FakeChatModel Class — langchain Architecture

Architecture documentation for the FakeChatModel class in fake_chat_models.py from the langchain codebase.

Class python

Entity Profile

Dependency Diagram

graph TD
  71c97fb8_a1fa_dc3f_bbe9_eefe668fb2d7["FakeChatModel"]
  a3ea7a6e_c0f6_2e2b_7c6a_1f7b9fdaa248["SimpleChatModel"]
  71c97fb8_a1fa_dc3f_bbe9_eefe668fb2d7 -->|extends| a3ea7a6e_c0f6_2e2b_7c6a_1f7b9fdaa248
  625e90ff_0acf_2872_ee23_0e50b0ab92ed["fake_chat_models.py"]
  71c97fb8_a1fa_dc3f_bbe9_eefe668fb2d7 -->|defined in| 625e90ff_0acf_2872_ee23_0e50b0ab92ed
  989750ea_9a12_fcd7_8c9a_3fa986238821["_call()"]
  71c97fb8_a1fa_dc3f_bbe9_eefe668fb2d7 -->|method| 989750ea_9a12_fcd7_8c9a_3fa986238821
  5497658f_38e8_808c_7410_a4187e62abf2["_agenerate()"]
  71c97fb8_a1fa_dc3f_bbe9_eefe668fb2d7 -->|method| 5497658f_38e8_808c_7410_a4187e62abf2
  af4131e4_d267_bb89_bdfc_a0c5e3c7391b["_llm_type()"]
  71c97fb8_a1fa_dc3f_bbe9_eefe668fb2d7 -->|method| af4131e4_d267_bb89_bdfc_a0c5e3c7391b
  2480bcb7_5244_790b_1c91_ec1bafc16e70["_identifying_params()"]
  71c97fb8_a1fa_dc3f_bbe9_eefe668fb2d7 -->|method| 2480bcb7_5244_790b_1c91_ec1bafc16e70

Relationship Graph

Source Code

libs/core/langchain_core/language_models/fake_chat_models.py lines 192–224

class FakeChatModel(SimpleChatModel):
    """Fake Chat Model wrapper for testing purposes."""

    @override
    def _call(
        self,
        messages: list[BaseMessage],
        stop: list[str] | None = None,
        run_manager: CallbackManagerForLLMRun | None = None,
        **kwargs: Any,
    ) -> str:
        return "fake response"

    @override
    async def _agenerate(
        self,
        messages: list[BaseMessage],
        stop: list[str] | None = None,
        run_manager: AsyncCallbackManagerForLLMRun | None = None,
        **kwargs: Any,
    ) -> ChatResult:
        output_str = "fake response"
        message = AIMessage(content=output_str)
        generation = ChatGeneration(message=message)
        return ChatResult(generations=[generation])

    @property
    def _llm_type(self) -> str:
        return "fake-chat-model"

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