add tests for appfs

fs/mode.py

@@ -15,11 +15,27 @@
 class Mode(object):
     """
     A mode object provides properties that can be used to interrogate
-    the mode strings used when opening files.
+    the `mode
+    strings <https://docs.python.org/3/library/functions.html#open>`_ used
+    when opening files.
 
-    :param str mode: A *mode* as used by ``open``.
+    :param str mode: A *mode* string, as used by ``io.open``.
     :raises ValueError: If the mode string is invalid.
 
+
+    Here's an example of typical use::
+
+        >>> mode = Mode('rb')
+        >>> mode.reading
+        True
+        >>> mode.writing
+        False
+        >>> mode.binary
+        True
+        >>> mode.text
+        False
+
+
     """
 
     def __init__(self, mode):

fs/osfs.py

@@ -125,7 +125,7 @@ def _make_details_from_stat(cls, stat_result):
             'size': stat_result.st_size,
             'type': int(cls._get_type_from_stat(stat_result))
         }
-        if hasattr(stat, 'st_birthtime'):
+        if hasattr(stat_result, 'st_birthtime'):
             details['created'] = stat_result.st_birthtime
         ctime_key = (
             'created'