feat: Tycho encoder validation

Validates:
- Proper sequence of input, output, and first/last swap tokens for wrap/unwrap cases
- All solutions contain at least one swap
- Only exact in solutions are inputted (since we don't yet support exact out)

src/encoding/evm/constants.rs

@@ -0,0 +1,10 @@
+use alloy_primitives::hex;
+use lazy_static::lazy_static;
+use tycho_core::Bytes;
+
+lazy_static! {
+    pub static ref NATIVE_ADDRESS: Bytes =
+        Bytes::from(hex!("0000000000000000000000000000000000000000").to_vec());
+    pub static ref WETH_ADDRESS: Bytes =
+        Bytes::from(hex!("c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2").to_vec());
+}

src/encoding/evm/mod.rs

@@ -1,4 +1,5 @@
 pub mod approvals;
+mod constants;
 mod models;
 mod strategy_encoder;
 mod swap_encoder;

src/encoding/evm/tycho_encoder.rs

@@ -5,6 +5,7 @@ use tycho_core::{models::Chain, Bytes};
 
 use crate::encoding::{
     errors::EncodingError,
+    evm::constants::{NATIVE_ADDRESS, WETH_ADDRESS},
     models::{NativeAction, Solution, Transaction},
     strategy_encoder::StrategySelector,
     tycho_encoder::TychoEncoder,
@@ -38,11 +39,7 @@ impl<S: StrategySelector> TychoEncoder<S> for EVMTychoEncoder<S> {
     ) -> Result<Vec<Transaction>, EncodingError> {
         let mut transactions: Vec<Transaction> = Vec::new();
         for solution in solutions.iter() {
-            if solution.exact_out {
+            self.validate_solution(solution)?;
-                return Err(EncodingError::FatalError(
-                    "Currently only exact input solutions are supported".to_string(),
-                ));
-            }
 
             let router_address = solution
                 .router_address
@@ -70,15 +67,62 @@ impl<S: StrategySelector> TychoEncoder<S> for EVMTychoEncoder<S> {
         }
         Ok(transactions)
     }
+
+    fn validate_solution(&self, solution: &Solution) -> Result<(), EncodingError> {
+        if solution.exact_out {
+            return Err(EncodingError::FatalError(
+                "Currently only exact input solutions are supported".to_string(),
+            ));
+        }
+        if solution.swaps.is_empty() {
+            return Err(EncodingError::FatalError("No swaps found in solution".to_string()));
+        }
+        if let Some(native_action) = solution.clone().native_action {
+            if native_action == NativeAction::Wrap {
+                if let Some(first_swap) = solution.swaps.first() {
+                    if first_swap.token_in != *WETH_ADDRESS {
+                        return Err(EncodingError::FatalError(
+                            "WETH must be the first swap's input in order to wrap".to_string(),
+                        ));
+                    }
+                }
+                if solution.given_token != *NATIVE_ADDRESS {
+                    return Err(EncodingError::FatalError(
+                        "ETH must be the input token in order to wrap".to_string(),
+                    ));
+                }
+            } else if native_action == NativeAction::Unwrap {
+                if let Some(last_swap) = solution.swaps.last() {
+                    if last_swap.token_out != *WETH_ADDRESS {
+                        return Err(EncodingError::FatalError(
+                            "WETH must be the last swap's output in order to unwrap".to_string(),
+                        ));
+                    }
+                }
+                if solution.checked_token != *NATIVE_ADDRESS {
+                    return Err(EncodingError::FatalError(
+                        "ETH must be the output token in order to unwrap".to_string(),
+                    ));
+                }
+            }
+        }
+        Ok(())
+    }
 }
 
 #[cfg(test)]
 mod tests {
+    use tycho_core::dto::ProtocolComponent;
+
     use super::*;
-    use crate::encoding::strategy_encoder::StrategyEncoder;
+    use crate::encoding::{models::Swap, strategy_encoder::StrategyEncoder};
 
     struct MockStrategySelector;
 
+    fn dai() -> Bytes {
+        Bytes::from_str("0x6b175474e89094c44da98b954eedeac495271d0f").unwrap()
+    }
+
     impl StrategySelector for MockStrategySelector {
         fn select_strategy(
             &self,
@@ -107,7 +151,7 @@ mod tests {
         }
     }
 
-    fn get_mocker_tycho_encoder() -> EVMTychoEncoder<MockStrategySelector> {
+    fn get_mocked_tycho_encoder() -> EVMTychoEncoder<MockStrategySelector> {
         let strategy_selector = MockStrategySelector;
         EVMTychoEncoder::new(
             strategy_selector,
@@ -120,13 +164,25 @@ mod tests {
 
     #[test]
     fn test_encode_router_calldata() {
-        let encoder = get_mocker_tycho_encoder();
+        let encoder = get_mocked_tycho_encoder();
-
         let eth_amount_in = BigUint::from(1000u32);
+        let swap = Swap {
+            component: ProtocolComponent {
+                id: "0xA478c2975Ab1Ea89e8196811F51A7B7Ade33eB11".to_string(),
+                protocol_system: "uniswap_v2".to_string(),
+                ..Default::default()
+            },
+            token_in: WETH_ADDRESS.clone(),
+            token_out: dai(),
+            split: 0f64,
+        };
+
         let solution = Solution {
             exact_out: false,
             given_amount: eth_amount_in.clone(),
+            given_token: NATIVE_ADDRESS.clone(),
             router_address: None,
+            swaps: vec![swap],
             native_action: Some(NativeAction::Wrap),
             ..Default::default()
         };
@@ -142,15 +198,13 @@ mod tests {
     }
 
     #[test]
-    fn test_encode_router_calldata_fails_for_exact_out() {
+    fn test_validate_fails_for_exact_out() {
-        let encoder = get_mocker_tycho_encoder();
+        let encoder = get_mocked_tycho_encoder();
-
         let solution = Solution {
             exact_out: true, // This should cause an error
             ..Default::default()
         };
-
+        let result = encoder.validate_solution(&solution);
-        let result = encoder.encode_router_calldata(vec![solution]);
 
         assert!(result.is_err());
         assert_eq!(
@@ -160,4 +214,212 @@ mod tests {
             )
         );
     }
+
+    #[test]
+    fn test_validate_passes_for_wrap() {
+        let encoder = get_mocked_tycho_encoder();
+        let swap = Swap {
+            component: ProtocolComponent {
+                id: "0xA478c2975Ab1Ea89e8196811F51A7B7Ade33eB11".to_string(),
+                protocol_system: "uniswap_v2".to_string(),
+                ..Default::default()
+            },
+            token_in: WETH_ADDRESS.clone(),
+            token_out: dai(),
+            split: 0f64,
+        };
+
+        let solution = Solution {
+            exact_out: false,
+            given_token: NATIVE_ADDRESS.clone(),
+            checked_token: dai(),
+            check_amount: None,
+            swaps: vec![swap],
+            native_action: Some(NativeAction::Wrap),
+            ..Default::default()
+        };
+
+        let result = encoder.validate_solution(&solution);
+
+        assert!(result.is_ok());
+    }
+
+    #[test]
+    fn test_validate_fails_for_wrap_wrong_input() {
+        let encoder = get_mocked_tycho_encoder();
+        let swap = Swap {
+            component: ProtocolComponent {
+                id: "0xA478c2975Ab1Ea89e8196811F51A7B7Ade33eB11".to_string(),
+                protocol_system: "uniswap_v2".to_string(),
+                ..Default::default()
+            },
+            token_in: WETH_ADDRESS.clone(),
+            token_out: dai(),
+            split: 0f64,
+        };
+
+        let solution = Solution {
+            exact_out: false,
+            given_token: WETH_ADDRESS.clone(),
+            swaps: vec![swap],
+            native_action: Some(NativeAction::Wrap),
+            ..Default::default()
+        };
+
+        let result = encoder.validate_solution(&solution);
+
+        assert!(result.is_err());
+        assert_eq!(
+            result.err().unwrap(),
+            EncodingError::FatalError("ETH must be the input token in order to wrap".to_string())
+        );
+    }
+
+    #[test]
+    fn test_validate_fails_for_wrap_wrong_first_swap() {
+        let encoder = get_mocked_tycho_encoder();
+        let swap = Swap {
+            component: ProtocolComponent {
+                id: "0xA478c2975Ab1Ea89e8196811F51A7B7Ade33eB11".to_string(),
+                protocol_system: "uniswap_v2".to_string(),
+                ..Default::default()
+            },
+            token_in: NATIVE_ADDRESS.clone(),
+            token_out: dai(),
+            split: 0f64,
+        };
+
+        let solution = Solution {
+            exact_out: false,
+            given_token: NATIVE_ADDRESS.clone(),
+            swaps: vec![swap],
+            native_action: Some(NativeAction::Wrap),
+            ..Default::default()
+        };
+
+        let result = encoder.validate_solution(&solution);
+
+        assert!(result.is_err());
+        assert_eq!(
+            result.err().unwrap(),
+            EncodingError::FatalError(
+                "WETH must be the first swap's input in order to wrap".to_string()
+            )
+        );
+    }
+
+    #[test]
+    fn test_validate_fails_no_swaps() {
+        let encoder = get_mocked_tycho_encoder();
+        let solution = Solution {
+            exact_out: false,
+            given_token: NATIVE_ADDRESS.clone(),
+            swaps: vec![],
+            native_action: Some(NativeAction::Wrap),
+            ..Default::default()
+        };
+
+        let result = encoder.validate_solution(&solution);
+
+        assert!(result.is_err());
+        assert_eq!(
+            result.err().unwrap(),
+            EncodingError::FatalError("No swaps found in solution".to_string())
+        );
+    }
+
+    #[test]
+    fn test_validate_passes_for_unwrap() {
+        let encoder = get_mocked_tycho_encoder();
+        let swap = Swap {
+            component: ProtocolComponent {
+                id: "0xA478c2975Ab1Ea89e8196811F51A7B7Ade33eB11".to_string(),
+                protocol_system: "uniswap_v2".to_string(),
+                ..Default::default()
+            },
+            token_in: dai(),
+            token_out: WETH_ADDRESS.clone(),
+            split: 0f64,
+        };
+
+        let solution = Solution {
+            exact_out: false,
+            checked_token: NATIVE_ADDRESS.clone(),
+            check_amount: None,
+            swaps: vec![swap],
+            native_action: Some(NativeAction::Unwrap),
+            ..Default::default()
+        };
+
+        let result = encoder.validate_solution(&solution);
+
+        assert!(result.is_ok());
+    }
+
+    #[test]
+    fn test_validate_fails_for_unwrap_wrong_output() {
+        let encoder = get_mocked_tycho_encoder();
+        let swap = Swap {
+            component: ProtocolComponent {
+                id: "0xA478c2975Ab1Ea89e8196811F51A7B7Ade33eB11".to_string(),
+                protocol_system: "uniswap_v2".to_string(),
+                ..Default::default()
+            },
+            token_in: dai(),
+            token_out: WETH_ADDRESS.clone(),
+            split: 0f64,
+        };
+
+        let solution = Solution {
+            exact_out: false,
+            given_token: dai(),
+            checked_token: WETH_ADDRESS.clone(),
+            swaps: vec![swap],
+            native_action: Some(NativeAction::Unwrap),
+            ..Default::default()
+        };
+
+        let result = encoder.validate_solution(&solution);
+
+        assert!(result.is_err());
+        assert_eq!(
+            result.err().unwrap(),
+            EncodingError::FatalError(
+                "ETH must be the output token in order to unwrap".to_string()
+            )
+        );
+    }
+
+    #[test]
+    fn test_validate_fails_for_unwrap_wrong_last_swap() {
+        let encoder = get_mocked_tycho_encoder();
+        let swap = Swap {
+            component: ProtocolComponent {
+                id: "0xA478c2975Ab1Ea89e8196811F51A7B7Ade33eB11".to_string(),
+                protocol_system: "uniswap_v2".to_string(),
+                ..Default::default()
+            },
+            token_in: dai(),
+            token_out: NATIVE_ADDRESS.clone(),
+            split: 0f64,
+        };
+
+        let solution = Solution {
+            exact_out: false,
+            given_token: NATIVE_ADDRESS.clone(),
+            swaps: vec![swap],
+            native_action: Some(NativeAction::Unwrap),
+            ..Default::default()
+        };
+
+        let result = encoder.validate_solution(&solution);
+
+        assert!(result.is_err());
+        assert_eq!(
+            result.err().unwrap(),
+            EncodingError::FatalError(
+                "WETH must be the last swap's output in order to unwrap".to_string()
+            )
+        );
+    }
 }

src/encoding/tycho_encoder.rs

@@ -10,4 +10,6 @@ pub trait TychoEncoder<S: StrategySelector> {
         &self,
         solutions: Vec<Solution>,
     ) -> Result<Vec<Transaction>, EncodingError>;
+
+    fn validate_solution(&self, solution: &Solution) -> Result<(), EncodingError>;
 }