FakeListLLM Class — langchain Architecture

Source Code

libs/langchain/tests/unit_tests/agents/test_agent.py lines 46–80

class FakeListLLM(LLM):
    """Fake LLM for testing that outputs elements of a list."""

    responses: list[str]
    i: int = -1

    @override
    def _call(
        self,
        prompt: str,
        stop: list[str] | None = None,
        run_manager: CallbackManagerForLLMRun | None = None,
        **kwargs: Any,
    ) -> str:
        """Increment counter, and then return response in that index."""
        self.i += 1
        print(f"=== Mock Response #{self.i} ===")  # noqa: T201
        print(self.responses[self.i])  # noqa: T201
        return self.responses[self.i]

    def get_num_tokens(self, text: str) -> int:
        """Return number of tokens in text."""
        return len(text.split())

    async def _acall(self, *args: Any, **kwargs: Any) -> str:
        return self._call(*args, **kwargs)

    @property
    def _identifying_params(self) -> dict[str, Any]:
        return {}

    @property
    def _llm_type(self) -> str:
        """Return type of llm."""
        return "fake_list"