test: add unit test

tests/litellm/litellm_core_utils/prompt_templates/test_litellm_core_utils_prompt_templates_common_utils.py

@@ -79,6 +79,19 @@ def test_handle_any_messages_to_chat_completion_str_messages_conversion_list():
     assert result[1]["input"] == json.dumps(messages[1])
 
 
+def test_handle_any_messages_to_chat_completion_str_messages_conversion_list_infinite_loop():
+    # Test that list handling doesn't cause infinite recursion
+    messages = [
+        {"role": "user", "content": "Hello"},
+        {"role": "assistant", "content": "Hi there"},
+    ]
+    # This should complete without stack overflow
+    result = handle_any_messages_to_chat_completion_str_messages_conversion(messages)
+    assert len(result) == 2
+    assert result[0]["input"] == json.dumps(messages[0])
+    assert result[1]["input"] == json.dumps(messages[1])
+
+
 def test_handle_any_messages_to_chat_completion_str_messages_conversion_dict():
     # Test with single dictionary message
     message = {"role": "user", "content": "Hello"}