add function to clear the handler..

wsfwd/__init__.py

@@ -222,6 +222,13 @@ class WSFWDCommon:
 		# XXX - make sure we don't overwrite an existing one
 		self._procmsgs[stream] = hndlr
 
+	def clear_stream_handler(self, stream):
+		'''
+		Clear the handler for stream.
+		'''
+
+		del self._procmsgs[stream]
+
 	async def _process_msgs(self):
 		'''
 		Internal routine to dispatch messages received via
@@ -625,6 +632,9 @@ class Test(unittest.IsolatedAsyncioTestCase):
 				await self.drain(stream)
 
 			async def handle_exec(self, msg):
+				self.add_stream_handler(msg['stdin'], None)
+				self.clear_stream_handler(msg['stdin'])
+				assert msg['stdin'] not in self._procmsgs
 				self.add_stream_handler(msg['stdin'],
 				    functools.partial(self.echo_handler,
 				    msg['stdout']))