fix: withdraw bep20 error

.github/workflows/build.yaml

@@ -24,7 +24,7 @@ jobs:
     - name: Make build-go
       run: make build-go
 
-  'build-solidity':
+  'build-test-solidity':
     name: make build-solidity
     runs-on: ubuntu-latest
     steps:
@@ -38,4 +38,4 @@ jobs:
       uses: foundry-rs/foundry-toolchain@v1
 
     - name: Make build-solidity
-      run: cd contracts && forge build
+      run: cd contracts && forge build && forge test

contracts/src/L2StandardBridgeBot.sol

@@ -1,6 +1,7 @@
 pragma solidity 0.8.20;
 
 import { Ownable } from "openzeppelin-contracts/contracts/access/Ownable.sol";
+import { IERC20 } from "openzeppelin-contracts/contracts/token/ERC20/IERC20.sol";
 
 interface IL2StandardBridge {
     function withdrawTo(
@@ -45,6 +46,11 @@ contract L2StandardBridgeBot is Ownable {
         } else {
             require(msg.value == delegationFee, "BEP20 withdrawal: msg.value does not equal to delegationFee");
 
+            IERC20 l2Token = IERC20(_l2Token);
+            bool approveSuccess = l2Token.approve(L2_STANDARD_BRIDGE_ADDRESS, _amount + l2Token.allowance(address(this), L2_STANDARD_BRIDGE_ADDRESS));
+            require(approveSuccess, "BEP20 withdrawal: approve failed");
+            bool transferSuccess = l2Token.transferFrom(msg.sender, address(this), _amount);
+            require(transferSuccess, "BEP20 withdrawal: transferFrom failed");
             L2_STANDARD_BRIDGE.withdrawTo{value: 0}(_l2Token, _to, _amount, _minGasLimit, _extraData);
         }
 

contracts/test/L2StandardBridgeBot.t.sol

@@ -0,0 +1,56 @@
+pragma solidity 0.8.20;
+
+import "forge-std/Test.sol";
+import { IERC20 } from "openzeppelin-contracts/contracts/token/ERC20/IERC20.sol";
+import { Ownable } from "openzeppelin-contracts/contracts/access/Ownable.sol";
+import "../src/L2StandardBridgeBot.sol";
+
+contract L2StandardBridgeBotTest is Test {
+    L2StandardBridgeBot bot;
+    uint256 opbnbMainnetFork;
+    address deployer = address(0x1234);
+    address usdt = 0xCF712f20c85421d00EAa1B6F6545AaEEb4492B75;
+    address user = 0x3977f9B1F4912a783B44aBa813dA388AC73a1428;
+    uint withdrawFee = 10000;
+    address constant LEGACY_ERC20_ETH = 0xDeadDeAddeAddEAddeadDEaDDEAdDeaDDeAD0000;
+
+    event WithdrawTo(address indexed from, address l2Token, address to, uint256 amount, uint32 minGasLimit, bytes extraData);
+
+    function setUp() public {
+        opbnbMainnetFork = vm.createFork("https://opbnb-testnet-rpc.bnbchain.org");
+        vm.selectFork(opbnbMainnetFork);
+        vm.rollFork(opbnbMainnetFork, 7125821);
+        bot = new L2StandardBridgeBot(payable(deployer), withdrawFee);
+    }
+
+    function test_RevertSetDelegationFeeNotOwner() public {
+        vm.expectRevert();
+        bot.setDelegationFee(100);
+    }
+
+    function test_setDelegationFee() public {
+        vm.prank(deployer);
+        bot.setDelegationFee(100);
+        assertEq(bot.delegationFee(), 100);
+    }
+
+    function test_withdrawBNB() public {
+        vm.prank(user);
+        uint amount = 100;
+        vm.expectEmit(true, false, false, true);
+        emit WithdrawTo(user, LEGACY_ERC20_ETH, user, amount, 200000, "");
+        bot.withdrawTo{value: withdrawFee + amount}(LEGACY_ERC20_ETH, user, amount, 200000, "");
+    }
+
+    function test_ERC20() public {
+        uint amount = 100;
+        uint balanceBefore = IERC20(usdt).balanceOf(user);
+        console2.log("balanceBefore", balanceBefore);
+        vm.prank(user);
+        IERC20(usdt).approve(address(bot), amount);
+        vm.prank(user);
+        vm.expectEmit(true, false, false, true);
+        emit WithdrawTo(user, usdt, user, amount, 200000, "");
+        bot.withdrawTo{value: withdrawFee}(usdt, user, amount, 200000, "");
+    }
+}