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            upstream_headers: http::HeaderMap::new(),
52        };
53        Ok(RoutingOutcome::answered(model_id, request, response))
54    }
55}
56
57#[cfg(test)]
58mod tests {
59    use switchyard_protocol::{LlmRequest, Message, Role};
60
61    use super::*;
62    use crate::core::testing::{echo, test_drive};
63
64    #[tokio::test]
65    async fn test_noop_algo() -> Result<()> {
66        const TEST_MODEL: &str = "test_noop_algo";
67        let request = Request {
68            llm_request: LlmRequest {
69                model: Some(TEST_MODEL.to_string()),
70                messages: vec![Message::text(Role::User, "hi")],
71                ..LlmRequest::default()
72            },
73            raw_request: None,
74            metadata: None,
75        };
76
77        // `Noop` synthesizes its own response and never offloads a call, so `echo` is
78        // never reached.
79        let a: Arc<dyn Algorithm> = Arc::new(Noop {});
80        let (selected_model, response) = test_drive(a, request, echo()).await?;
81        assert_eq!(selected_model, TEST_MODEL);
82        assert_eq!(response.selected_model(), Some(TEST_MODEL));
83        Ok(())
84    }
85
86    #[tokio::test]
87    async fn test_noop_algo_streams_when_requested() -> Result<()> {
88        let request = Request {
89            llm_request: LlmRequest {
90                model: Some("streaming-noop".to_string()),
91                messages: vec![Message::text(Role::User, "hi")],
92                stream: true,
93                ..LlmRequest::default()
94            },
95            raw_request: None,
96            metadata: None,
97        };
98
99        let algorithm: Arc<dyn Algorithm> = Arc::new(Noop {});
100        let (_, response) = test_drive(algorithm, request, echo()).await?;
101
102        assert!(matches!(response.llm_response, LlmResponse::Stream(_)));
103        Ok(())
104    }
105}
switchyard_libsy/algorithms/noop.rs

switchyard_libsy/algorithms/
noop.rs
