TestLLMToolEmulatorModelConfiguration Class — langchain Architecture

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_tool_emulator.py lines 363–418

class TestLLMToolEmulatorModelConfiguration:
    """Test custom model configuration for emulation."""

    def test_custom_model_string(self) -> None:
        """Test passing a model string for emulation."""
        # Just test that initialization works - don't require anthropic package
        try:
            emulator = LLMToolEmulator(
                tools=["get_weather"], model="anthropic:claude-sonnet-4-5-20250929"
            )
            assert emulator.model is not None
            assert "get_weather" in emulator.tools_to_emulate
        except ImportError:
            # If anthropic isn't installed, that's fine for this unit test
            pass

    def test_custom_model_instance(self) -> None:
        """Test passing a BaseChatModel instance for emulation."""
        agent_model = FakeModel(
            messages=cycle(
                [
                    AIMessage(
                        content="",
                        tool_calls=[{"name": "search_web", "id": "1", "args": {"query": "test"}}],
                    ),
                    AIMessage(content="Done."),
                ]
            )
        )

        custom_emulator_model = FakeEmulatorModel(responses=["Custom emulated response"])

        emulator = LLMToolEmulator(tools=["search_web"], model=custom_emulator_model)

        agent = create_agent(
            model=agent_model,
            tools=[search_web],
            middleware=[emulator],
        )

        result = agent.invoke({"messages": [HumanMessage("Search for test")]})

        # Should use the custom model for emulation
        assert isinstance(result["messages"][-1], AIMessage)

    def test_default_model_used_when_none(self) -> None:
        """Test that default model is used when model=None."""
        # Just test that initialization doesn't fail - don't require anthropic package
        # The actual default model requires langchain_anthropic which may not be installed
        try:
            emulator = LLMToolEmulator(tools=["get_weather"], model=None)
            assert emulator.model is not None
        except ImportError:
            # If anthropic isn't installed, that's fine for this unit test
            # The integration tests will verify the full functionality
            pass