fix test

Author: Carreau

ipykernel/iostream.py

@@ -14,6 +14,7 @@
 from weakref import WeakSet
 import traceback
 from io import StringIO, TextIOBase
+import io
 import os
 
 import zmq
@@ -295,7 +296,7 @@ def fileno(self):
         if getattr(self, '_original_stdstream_copy', None) is not None:
             return self._original_stdstream_copy
         else:
-            raise UnsupportedOperation('fileno')
+            raise io.UnsupportedOperation("fileno")
 
     def _watch_pipe_fd(self):
         """