test_custom_model_instance() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_tool_emulator.py lines 379–406

    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)