Fix handling of missing attribute in os.getxattr

- no tests for real OS (extended atributes not enabled in CI)
- fixes #971

Author: mrbean-bremen

CHANGES.md

@@ -22,6 +22,7 @@ The released versions correspond to PyPI releases.
   (see [#965](../../issues/965))
 * fixed handling of `dirfd` in `os.symlink` (see [#968](../../issues/968))
 * add missing `follow_symlink` argument to `os.link` (see [#973](../../issues/973))
+* fixed handling of missing attribute in `os.getxattr` (see [#971](../../issues/971))
 
 ### Enhancements
 * added support for `O_NOFOLLOW` and `O_DIRECTORY` flags in `os.open`

README.md

@@ -120,7 +120,7 @@ for more information.
 pyfakefs.py was initially developed at Google by Mike Bland as a modest fake
 implementation of core Python modules.  It was introduced to all of Google
 in September 2006. Since then, it has been enhanced to extend its
-functionality and usefulness.  At last count, pyfakefs was used in over 2,000
+functionality and usefulness.  At last count, pyfakefs was used in over 20,000
 Python tests at Google.
 
 Google released pyfakefs to the public in 2011 as Google Code project

docs/usage.rst

@@ -690,7 +690,7 @@ While ``pyfakefs`` can be used just with the standard Python file system
 functions, there are a few convenience methods in ``fake_filesystem`` that can
 help you setting up your tests. The methods can be accessed via the
 ``fake_filesystem`` instance in your tests: ``Patcher.fs``, the ``fs``
-fixture in pytest, ``TestCase.fs`` for ``unittest``, and the ``fs`` argument
+fixture in pytest, ``TestCase.fs`` for ``unittest``, and the positional argument
 for the ``patchfs`` decorator.
 
 File creation helpers
@@ -965,6 +965,10 @@ The following test works both under Windows and Linux:
       assert os.path.splitdrive(r"C:\foo\bar") == ("C:", r"\foo\bar")
       assert os.path.ismount("C:")
 
+.. note:: Only behavior not relying on OS-specific functionality is emulated on another system.
+  For example, if you use the Linux-specific functionality of extended attributes (``os.getxattr`` etc.)
+  in your code, you have to test this under Linux.
+
 Set file as inaccessible under Windows
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Normally, if you try to set a file or directory as inaccessible using ``chmod`` under

pyfakefs/fake_os.py

@@ -491,6 +491,8 @@ def getxattr(
         if isinstance(attribute, bytes):
             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)
         return file_obj.xattr.get(attribute)
 
     def listxattr(

pyfakefs/tests/fake_os_test.py

@@ -5496,26 +5496,25 @@ def test_empty_xattr(self):
         self.assertEqual([], self.os.listxattr(self.dir_path))
         self.assertEqual([], self.os.listxattr(self.file_path))
 
+    def test_getxattr_raises_for_non_existing_file(self):
+        with self.assertRaises(FileNotFoundError):
+            self.os.getxattr("bogus_path", "test")
+
+    def test_getxattr_raises_for_non_existing_attribute(self):
+        with self.assertRaises(OSError) as cm:
+            self.os.getxattr(self.file_path, "bogus")
+        self.assertEqual(errno.ENODATA, cm.exception.errno)
+
     def test_setxattr(self):
-        self.assertRaises(TypeError, self.os.setxattr, self.file_path, "test", "value")
-        self.assert_raises_os_error(
-            errno.EEXIST,
-            self.os.setxattr,
-            self.file_path,
-            "test",
-            b"value",
-            self.os.XATTR_REPLACE,
-        )
+        with self.assertRaises(TypeError):
+            self.os.setxattr(self.file_path, "test", "value")
+        with self.assertRaises(FileExistsError):
+            self.os.setxattr(self.file_path, "test", b"value", self.os.XATTR_REPLACE)
         self.os.setxattr(self.file_path, "test", b"value")
         self.assertEqual(b"value", self.os.getxattr(self.file_path, "test"))
-        self.assert_raises_os_error(
-            errno.ENODATA,
-            self.os.setxattr,
-            self.file_path,
-            "test",
-            b"value",
-            self.os.XATTR_CREATE,
-        )
+        with self.assertRaises(OSError) as cm:
+            self.os.setxattr(self.file_path, "test", b"value", self.os.XATTR_CREATE)
+        self.assertEqual(errno.ENODATA, cm.exception.errno)
 
     def test_removeattr(self):
         self.os.removexattr(self.file_path, "test")
@@ -5525,7 +5524,9 @@ def test_removeattr(self):
         self.assertEqual(b"value", self.os.getxattr(self.file_path, "test"))
         self.os.removexattr(self.file_path, "test")
         self.assertEqual([], self.os.listxattr(self.file_path))
-        self.assertIsNone(self.os.getxattr(self.file_path, "test"))
+        with self.assertRaises(OSError) as cm:
+            self.os.getxattr(self.file_path, "test")
+        self.assertEqual(errno.ENODATA, cm.exception.errno)
 
     def test_default_path(self):
         self.os.chdir(self.dir_path)