Partial fix for 960 (#963)

* Partial fix for 960

* Fixed a missing = None

* Added test coverage.

autogen/agentchat/groupchat.py

@@ -64,8 +64,10 @@ def agent_by_name(self, name: str) -> Agent:
         """Returns the agent with a given name."""
         return self.agents[self.agent_names.index(name)]
 
-    def next_agent(self, agent: Agent, agents: List[Agent]) -> Agent:
+    def next_agent(self, agent: Agent, agents: Optional[List[Agent]] = None) -> Agent:
         """Return the next agent in the list."""
+        if agents is None:
+            agents = self.agents
 
         # What index is the agent? (-1 if not present)
         idx = self.agent_names.index(agent.name) if agent.name in self.agent_names else -1
@@ -79,20 +81,26 @@ def next_agent(self, agent: Agent, agents: List[Agent]) -> Agent:
                 if self.agents[(offset + i) % len(self.agents)] in agents:
                     return self.agents[(offset + i) % len(self.agents)]
 
-    def select_speaker_msg(self, agents: List[Agent]) -> str:
+    def select_speaker_msg(self, agents: Optional[List[Agent]] = None) -> str:
         """Return the system message for selecting the next speaker. This is always the *first* message in the context."""
+        if agents is None:
+            agents = self.agents
         return f"""You are in a role play game. The following roles are available:
 {self._participant_roles(agents)}.
 
 Read the following conversation.
 Then select the next role from {[agent.name for agent in agents]} to play. Only return the role."""
 
-    def select_speaker_prompt(self, agents: List[Agent]) -> str:
+    def select_speaker_prompt(self, agents: Optional[List[Agent]] = None) -> str:
         """Return the floating system prompt selecting the next speaker. This is always the *last* message in the context."""
+        if agents is None:
+            agents = self.agents
         return f"Read the above conversation. Then select the next role from {[agent.name for agent in agents]} to play. Only return the role."
 
-    def manual_select_speaker(self, agents: List[Agent]) -> Union[Agent, None]:
+    def manual_select_speaker(self, agents: Optional[List[Agent]] = None) -> Union[Agent, None]:
         """Manually select the next speaker."""
+        if agents is None:
+            agents = self.agents
 
         print("Please select the next speaker from the following list:")
         _n_agents = len(agents)

test/agentchat/test_groupchat.py

@@ -421,6 +421,10 @@ def test_next_agent():
     assert groupchat.next_agent(agent2, [agent1, agent2, agent3]) == agent3
     assert groupchat.next_agent(agent3, [agent1, agent2, agent3]) == agent1
 
+    assert groupchat.next_agent(agent1) == agent2
+    assert groupchat.next_agent(agent2) == agent3
+    assert groupchat.next_agent(agent3) == agent1
+
     assert groupchat.next_agent(agent1, [agent1, agent3]) == agent3
     assert groupchat.next_agent(agent3, [agent1, agent3]) == agent1
 
@@ -429,6 +433,48 @@ def test_next_agent():
     assert groupchat.next_agent(agent4, [agent1, agent2, agent3]) == agent1
 
 
+def test_selection_helpers():
+    agent1 = autogen.ConversableAgent(
+        "alice",
+        max_consecutive_auto_reply=10,
+        human_input_mode="NEVER",
+        llm_config=False,
+        default_auto_reply="This is alice speaking.",
+        description="Alice is an AI agent.",
+    )
+    agent2 = autogen.ConversableAgent(
+        "bob",
+        max_consecutive_auto_reply=10,
+        human_input_mode="NEVER",
+        llm_config=False,
+        description="Bob is an AI agent.",
+    )
+    agent3 = autogen.ConversableAgent(
+        "sam",
+        max_consecutive_auto_reply=10,
+        human_input_mode="NEVER",
+        llm_config=False,
+        default_auto_reply="This is sam speaking.",
+        system_message="Sam is an AI agent.",
+    )
+
+    # Test empty is_termination_msg function
+    groupchat = autogen.GroupChat(
+        agents=[agent1, agent2, agent3], messages=[], speaker_selection_method="round_robin", max_round=10
+    )
+
+    select_speaker_msg = groupchat.select_speaker_msg()
+    select_speaker_prompt = groupchat.select_speaker_prompt()
+
+    assert "Alice is an AI agent." in select_speaker_msg
+    assert "Bob is an AI agent." in select_speaker_msg
+    assert "Sam is an AI agent." in select_speaker_msg
+    assert str(["Alice", "Bob", "Sam"]).lower() in select_speaker_prompt.lower()
+
+    with mock.patch.object(builtins, "input", lambda _: "1"):
+        groupchat.manual_select_speaker()
+
+
 if __name__ == "__main__":
     # test_func_call_groupchat()
     # test_broadcast()