Fixed handling of current path in lresolve() / os.lstat()

- fixes #516
- back-ported from master

Author: mrbean-bremen

Diff for: CHANGES.md

@@ -12,6 +12,8 @@ the proposed changes so you can be ready.
 This version backports some fixes from master.
 
 #### Fixes
+  * Fixed handling of relative paths in `lresolve` / `os.lstat`
+    (see [#516](../../issues/516))
   * Fixed `os.walk` if path ends with path separator
     (see [#512](../../issues/512))
   * Fixed handling of empty path in `os.makedirs`

Diff for: pyfakefs/fake_filesystem.py

@@ -1511,6 +1511,8 @@ def absnormpath(self, path):
         cwd = self._matching_string(path, self.cwd)
         if not path:
             path = self.path_separator
+        if path == self._matching_string(path, '.'):
+            path = cwd
         elif not self._starts_with_root_path(path):
             # Prefix relative paths with cwd, if cwd is not root.
             root_name = self._matching_string(path, self.root.name)
@@ -2082,12 +2084,16 @@ def lresolve(self, path):
             IOError: if the object is not found.
         """
         path = make_string_path(path)
+        if not path:
+            raise OSError(errno.ENOENT, path)
         if path == self.root.name:
             # The root directory will never be a link
             return self.root
 
         # remove trailing separator
         path = self._path_without_trailing_separators(path)
+        if path == self._matching_string(path, '.'):
+            path = self.cwd
         path = self._original_path(path)
 
         parent_directory, child_name = self.splitpath(path)
@@ -2102,7 +2108,8 @@ def lresolve(self, path):
                 self.raise_io_error(errno.ENOENT, path)
             if not parent_obj.st_mode & PERM_READ:
                 self.raise_os_error(errno.EACCES, parent_directory)
-            return parent_obj.get_entry(child_name)
+            return (parent_obj.get_entry(child_name) if child_name
+                    else parent_obj)
         except KeyError:
             self.raise_io_error(errno.ENOENT, path)
 

Diff for: pyfakefs/tests/fake_filesystem_vs_real_test.py

@@ -172,7 +172,11 @@ def _compare_behaviors(self, method_name, path, real, fake,
         # pylint: disable=C6403
 
         def _error_class(exc):
-            return (exc and exc.__class__.__name__) or 'None'
+            if exc:
+                if hasattr(exc, 'errno'):
+                    return '{}({})'.format(exc.__class__.__name__, exc.errno)
+                return exc.__class__.__name__
+            return 'None'
 
         real_err, real_value = self._get_real_value(method_name, path, real)
         fake_err, fake_value = self._get_fake_value(method_name, path, fake)

Diff for: pyfakefs/tests/fake_os_test.py

@@ -350,6 +350,24 @@ def test_lstat_trailing_sep(self):
         self.assertEqual(stat, self.os.lstat(
             self.base_path + self.path_separator() + self.path_separator()))
 
+    def test_stat_with_byte_string(self):
+        stat_str = self.os.stat(self.base_path)
+        base_path_bytes = self.base_path.encode('utf8')
+        stat_bytes = self.os.stat(base_path_bytes)
+        self.assertEqual(stat_bytes, stat_str)
+
+    def test_lstat_with_byte_string(self):
+        stat_str = self.os.lstat(self.base_path)
+        base_path_bytes = self.base_path.encode('utf8')
+        stat_bytes = self.os.lstat(base_path_bytes)
+        self.assertEqual(stat_bytes, stat_str)
+
+    def test_stat_with_current_dir(self):
+        # regression test for #516
+        stat_result = self.os.stat('.')
+        lstat_result = self.os.lstat('.')
+        self.assertEqual(stat_result, lstat_result)
+
     def test_exists_with_trailing_sep(self):
         # regression test for #364
         file_path = self.make_path('alpha')
@@ -362,6 +380,11 @@ def test_mkdir_with_trailing_sep(self):
         self.os.mkdir(dir_path + self.os.sep + self.os.sep)
         self.assertTrue(self.os.path.exists(dir_path))
 
+    def test_readlink_empty_path(self):
+        self.check_posix_only()
+        self.assert_raises_os_error(errno.ENOENT,
+                                    self.os.readlink, '')
+
     def test_readlink_ending_with_sep_posix(self):
         # regression test for #359
         self.check_posix_only()