hook-list are updated to accept a sender argument (microsoft#1799)

* hook-list are updated to accept a sender argument

* Update the hook function Signature & add assertions for Sender

autogen/agentchat/conversable_agent.py

@@ -552,7 +552,7 @@ def _process_message_before_send(
         """Process the message before sending it to the recipient."""
         hook_list = self.hook_lists["process_message_before_send"]
         for hook in hook_list:
-            message = hook(message, recipient, silent)
+            message = hook(sender=self, message=message, recipient=recipient, silent=silent)
         return message
 
     def send(

test/agentchat/test_conversable_agent.py

@@ -1087,9 +1087,11 @@ def test_max_turn():
 def test_process_before_send():
     print_mock = unittest.mock.MagicMock()
 
-    def send_to_frontend(message, recipient, silent):
+    # Updated to include sender parameter
+    def send_to_frontend(sender, message, recipient, silent):
+        assert sender.name == "dummy_agent_1", "Sender is not the expected agent"
         if not silent:
-            print(f"Message sent to {recipient.name}: {message}")
+            print(f"Message sent from {sender.name} to {recipient.name}: {message}")
             print_mock(message=message)
         return message