switchyard_libsy/algorithms/
noop.rs

1// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
2// SPDX-License-Identifier: Apache-2.0
3
4//! Test-only algorithm that returns a hard-coded response without calling a backend.
5
6use std::sync::Arc;
7
8use switchyard_protocol::{
9    AggLlmResponse, ContentBlock, LlmResponse, ModelId, Request, Response, ResponseOutput, Role,
10    StopReason,
11};
12
13use crate::core::algorithm::{Algorithm, Driver};
14use crate::{Result, RoutingOutcome};
15
16/// Test helper that returns a hard-coded response without routing or model I/O.
17pub struct Noop {}
18
19#[async_trait::async_trait]
20impl Algorithm for Noop {
21    fn name(&self) -> &str {
22        "noop"
23    }
24
25    async fn route(self: Arc<Self>, _driver: Driver, request: Request) -> Result<RoutingOutcome> {
26        let streaming = request.llm_request.stream;
27        let model_id = request
28            .model_id()
29            .unwrap_or_else(|| ModelId::from("switchyard/noop"));
30        tracing::info!(target = %model_id, "noop returned its synthetic response");
31        let aggregate = AggLlmResponse {
32            id: Some("switchyard-noop".to_string()),
33            model: Some(model_id.to_string()),
34            outputs: vec![ResponseOutput {
35                role: Role::Assistant,
36                content: vec![ContentBlock::Text {
37                    text: "OK".to_string(),
38                }],
39                stop_reason: Some(StopReason::EndTurn),
40            }],
41            ..Default::default()
42        };
43        let llm_response = if streaming {
44            LlmResponse::Stream(aggregate.into_stream())
45        } else {
46            LlmResponse::Agg(aggregate)
47        };
48        let response = Response {
49            llm_response,
50            metadata: request.metadata.clone(),
51        };
52        Ok(RoutingOutcome::answered(model_id, request, response))
53    }
54}
55
56#[cfg(test)]
57mod tests {
58    use switchyard_protocol::{LlmRequest, Message, Role};
59
60    use super::*;
61    use crate::core::testing::{echo, test_drive};
62
63    #[tokio::test]
64    async fn test_noop_algo() -> Result<()> {
65        const TEST_MODEL: &str = "test_noop_algo";
66        let request = Request {
67            llm_request: LlmRequest {
68                model: Some(TEST_MODEL.to_string()),
69                messages: vec![Message::text(Role::User, "hi")],
70                ..LlmRequest::default()
71            },
72            raw_request: None,
73            metadata: None,
74        };
75
76        // `Noop` synthesizes its own response and never offloads a call, so `echo` is
77        // never reached.
78        let a: Arc<dyn Algorithm> = Arc::new(Noop {});
79        let (selected_model, response) = test_drive(a, request, echo()).await?;
80        assert_eq!(selected_model, TEST_MODEL);
81        assert_eq!(response.selected_model(), Some(TEST_MODEL));
82        Ok(())
83    }
84
85    #[tokio::test]
86    async fn test_noop_algo_streams_when_requested() -> Result<()> {
87        let request = Request {
88            llm_request: LlmRequest {
89                model: Some("streaming-noop".to_string()),
90                messages: vec![Message::text(Role::User, "hi")],
91                stream: true,
92                ..LlmRequest::default()
93            },
94            raw_request: None,
95            metadata: None,
96        };
97
98        let algorithm: Arc<dyn Algorithm> = Arc::new(Noop {});
99        let (_, response) = test_drive(algorithm, request, echo()).await?;
100
101        assert!(matches!(response.llm_response, LlmResponse::Stream(_)));
102        Ok(())
103    }
104}
switchyard_libsy/algorithms/noop.rs

switchyard_libsy/algorithms/
noop.rs
