test:unit tests for configuration (#291)

* test:unit tests for configuration

* test: update the test_configuration.py file

* test: reformate the test codes

tests/unit/config/test_configuration.py

@@ -0,0 +1,95 @@
+# Copyright (c) 2025 Bytedance Ltd. and/or its affiliates
+# SPDX-License-Identifier: MIT
+
+import os
+import pytest
+import sys
+import types
+from pathlib import Path
+import builtins
+import importlib
+from src.config.configuration import Configuration
+
+# Patch sys.path so relative import works
+
+# Patch Resource for import
+mock_resource = type("Resource", (), {})
+
+# Patch src.rag.retriever.Resource for import
+
+module_name = "src.rag.retriever"
+if module_name not in sys.modules:
+    retriever_mod = types.ModuleType(module_name)
+    retriever_mod.Resource = mock_resource
+    sys.modules[module_name] = retriever_mod
+
+# Relative import of Configuration
+
+
+def test_default_configuration():
+    config = Configuration()
+    assert config.resources == []
+    assert config.max_plan_iterations == 1
+    assert config.max_step_num == 3
+    assert config.max_search_results == 3
+    assert config.mcp_settings is None
+
+
+def test_from_runnable_config_with_config_dict(monkeypatch):
+    config_dict = {
+        "configurable": {
+            "max_plan_iterations": 5,
+            "max_step_num": 7,
+            "max_search_results": 10,
+            "mcp_settings": {"foo": "bar"},
+        }
+    }
+    config = Configuration.from_runnable_config(config_dict)
+    assert config.max_plan_iterations == 5
+    assert config.max_step_num == 7
+    assert config.max_search_results == 10
+    assert config.mcp_settings == {"foo": "bar"}
+
+
+def test_from_runnable_config_with_env_override(monkeypatch):
+    monkeypatch.setenv("MAX_PLAN_ITERATIONS", "9")
+    monkeypatch.setenv("MAX_STEP_NUM", "11")
+    config_dict = {
+        "configurable": {
+            "max_plan_iterations": 2,
+            "max_step_num": 3,
+            "max_search_results": 4,
+        }
+    }
+    config = Configuration.from_runnable_config(config_dict)
+    # Environment variables take precedence and are strings
+    assert config.max_plan_iterations == "9"
+    assert config.max_step_num == "11"
+    assert config.max_search_results == 4  # not overridden
+    # Clean up
+    monkeypatch.delenv("MAX_PLAN_ITERATIONS")
+    monkeypatch.delenv("MAX_STEP_NUM")
+
+
+def test_from_runnable_config_with_none_and_falsy(monkeypatch):
+    config_dict = {
+        "configurable": {
+            "max_plan_iterations": None,
+            "max_step_num": 0,  # falsy, should be skipped
+            "max_search_results": "",
+        }
+    }
+    config = Configuration.from_runnable_config(config_dict)
+    # Should fall back to defaults for skipped/falsy values
+    assert config.max_plan_iterations == 1
+    assert config.max_step_num == 3
+    assert config.max_search_results == 3
+
+
+def test_from_runnable_config_with_no_config():
+    config = Configuration.from_runnable_config()
+    assert config.max_plan_iterations == 1
+    assert config.max_step_num == 3
+    assert config.max_search_results == 3
+    assert config.resources == []
+    assert config.mcp_settings is None