fix deprecated function, unicode in test
diff --git a/serial/serialutil.py b/serial/serialutil.py
index 1ccfabb..5fb5588 100644
--- a/serial/serialutil.py
+++ b/serial/serialutil.py
@@ -564,7 +564,7 @@
         self.apply_settings(d)
 
     def isOpen(self):
-        return self._is_open
+        return self.is_open
 
     #  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -
     # additional functionality