_symlinks, allow_fd=True)
         if attribute not in file_obj.xattr:
-            raise OSError(errno.ENODATA, "No data available", path)
+            self.filesystem.raise_os_error(errno.ENODATA, path)
         return file_obj.xattr.get(attribute)
 
     def listxattr(
@@ -1026,7 +1026,7 @@ def ftruncate(self, fd: int, length: int) -> None:
         if isinstance(file_object, FakeFileWrapper):
             file_object.size = length
         else:
-            raise OSError(errno.EBADF, "Invalid file descriptor")
+            self.filesystem.raise_os_error(errno.EBADF)
 
     def access(
         self,

pyfakefs/tests/fake_filesystem_shutil_test.py

@@ -212,6 +212,26 @@ def test_copy(self):
         self.assertTrue(os.path.exists(dst_file))
         self.assertEqual(os.stat(src_file).st_mode, os.stat(dst_file).st_mode)
 
+    def test_permission_error_message(self):
+        self.check_posix_only()
+        dst_dir = Path(self.make_path("home1"))
+        src_dir2 = os.path.join(dst_dir, "dir1")
+        os.makedirs(src_dir2)
+        dst_dir.chmod(0o555)
+        src_dir = Path(self.make_path("drive1"))
+        os.makedirs(src_dir)
+        src_file = src_dir / "new.txt"
+        src_file.touch()
+
+        msg = f"[Errno 13] Permission denied: '{dst_dir}'"
+        with self.assertRaises(PermissionError, msg=msg):
+            shutil.copy2(src_file, dst_dir)
+
+        dst_dir2 = dst_dir / "dir2"
+        msg = f"[Errno 13] Permission denied: '{dst_dir2}'"
+        with self.assertRaises(PermissionError, msg=msg):
+            shutil.move(src_dir2, dst_dir2)
+
     def test_copy_directory(self):
         src_file = self.make_path("xyzzy")
         parent_directory = self.make_path("parent")