refactor: transfer to ICS20 first then burn (#296)

* feat: transfer to ICS20 first, then burn

* fix: approve ics20 to spend from user in relayer

* nit

cairo-contracts/packages/apps/src/tests/transfer.cairo

@@ -210,7 +210,13 @@ fn test_burn_ok() {
     call_contract(ics20.address, selector!("send_transfer_internal"), @msg_transfer);
 
     // Assert the `SendEvent` emitted.
-    spy.assert_send_event(ics20.address, SN_USER(), CS_USER(), prefixed_denom, cfg.amount);
+    spy
+        .assert_send_event(
+            ics20.address, SN_USER(), CS_USER(), prefixed_denom, cfg.amount,
+        ); // Assert if the transfer happens from the ICS20 address.
+
+    // Assert if the burn happens by the ICS20 contract.
+    spy.assert_transfer_event(erc20.address, SN_USER(), ics20.address, cfg.amount);
 
     // Check the balance of the sender.
     erc20.assert_balance(SN_USER(), 0);

cairo-contracts/packages/apps/src/transfer/components/transfer.cairo

@@ -694,7 +694,9 @@ pub mod TokenTransferComponent {
         ) {
             let token = self.get_token(denom.key());
 
-            token.burn(account, amount);
+            token.transfer_from(account, get_contract_address(), amount);
+
+            token.burn(get_contract_address(), amount);
         }
 
         fn refund_execute(

cairo-contracts/packages/contracts/src/tests/transfer.cairo

@@ -106,7 +106,7 @@ fn test_mint_burn_roundtrip() {
             ics20.address, CS_USER(), SN_USER(), prefixed_denom.clone(), transfer_cfg.amount, true,
         );
 
-    let erc20: ERC20Contract = token_address.into();
+    let mut erc20: ERC20Contract = token_address.into();
 
     // Assert if the transfer happens from the ICS20 address.
     spy.assert_transfer_event(erc20.address, ics20.address, SN_USER(), transfer_cfg.amount);
@@ -123,6 +123,9 @@ fn test_mint_burn_roundtrip() {
 
     start_cheat_caller_address(ics20.address, SN_USER());
 
+    // User approves the amount of burn allowance to the `TransferApp` contract.
+    erc20.approve(SN_USER(), ics20.address, transfer_cfg.amount);
+
     let msg_transfer = transfer_cfg.dummy_msg_transfer(prefixed_denom.clone(), CS_USER());
 
     // User approves the amount of allowance for the `TransferApp` contract.
@@ -131,6 +134,9 @@ fn test_mint_burn_roundtrip() {
     // Assert the `SendEvent` emitted.
     spy.assert_send_event(ics20.address, SN_USER(), CS_USER(), prefixed_denom, transfer_cfg.amount);
 
+    // Assert if the burn happens by the ICS20 contract.
+    spy.assert_transfer_event(erc20.address, SN_USER(), ics20.address, transfer_cfg.amount);
+
     // Check the balance of the sender.
     erc20.assert_balance(SN_USER(), 0);
 

relayer/crates/starknet-integration-tests/src/tests/clear_packets.rs

@@ -70,6 +70,7 @@ use ibc::core::host::types::identifiers::{PortId as IbcPortId, Sequence};
 use poseidon::Poseidon3Hasher;
 use sha2::{Digest, Sha256};
 use starknet::accounts::{Account, Call, ExecutionEncoding, SingleOwnerAccount};
+use starknet::core::types::U256;
 use starknet::macros::{selector, short_string};
 use starknet::providers::Provider;
 use starknet::signers::{LocalWallet, SigningKey};
@@ -542,6 +543,26 @@ fn test_query_unreceived_packets() -> Result<(), Error> {
 
         runtime.sleep(Duration::from_secs(2)).await;
 
+        // approve ics20 contract to spend the tokens for `address_starknet_b`
+        {
+            let call_data = cairo_encoding.encode(&product![
+                ics20_contract_address,
+                U256::from(transfer_quantity)
+            ])?;
+
+            let call = Call {
+                to: *ics20_token_address,
+                selector: selector!("approve"),
+                calldata: call_data,
+            };
+
+            let execution = starknet_account_b.execute_v3(vec![call]);
+
+            let tx_hash = execution.send().await?.transaction_hash;
+
+            starknet_chain.poll_tx_response(&tx_hash).await?;
+        }
+
         // Create Starknet to Cosmos transfer
         let starknet_ics20_send_message = {
             let current_starknet_time = starknet_chain.query_chain_status().await?.time;

relayer/crates/starknet-integration-tests/src/tests/ics20.rs

@@ -506,6 +506,26 @@ fn test_starknet_ics20_contract() -> Result<(), Error> {
 
         assert_eq!(balance_starknet_b_step_1.quantity, transfer_quantity.into());
 
+        // approve ics20 contract to spend the tokens for `address_starknet_b`
+        {
+            let call_data = cairo_encoding.encode(&product![
+                ics20_contract_address,
+                U256::from(transfer_quantity)
+            ])?;
+
+            let call = Call {
+                to: *ics20_token_address,
+                selector: selector!("approve"),
+                calldata: call_data,
+            };
+
+            let execution = starknet_account_b.execute_v3(vec![call]);
+
+            let tx_hash = execution.send().await?.transaction_hash;
+
+            starknet_chain.poll_tx_response(&tx_hash).await?;
+        }
+
         // create ibc transfer message
 
         let starknet_ics20_send_message = {