PYTHON-2718 Test redaction of security sensitive command monitoring events (#637)

(cherry picked from commit 59dc6d8)

Author: prashantmital

pymongo/monitoring.py

@@ -498,6 +498,15 @@ def register(listener):
      "updateuser", "copydbgetnonce", "copydbsaslstart", "copydb"])
 
 
+# The "hello" command is also deemed sensitive when attempting speculative
+# authentication.
+def _is_speculative_authenticate(command_name, doc):
+    if (command_name.lower() in ('hello', 'ismaster') and
+            'speculativeAuthenticate' in doc):
+        return True
+    return False
+
+
 class _CommandEvent(object):
     """Base class for command events."""
 
@@ -564,7 +573,9 @@ def __init__(self, command, database_name, request_id, connection_id,
         super(CommandStartedEvent, self).__init__(
             command_name, request_id, connection_id, operation_id,
             service_id=service_id)
-        if command_name.lower() in _SENSITIVE_COMMANDS:
+        cmd_name, cmd_doc = command_name.lower(), command[command_name]
+        if (cmd_name in _SENSITIVE_COMMANDS or
+                _is_speculative_authenticate(cmd_name, command)):
             self.__cmd = {}
         else:
             self.__cmd = command
@@ -610,7 +621,9 @@ def __init__(self, duration, reply, command_name,
             command_name, request_id, connection_id, operation_id,
             service_id=service_id)
         self.__duration_micros = _to_micros(duration)
-        if command_name.lower() in _SENSITIVE_COMMANDS:
+        cmd_name = command_name.lower()
+        if (cmd_name in _SENSITIVE_COMMANDS or
+                _is_speculative_authenticate(cmd_name, reply)):
             self.__reply = {}
         else:
             self.__reply = reply