test: add unit tests of llms (#299)

src/llms/llm.py

@@ -70,9 +70,3 @@ def get_llm_by_type(
 # In the future, we will use reasoning_llm and vl_llm for different purposes
 # reasoning_llm = get_llm_by_type("reasoning")
 # vl_llm = get_llm_by_type("vision")
-
-
-if __name__ == "__main__":
-    # Initialize LLMs for different purposes - now these will be cached
-    basic_llm = get_llm_by_type("basic")
-    print(basic_llm.invoke("Hello"))

tests/unit/llms/test_llm.py

@@ -0,0 +1,70 @@
+# Copyright (c) 2025 Bytedance Ltd. and/or its affiliates
+# SPDX-License-Identifier: MIT
+
+import os
+import types
+import pytest
+from src.llms import llm
+
+
+class DummyChatOpenAI:
+    def __init__(self, **kwargs):
+        self.kwargs = kwargs
+
+    def invoke(self, msg):
+        return f"Echo: {msg}"
+
+
+@pytest.fixture(autouse=True)
+def patch_chat_openai(monkeypatch):
+    monkeypatch.setattr(llm, "ChatOpenAI", DummyChatOpenAI)
+
+
+@pytest.fixture
+def dummy_conf():
+    return {
+        "BASIC_MODEL": {"api_key": "test_key", "base_url": "http://test"},
+        "REASONING_MODEL": {"api_key": "reason_key"},
+        "VISION_MODEL": {"api_key": "vision_key"},
+    }
+
+
+def test_get_env_llm_conf(monkeypatch):
+    monkeypatch.setenv("BASIC_MODEL__API_KEY", "env_key")
+    monkeypatch.setenv("BASIC_MODEL__BASE_URL", "http://env")
+    conf = llm._get_env_llm_conf("basic")
+    assert conf["api_key"] == "env_key"
+    assert conf["base_url"] == "http://env"
+
+
+def test_create_llm_use_conf_merges_env(monkeypatch, dummy_conf):
+    monkeypatch.setenv("BASIC_MODEL__API_KEY", "env_key")
+    result = llm._create_llm_use_conf("basic", dummy_conf)
+    assert isinstance(result, DummyChatOpenAI)
+    assert result.kwargs["api_key"] == "env_key"
+    assert result.kwargs["base_url"] == "http://test"
+
+
+def test_create_llm_use_conf_invalid_type(dummy_conf):
+    with pytest.raises(ValueError):
+        llm._create_llm_use_conf("unknown", dummy_conf)
+
+
+def test_create_llm_use_conf_empty_conf(monkeypatch):
+    with pytest.raises(ValueError):
+        llm._create_llm_use_conf("basic", {})
+
+
+def test_get_llm_by_type_caches(monkeypatch, dummy_conf):
+    called = {}
+
+    def fake_load_yaml_config(path):
+        called["called"] = True
+        return dummy_conf
+
+    monkeypatch.setattr(llm, "load_yaml_config", fake_load_yaml_config)
+    llm._llm_cache.clear()
+    inst1 = llm.get_llm_by_type("basic")
+    inst2 = llm.get_llm_by_type("basic")
+    assert inst1 is inst2
+    assert called["called"]