ZMQHistoryManager made to work with testing KernelClient which has no history method

IPython/terminal/console/zmqhistory.py

@@ -45,10 +45,12 b' class ZMQHistoryManager(HistoryAccessorBase):'
         Load the history over ZMQ from the kernel. Wraps the history
         messaging with loop to wait to get history results.
         """
+        history = []
+        if hasattr(self.client, "history"):
+            ## In tests, KernelClient may not have a history method
         msg_id = self.client.history(raw=raw, output=output, 
                                      hist_access_type=hist_access_type, 
                                      **kwargs)
-        history = []
         while True:
             try:
                 reply = self.client.get_shell_msg(timeout=1)