test_no_retry_propagates_error() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_wrap_model_call.py lines 201–233

    def test_no_retry_propagates_error(self) -> None:
        """Test that error is propagated when middleware doesn't retry."""

        class FailingModel(BaseChatModel):
            """Model that always fails."""

            @override
            def _generate(
                self,
                messages: list[BaseMessage],
                stop: list[str] | None = None,
                run_manager: CallbackManagerForLLMRun | None = None,
                **kwargs: Any,
            ) -> ChatResult:
                msg = "Model error"
                raise ValueError(msg)

            @property
            def _llm_type(self) -> str:
                return "failing"

        class NoRetryMiddleware(AgentMiddleware):
            def wrap_model_call(
                self,
                request: ModelRequest,
                handler: Callable[[ModelRequest], ModelResponse],
            ) -> ModelCallResult:
                return handler(request)

        agent = create_agent(model=FailingModel(), middleware=[NoRetryMiddleware()])

        with pytest.raises(ValueError, match="Model error"):
            agent.invoke({"messages": [HumanMessage("Test")]})