Validate llm_config passed to ConversableAgent

Based on #1522, this commit implements the additional validation checks in
`ConversableAgent.`

Add the following validation and `raise ValueError` if:

 - The `llm_config` is `None` (validated in `ConversableAgent`).
 - The `llm_config` has no `model` specified and `config_list` is empty
   (validated in `OpenAIWrapper`).
 - The `config_list` has at least one entry, but not all the entries have
   the `model` is specified (validated in `OpenAIWrapper`).

The rest of the changes are code churn to adjust or add the test cases.

autogen/agentchat/conversable_agent.py

@@ -136,31 +136,18 @@ def __init__(
             else (lambda x: content_str(x.get("content")) == "TERMINATE")
         )
 
-        if llm_config is None:
-            raise ValueError("Please specify the value for 'llm_config'.")
-
-        if isinstance(llm_config, dict):
-            config_list = None
-            if "config_list" in llm_config:
-                config_list = llm_config["config_list"]
-            if config_list is None or len(config_list) == 0:
-                raise ValueError("Please specify at least one configuration in 'llm_config'.")
-
-            # We know that there's at least one entry in the configuration.
-            # Verify that model is specified as well.
-            model = None
-            if "model" in llm_config["config_list"][0]:
-                model = llm_config["config_list"][0]["model"]
-            if model is None or len(model) == 0:
-                raise ValueError("Please specify a value for the 'model' in 'llm_config'.")
-
         if llm_config is False:
             self.llm_config = False
             self.client = None
         else:
             self.llm_config = self.DEFAULT_CONFIG.copy()
             if isinstance(llm_config, dict):
                 self.llm_config.update(llm_config)
+            # We still have a default `llm_config` because the user didn't
+            # specify anything. This won't work, so raise an error to avoid
+            # an obscure message from the OpenAI service.
+            if self.llm_config == self.DEFAULT_CONFIG:
+                raise ValueError("Please specify the value for 'llm_config'.")
             self.client = OpenAIWrapper(**self.llm_config)
 
         # Initialize standalone client cache object.

autogen/oai/client.py

@@ -345,15 +345,27 @@ def __init__(self, *, config_list: Optional[List[Dict[str, Any]]] = None, **base
                 and additional kwargs.
         """
         openai_config, extra_kwargs = self._separate_openai_config(base_config)
+        # This *may* work if the `llm_config` has specified the `model` attribute,
+        # so just warn here.
         if type(config_list) is list and len(config_list) == 0:
-            logger.warning("openai client was provided with an empty config_list, which may not be intended.")
+            logger.warning("OpenAI client was provided with an empty config_list, which may not be intended.")
+            # If the `llm_config` has no `model` then the call will fail. Abort now.
+            if "model" not in extra_kwargs:
+                raise ValueError("Please specify a value for the 'model' in 'llm_config'.")
 
         self._clients: List[ModelClient] = []
         self._config_list: List[Dict[str, Any]] = []
 
         if config_list:
             config_list = [config.copy() for config in config_list]  # make a copy before modifying
             for config in config_list:
+                # We require that each element of `config_list` has a non-empty value
+                # for `model` specified.
+                model = None
+                if "model" in config:
+                    model = config["model"]
+                if model is None or len(model) == 0:
+                    raise ValueError("Please specify a value for the 'model' in 'config_list'.")
                 self._register_default_client(config, openai_config)  # could modify the config
                 self._config_list.append(
                     {**extra_kwargs, **{k: v for k, v in config.items() if k not in self.openai_kwargs}}

test/agentchat/test_conversable_agent.py

@@ -781,20 +781,24 @@ def test_register_for_llm_without_LLM():
         assert e.args[0] == "Please specify the value for 'llm_config'."
 
 
+def test_register_for_llm_without_configuration_but_with_model_name():
+    ConversableAgent(name="agent", llm_config={"model": "gpt-4", "config_list": []})
+
+
 def test_register_for_llm_without_configuration():
     try:
         ConversableAgent(name="agent", llm_config={"config_list": []})
         assert False, "Expected ConversableAgent to throw ValueError."
     except ValueError as e:
-        assert e.args[0] == "Please specify at least one configuration in 'llm_config'."
+        assert e.args[0] == "Please specify a value for the 'model' in 'llm_config'."
 
 
 def test_register_for_llm_without_model_name():
     try:
         ConversableAgent(name="agent", llm_config={"config_list": [{"model": "", "api_key": ""}]})
         assert False, "Expected ConversableAgent to throw ValueError."
     except ValueError as e:
-        assert e.args[0] == "Please specify a value for the 'model' in 'llm_config'."
+        assert e.args[0] == "Please specify a value for the 'model' in 'config_list'."
 
 
 def test_register_for_execution():