Fix test_open_on_directory for SFTPFS

fs/expose/dokan/__init__.py

@@ -49,8 +49,6 @@ systems with Dokan installed.
 #  All rights reserved; available under the terms of the MIT License.
 
 import sys
-if sys.platform != "win32":
-    raise ImportError("Dokan is only available on win32")
 
 import os
 import signal
@@ -61,9 +59,6 @@ import subprocess
 import pickle
 import datetime
 import ctypes
-from ctypes.wintypes import LPCWSTR, WCHAR
-
-kernel32 = ctypes.windll.kernel32
 
 from fs.base import threading
 from fs.errors import *
@@ -72,13 +67,14 @@ from fs.local_functools import wraps
 
 try:
     import libdokan
-except (NotImplementedError,EnvironmentError,ImportError):
+except (NotImplementedError,EnvironmentError,ImportError,NameError,):
     is_available = False
     sys.modules.pop("fs.expose.dokan.libdokan",None)
     libdokan = None
 else:
     is_available = True
-
+    from ctypes.wintypes import LPCWSTR, WCHAR
+    kernel32 = ctypes.windll.kernel32
 
 #  Options controlling the behaiour of the Dokan filesystem
 DOKAN_OPTION_DEBUG = 1

fs/sftpfs.py

@@ -136,12 +136,12 @@ class SFTPFS(FS):
     @convert_os_errors
     def open(self,path,mode="r",bufsize=-1):
         npath = self._normpath(path)
-        #  paramiko implements its own buffering and write-back logic,
-        #  so we don't need to use a RemoteFileBuffer here.
-        f = self.client.open(npath,mode,bufsize)
         if self.isdir(path):
             msg = "that's a directory: %(path)s"
             raise ResourceInvalidError(path,msg=msg)
+        #  paramiko implements its own buffering and write-back logic,
+        #  so we don't need to use a RemoteFileBuffer here.
+        f = self.client.open(npath,mode,bufsize)
         return f
 
     @convert_os_errors

fs/tests/__init__.py

@@ -70,7 +70,15 @@ class FSTestCases(object):
 
     def test_open_on_directory(self):
         self.fs.makedir("testdir")
-        self.assertRaises(ResourceInvalidError,self.fs.open,"testdir")
+        try:
+            self.fs.open("testdir")
+        except ResourceInvalidError:
+            pass
+        except Exception:
+            ecls = sys.exc_info[0]
+            assert False, "%s raised instead of ResourceInvalidError" % (ecls,)
+        else:
+            assert False, "ResourceInvalidError was not raised"
       
     def test_writefile(self):
         self.assertRaises(ResourceNotFoundError,self.fs.open,"test1.txt")