Raise OSError in os.readlink if path ends with separator

- fixes pytest-dev#359

CHANGES.md

@@ -8,6 +8,8 @@ The release versions are PyPi releases.
 #### Infrastructure
 
 #### Fixes
+  * `os.readlink` shall raise under Posix if the argument ends with a path 
+    separator ([#359](../../issues/359))
 
 ## [Version 3.4.1](https://pypi.python.org/pypi/pyfakefs/3.4.1)
 
@@ -39,8 +41,9 @@ must use pyfakefs 3.3 or earlier.
   start with the message issued in the real file system in Unix systems (see [#202](../../issues/202))
 
 #### Infrastructure
-  * Changed API to be PEP-8 conform [#186](../../issues/186). Note: The old API is still available.
-  * Removed Python 2.6 support [#293](../../issues/293)
+  * Changed API to be PEP-8 conform ([#186](../../issues/186)). Note: The old
+    API is still available.
+  * Removed Python 2.6 support ([#293](../../issues/293))
   * Added usage documentation to GitHub Pages
   * Added contributing guide
   * Added flake8 tests to Travis CI

pyfakefs/fake_filesystem.py

@@ -2483,7 +2483,8 @@ def readlink(self, path):
         Raises:
             TypeError: if path is None
             OSError: (with errno=ENOENT) if path is not a valid path, or
-                (with errno=EINVAL) if path is valid, but is not a symlink.
+                (with errno=EINVAL) if path is valid, but is not a symlink,
+                or if the path ends with a path separator (Posix only)
         """
         if path is None:
             raise TypeError
@@ -2493,6 +2494,9 @@ def readlink(self, path):
             self.raise_os_error(exc.errno, path)
         if S_IFMT(link_obj.st_mode) != S_IFLNK:
             self.raise_os_error(errno.EINVAL, path)
+        if not self.is_windows_fs and path.endswith(self.path_separator):
+            self.raise_os_error(errno.EINVAL, path)
+
         return link_obj.contents
 
     def makedir(self, dir_name, mode=PERM_DEF):

tests/fake_os_test.py

@@ -55,14 +55,6 @@ def setUp(self):
         self.rwx = self.os.R_OK | self.os.W_OK | self.os.X_OK
         self.rw = self.os.R_OK | self.os.W_OK
 
-    def test_359(self):
-        component1 = ""
-        path0 = self.make_path('alpha')
-        self.os.symlink(self.base_path, path0)
-        path0 = self.os.path.join(path0, component1)
-        result = self.os.readlink(path0)
-        print(result)
-
     def test_chdir(self):
         """chdir should work on a directory."""
         directory = self.make_path('foo')
@@ -349,6 +341,22 @@ def test_lstat_trailing_sep(self):
         self.assertEqual(stat, self.os.lstat(
             self.base_path + self.path_separator() + self.path_separator()))
 
+    def test_link_ending_with_sep_posix(self):
+        # regression test for #359
+        self.check_posix_only()
+        link_path = self.make_path('foo')
+        self.os.symlink(self.base_path, link_path)
+        self.assert_raises_os_error(errno.EINVAL,
+                                    self.os.readlink, link_path + self.os.sep)
+
+    def test_link_ending_with_sep_windows(self):
+        self.check_windows_only()
+        self.skip_if_symlink_not_supported()
+        link_path = self.make_path('foo')
+        self.os.symlink(self.base_path, link_path)
+        self.assertEqual(self.base_path,
+                         self.os.readlink(link_path + self.os.sep))
+
     @unittest.skipIf(sys.version_info < (3, 3),
                      'file descriptor as path new in Python 3.3')
     def test_lstat_uses_open_fd_as_path(self):