Change test_invalid_chars to call the base version first (eliminates duplicate code)

fs/tests/test_fs.py

@@ -31,11 +31,7 @@ class TestOSFS(unittest.TestCase,FSTestCases,ThreadingTestCases):
         return os.path.exists(os.path.join(self.temp_dir, relpath(p)))
 
     def test_invalid_chars(self):
-        self.assertEqual(self.fs.validatepath(''), None)
-        self.assertEqual(self.fs.validatepath('.foo'), None)
-        self.assertEqual(self.fs.validatepath('foo'), None)
-        self.assertEqual(self.fs.validatepath('foo/bar'), None)
-        self.assert_(self.fs.isvalidpath('foo/bar'))
+        super(TestOSFS, self).test_invalid_chars()
 
         self.assertRaises(errors.InvalidCharsInPathError, self.fs.open, 'invalid\0file', 'wb')
         self.assertFalse(self.fs.isvalidpath('invalid\0file'))