[Core] Improve config_list_from_json (microsoft#1026)

* Improve config_list_from_json
The `env_or_file` variabe can point to an
environment variable of file path.

* Update autogen/oai/openai_utils.py

Co-authored-by: Chi Wang <wang.chi@microsoft.com>

* Use "with" to open config file

* Remove unused.

* Remove accidental added file

---------

Co-authored-by: Eric Zhu <ekzhu@users.noreply.github.com>
Co-authored-by: Chi Wang <wang.chi@microsoft.com>

autogen/oai/openai_utils.py

@@ -1,9 +1,10 @@
-import os
 import json
+import logging
+import os
 import tempfile
 from pathlib import Path
-from typing import List, Optional, Dict, Set, Union
-import logging
+from typing import Dict, List, Optional, Set, Union
+
 from dotenv import find_dotenv, load_dotenv
 
 try:
@@ -416,7 +417,8 @@ def config_list_from_json(
     of acceptable values for that field, the configuration will still be considered a match.
 
     Args:
-        env_or_file (str): The name of the environment variable or the filename containing the JSON data.
+        env_or_file (str): The name of the environment variable, the filename, or the environment variable of the filename
+            that containing the JSON data.
         file_location (str, optional): The directory path where the file is located, if `env_or_file` is a filename.
         filter_dict (dict, optional): A dictionary specifying the filtering criteria for the configurations, with
             keys representing field names and values being lists or sets of acceptable values for those fields.
@@ -435,10 +437,21 @@ def config_list_from_json(
     Returns:
         List[Dict]: A list of configuration dictionaries that match the filtering criteria specified in `filter_dict`.
     """
-    json_str = os.environ.get(env_or_file)
-    if json_str:
+    env_str = os.environ.get(env_or_file)
+
+    if env_str:
+        # The environment variable exists. We should use information from it.
+        if os.path.exists(env_str):
+            # It is a file location, and we need to load the json from the file.
+            with open(env_str, "r") as file:
+                json_str = file.read()
+        else:
+            # Else, it should be a JSON string by itself.
+            json_str = env_str
         config_list = json.loads(json_str)
     else:
+        # The environment variable does not exist.
+        # So, `env_or_file` is a filename. We should use the file location.
         config_list_path = os.path.join(file_location, env_or_file)
         try:
             with open(config_list_path) as json_file:

test/oai/test_utils.py

@@ -1,10 +1,12 @@
-import os
 import json
-import pytest
 import logging
+import os
 import tempfile
 from unittest import mock
 from unittest.mock import patch
+
+import pytest
+
 import autogen  # noqa: E402
 from autogen.oai.openai_utils import DEFAULT_AZURE_API_VERSION
 
@@ -87,13 +89,32 @@ def test_config_list_from_json():
         config_list_2 = autogen.config_list_from_json("config_list_test")
         assert config_list == config_list_2
 
+        # Test: the env variable is set to a file path with folder name inside.
         config_list_3 = autogen.config_list_from_json(
             tmp_file.name, filter_dict={"model": ["gpt", "gpt-4", "gpt-4-32k"]}
         )
         assert all(config.get("model") in ["gpt-4", "gpt"] for config in config_list_3)
 
         del os.environ["config_list_test"]
 
+        # Test: using the `file_location` parameter.
+        config_list_4 = autogen.config_list_from_json(
+            os.path.basename(tmp_file.name),
+            file_location=os.path.dirname(tmp_file.name),
+            filter_dict={"model": ["gpt4", "gpt-4-32k"]},
+        )
+
+        assert all(config.get("model") in ["gpt4", "gpt-4-32k"] for config in config_list_4)
+
+        # Test: the env variable is set to a file path.
+        fd, temp_name = tempfile.mkstemp()
+        json.dump(config_list, os.fdopen(fd, "w+"), indent=4)
+        os.environ["config_list_test"] = temp_name
+        config_list_5 = autogen.config_list_from_json("config_list_test")
+        assert config_list_5 == config_list_2
+
+        del os.environ["config_list_test"]
+
 
 def test_config_list_openai_aoai():
     # Testing the functionality for loading configurations for different API types