test_async_dynamic_prompt_skipped_on_sync_invoke() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_decorators.py lines 774–797

def test_async_dynamic_prompt_skipped_on_sync_invoke() -> None:
    """Test async dynamic_prompt skipped on sync invoke.

    Test that async `dynamic_prompt` raises `NotImplementedError` when invoked via sync
    path (.invoke).

    When an async-only middleware is defined, it cannot be called from the sync path.
    The framework will raise NotImplementedError when trying to invoke the sync method.
    """
    calls = []

    @dynamic_prompt
    async def async_only_prompt(request: ModelRequest) -> str:
        calls.append("async_prompt")
        return "Async prompt"

    agent = create_agent(model=FakeToolCallingModel(), middleware=[async_only_prompt])

    # Async-only middleware raises NotImplementedError in sync path
    with pytest.raises(NotImplementedError):
        agent.invoke({"messages": [HumanMessage("Hello")]})

    # The async prompt was not called
    assert calls == []