Check for both os.path.sep and os.path.altsep

When normalizing paths, we want to handle the following cases:

- Someone is using a Windows-style path on Windows
- Someone is using a Unix style path on Unix
- Someone is using a Unix style path on Windows

os.path.sep will handle the native directory separator character while
os.path.altsep (when set) will handle alternate separators. Further,
os.path.abspath does the right thing on Windows when handed a Unix-style
path.

Related to #175

1 files changed, 7 insertions, 4 deletions

diff --git a/src/flake8/utils.py b/src/flake8/utils.py
index 7f31f8f..f432dac 100644
--- a/src/flake8/utils.py
+++ b/src/flake8/utils.py
@@ -53,12 +53,15 @@ def normalize_path(path, parent=os.curdir):
     :rtype:
         str
     """
-    # NOTE(sigmavirus24): Using os.path.sep allows for Windows paths to
-    # be specified and work appropriately.
+    # NOTE(sigmavirus24): Using os.path.sep and os.path.altsep allow for
+    # Windows compatibility with both Windows-style paths (c:\\foo\bar) and
+    # Unix style paths (/foo/bar).
     separator = os.path.sep
-    if separator in path:
+    # NOTE(sigmavirus24): os.path.altsep may be None
+    alternate_separator = os.path.altsep or ''
+    if separator in path or alternate_separator in path:
         path = os.path.abspath(os.path.join(parent, path))
-    return path.rstrip(separator)
+    return path.rstrip(separator + alternate_separator)
 
 
 def stdin_get_value():