refactor: raise new instances for PortNotOpenError and SerialTimeoutException

related to #502
fixes #437
diff --git a/test/handlers/protocol_test.py b/test/handlers/protocol_test.py
index f2e572f..c0cffa6 100644
--- a/test/handlers/protocol_test.py
+++ b/test/handlers/protocol_test.py
@@ -80,7 +80,7 @@
 
     def inWaiting(self):
         """Return the number of characters currently in the input buffer."""
-        if not self._isOpen: raise portNotOpenError
+        if not self._isOpen: raise PortNotOpenError()
         if self.logger:
             # set this one to debug as the function could be called often...
             self.logger.debug('WARNING: inWaiting returns dummy value')
@@ -90,7 +90,7 @@
         """Read size bytes from the serial port. If a timeout is set it may
         return less characters as requested. With no timeout it will block
         until the requested number of bytes is read."""
-        if not self._isOpen: raise portNotOpenError
+        if not self._isOpen: raise PortNotOpenError()
         data = '123' # dummy data
         return bytes(data)
 
@@ -98,73 +98,73 @@
         """Output the given string over the serial port. Can block if the
         connection is blocked. May raise SerialException if the connection is
         closed."""
-        if not self._isOpen: raise portNotOpenError
+        if not self._isOpen: raise PortNotOpenError()
         # nothing done
         return len(data)
 
     def flushInput(self):
         """Clear input buffer, discarding all that is in the buffer."""
-        if not self._isOpen: raise portNotOpenError
+        if not self._isOpen: raise PortNotOpenError()
         if self.logger:
             self.logger.info('ignored flushInput')
 
     def flushOutput(self):
         """Clear output buffer, aborting the current output and
         discarding all that is in the buffer."""
-        if not self._isOpen: raise portNotOpenError
+        if not self._isOpen: raise PortNotOpenError()
         if self.logger:
             self.logger.info('ignored flushOutput')
 
     def sendBreak(self, duration=0.25):
         """Send break condition. Timed, returns to idle state after given
         duration."""
-        if not self._isOpen: raise portNotOpenError
+        if not self._isOpen: raise PortNotOpenError()
         if self.logger:
             self.logger.info('ignored sendBreak({!r})'.format(duration))
 
     def setBreak(self, level=True):
         """Set break: Controls TXD. When active, to transmitting is
         possible."""
-        if not self._isOpen: raise portNotOpenError
+        if not self._isOpen: raise PortNotOpenError()
         if self.logger:
             self.logger.info('ignored setBreak({!r})'.format(level))
 
     def setRTS(self, level=True):
         """Set terminal status line: Request To Send"""
-        if not self._isOpen: raise portNotOpenError
+        if not self._isOpen: raise PortNotOpenError()
         if self.logger:
             self.logger.info('ignored setRTS({!r})'.format(level))
 
     def setDTR(self, level=True):
         """Set terminal status line: Data Terminal Ready"""
-        if not self._isOpen: raise portNotOpenError
+        if not self._isOpen: raise PortNotOpenError()
         if self.logger:
             self.logger.info('ignored setDTR({!r})'.format(level))
 
     def getCTS(self):
         """Read terminal status line: Clear To Send"""
-        if not self._isOpen: raise portNotOpenError
+        if not self._isOpen: raise PortNotOpenError()
         if self.logger:
             self.logger.info('returning dummy for getCTS()')
         return True
 
     def getDSR(self):
         """Read terminal status line: Data Set Ready"""
-        if not self._isOpen: raise portNotOpenError
+        if not self._isOpen: raise PortNotOpenError()
         if self.logger:
             self.logger.info('returning dummy for getDSR()')
         return True
 
     def getRI(self):
         """Read terminal status line: Ring Indicator"""
-        if not self._isOpen: raise portNotOpenError
+        if not self._isOpen: raise PortNotOpenError()
         if self.logger:
             self.logger.info('returning dummy for getRI()')
         return False
 
     def getCD(self):
         """Read terminal status line: Carrier Detect"""
-        if not self._isOpen: raise portNotOpenError
+        if not self._isOpen: raise PortNotOpenError()
         if self.logger:
             self.logger.info('returning dummy for getCD()')
         return True