From f5bcd31d66d20f62ba547334f4ce807248f406c6 Mon Sep 17 00:00:00 2001
From: TAMARA LIPOWSKI <data.lipowski@extaccount.com>
Date: Thu, 4 Sep 2025 00:39:40 -0400
Subject: [PATCH] feat: Rust testing SDK - implement get_amount_out simulation

---
 protocol-testing/Cargo.lock         |  2 +
 protocol-testing/Cargo.toml         |  2 +
 protocol-testing/src/test_runner.rs | 62 +++++++++++++++++++++++------
 3 files changed, 54 insertions(+), 12 deletions(-)

diff --git a/protocol-testing/Cargo.lock b/protocol-testing/Cargo.lock
index b2a8f31..a6cb008 100644
--- a/protocol-testing/Cargo.lock
+++ b/protocol-testing/Cargo.lock
@@ -5429,6 +5429,8 @@ dependencies = [
  "glob",
  "hex",
  "miette",
+ "num-bigint",
+ "num-traits",
  "postgres",
  "serde",
  "serde_json",
diff --git a/protocol-testing/Cargo.toml b/protocol-testing/Cargo.toml
index c38f8f8..aa0462c 100644
--- a/protocol-testing/Cargo.toml
+++ b/protocol-testing/Cargo.toml
@@ -14,6 +14,8 @@ tycho-client = "0.82.0"
 tycho-simulation = { git = "https://github.com/propeller-heads/tycho-simulation.git", tag = "0.156.0", features = ["evm"] }
 ## TODO: for local development
 #tycho-simulation = { path = "../../tycho-simulation" }
+num-bigint = "0.4"
+num-traits = "0.2"
 # EVM dependencies
 alloy = { version = "1.0.27", features = ["arbitrary", "json", "dyn-abi", "sol-types", "contract", "provider-http"] }
 tokio = { version = "1", features = ["full"] }
diff --git a/protocol-testing/src/test_runner.rs b/protocol-testing/src/test_runner.rs
index 75bb944..b9fe8a4 100644
--- a/protocol-testing/src/test_runner.rs
+++ b/protocol-testing/src/test_runner.rs
@@ -6,6 +6,8 @@ use figment::{
     Figment,
 };
 use miette::{miette, IntoDiagnostic, WrapErr};
+use num_bigint::BigUint;
+use num_traits::Zero;
 use postgres::{Client, Error, NoTls};
 use tokio::runtime::Runtime;
 use tracing::{debug, error, info};
@@ -406,18 +408,54 @@ fn validate_state(
                 .map(|price| info!("Spot price {:?}: {:?}", formatted_token_str, price))
                 .map_err(|e| info!("Error calculating spot price for Pool {:?}: {:?}", id, e))
                 .ok();
-            // let amount_in =
-            //     BigUint::from(1u32) * BigUint::from(10u32).pow(tokens[0].decimals as u32);
-            // state
-            //     .get_amount_out(amount_in, &tokens[0], &tokens[1])
-            //     .map(|result| {
-            //         println!(
-            //             "Amount out for trading 1 {:?} -> {:?}: {:?} (takes {:?} gas)",
-            //             &tokens[0].symbol, &tokens[1].symbol, result.amount, result.gas
-            //         )
-            //     })
-            //     .map_err(|e| eprintln!("Error calculating amount out for Pool {:?}: {:?}", id,
-            // e))     .ok();
+
+            // Test get_amount_out with different percentages of limits. The reserves or limits are
+            // relevant because we need to know how much to test with. We don’t know if a pool is
+            // going to revert with 10 or 10 million USDC, for example, so by using the limits we
+            // can use “safe values” where the sim shouldn’t break.
+            let percentages = [0.001, 0.01, 0.1];
+            for percentage in &percentages {
+                // Get limits for this token pair
+                let limits = state
+                    .get_limits(tokens[0].address.clone(), tokens[1].address.clone())
+                    .map_err(|e| info!("Error getting limits for Pool {:?}: {:?}", id, e))
+                    .ok();
+
+                if let Some((max_input, _max_output)) = limits {
+                    // Calculate test amount as percentage of max input
+                    let percentage_biguint = BigUint::from((percentage * 1000.0) as u32);
+                    let thousand = BigUint::from(1000u32);
+                    let amount_in = (&max_input * &percentage_biguint) / &thousand;
+
+                    // Skip if amount is zero
+                    if amount_in.is_zero() {
+                        continue;
+                    }
+
+                    state
+                        .get_amount_out(amount_in.clone(), &tokens[0], &tokens[1])
+                        .map(|result| {
+                            info!(
+                                "Amount out for trading {:.1}% of max ({} -> {}): {} {} (gas: {})",
+                                percentage * 100.0,
+                                &tokens[0].symbol,
+                                &tokens[1].symbol,
+                                result.amount,
+                                &tokens[1].symbol,
+                                result.gas
+                            )
+                        })
+                        .map_err(|e| {
+                            info!(
+                                "Error calculating amount out for Pool {:?} at {:.1}%: {:?}",
+                                id,
+                                percentage * 100.0,
+                                e
+                            )
+                        })
+                        .ok();
+                }
+            }
         }
     }