Fix os.file for unreadable files

- set regular file mode if none set in FakeFile st_mode arg
- add convenience permission argument to create_file()
- fixes #588

Author: mrbean-bremen

CHANGES.md

@@ -2,7 +2,7 @@
 The released versions correspond to PyPi releases.
 
 ## Version 4.4.0 (as yet unreleased)
-
+  
 #### New Features
   * added support for `pathlib.Path.link_to` (new in Python 3.8) 
     (see [#580](../../issues/580))
@@ -16,7 +16,9 @@ The released versions correspond to PyPi releases.
     (see [#581](../../issues/581))
   * added non-functional argument `effective_ids` to `os.access`
     (see [#585](../../issues/585))
-      
+  * correctly handle `os.file` for unreadable files
+    (see [#588](../../issues/588))
+
 ### Infrastructure
   * added automatic documentation build and check-in
 

pyfakefs/fake_filesystem.py

@@ -269,7 +269,9 @@ def __init__(self, name, st_mode=S_IFREG | PERM_DEF_FILE,
         Args:
             name: Name of the file/directory, without parent path information
             st_mode: The stat.S_IF* constant representing the file type (i.e.
-                stat.S_IFREG, stat.S_IFDIR)
+                stat.S_IFREG, stat.S_IFDIR), and the file permissions.
+                If no file type is set (e.g. permission flags only), a
+                regular file type is assumed.
             contents: The contents of the filesystem object; should be a string
                 or byte object for regular files, and a list of other
                 FakeFile or FakeDirectory objects for FakeDirectory objects
@@ -288,6 +290,8 @@ def __init__(self, name, st_mode=S_IFREG | PERM_DEF_FILE,
         self.name = name
         self.stat_result = FakeStatResult(
             filesystem.is_windows_fs, USER_ID, GROUP_ID, time.time())
+        if st_mode >> 12 == 0:
+            st_mode |= S_IFREG
         self.stat_result.st_mode = st_mode
         self.encoding = encoding
         self.errors = errors or 'strict'
@@ -2906,14 +2910,17 @@ def makedirs(self, dir_name, mode=PERM_DEF, exist_ok=False):
                     e.errno = errno.ENOENT
                 self.raise_os_error(e.errno, e.filename)
 
-    def _is_of_type(self, path, st_flag, follow_symlinks=True):
+    def _is_of_type(self, path, st_flag, follow_symlinks=True,
+                    check_read_perm=True):
         """Helper function to implement isdir(), islink(), etc.
 
         See the stat(2) man page for valid stat.S_I* flag values
 
         Args:
             path: Path to file to stat and test
             st_flag: The stat.S_I* flag checked for the file's st_mode
+            check_read_perm: If True (default) False is returned for
+                existing but unreadable file paths.
 
         Returns:
             (boolean) `True` if the st_flag is set in path's st_mode.
@@ -2925,7 +2932,8 @@ def _is_of_type(self, path, st_flag, follow_symlinks=True):
         if path is None:
             raise TypeError
         try:
-            obj = self.resolve(path, follow_symlinks)
+            obj = self.resolve(path, follow_symlinks,
+                               check_read_perm=check_read_perm)
             if obj:
                 self.raise_for_filepath_ending_with_separator(
                     path, obj, macos_handling=not follow_symlinks)
@@ -2960,7 +2968,8 @@ def isfile(self, path, follow_symlinks=True):
         Raises:
             TypeError: if path is None.
         """
-        return self._is_of_type(path, S_IFREG, follow_symlinks)
+        return self._is_of_type(path, S_IFREG, follow_symlinks,
+                                check_read_perm=False)
 
     def islink(self, path):
         """Determine if path identifies a symbolic link.

pyfakefs/tests/fake_os_test.py

@@ -547,6 +547,11 @@ def test_isfile_with_trailing_separator_macos(self):
         self.create_file(file_path)
         self.assertFalse(self.os.path.isfile(file_path + self.os.sep))
 
+    def test_isfile_not_readable_file(self):
+        file_path = self.make_path('foo')
+        self.create_file(file_path, perm=0)
+        self.assertTrue(self.os.path.isfile(file_path))
+
     def check_stat_with_trailing_separator(self, error_nr):
         # regression test for #376
         file_path = self.make_path('foo')

pyfakefs/tests/fake_pathlib_test.py

@@ -879,6 +879,12 @@ def test_isfile(self):
         self.assertEqual(self.os.path.isfile(path),
                          self.os.path.isfile(self.path(path)))
 
+    def test_isfile_not_readable(self):
+        path = self.make_path('foo', 'bar', 'baz')
+        self.create_file(path, perm=0)
+        self.assertEqual(self.os.path.isfile(path),
+                         self.os.path.isfile(self.path(path)))
+
     def test_islink(self):
         path = self.make_path('foo', 'bar', 'baz')
         self.create_file(path)

pyfakefs/tests/test_utils.py

@@ -295,7 +295,7 @@ def create_dir(self, dir_path):
             self.os.mkdir(existing_path)
             self.os.chmod(existing_path, 0o777)
 
-    def create_file(self, file_path, contents=None, encoding=None):
+    def create_file(self, file_path, contents=None, encoding=None, perm=0o666):
         """Create the given file at `file_path` with optional contents,
         including subdirectories. `file_path` shall be composed using
         `make_path()`.
@@ -309,7 +309,7 @@ def create_file(self, file_path, contents=None, encoding=None):
         with self.open(file_path, mode) as f:
             if contents is not None:
                 f.write(contents)
-        self.os.chmod(file_path, 0o666)
+        self.os.chmod(file_path, perm)
 
     def create_symlink(self, link_path, target_path):
         """Create the path at `link_path`, and a symlink to this path at