update lending contract and lending test case

contracts/ytLending/Lending.sol

@@ -182,6 +182,7 @@ contract Lending is
 
     /**
      * @notice 取出基础资产（如果余额不足会自动借款）
+     * @dev 如果用户余额不足，会自动借款，借款金额为 amount，借款利率为 borrowRate，借款期限为 borrowPeriod
      */
     function withdraw(uint256 amount) external override nonReentrant whenNotPaused {
         accrueInterest();
@@ -224,6 +225,7 @@ contract Lending is
 
     /**
      * @notice 存入抵押品
+     * @dev 由于不涉及债务计算，存入抵押品反而会让账户更安全，所以不用更新利息因子
      */
     function supplyCollateral(address asset, uint256 amount) external override nonReentrant whenNotPaused {
         AssetConfig memory config = assetConfigs[asset];
@@ -272,8 +274,6 @@ contract Lending is
         int104 oldPrincipal = user.principal;
         
         // 计算当前实际余额（含利息）
-        // 如果 principal >= 0（存款），使用 supplyIndex
-        // 如果 principal < 0（借款），使用 borrowIndex
         uint256 index = oldPrincipal >= 0 ? supplyIndex : borrowIndex;
         int256 oldBalance = LendingMath.principalToBalance(oldPrincipal, index);
         
@@ -370,13 +370,19 @@ contract Lending is
         // 计算偿还和供应金额
         (uint104 repayAmount, uint104 supplyAmount) = LendingMath.repayAndSupplyAmount(oldPrincipal, newPrincipal);
         
-        // 更新全局状态
+        // 更新全局状态（储备金通过减少 totalBorrowBase 和增加 totalSupplyBase 来承担坏账）
-        // 储备金通过减少 totalBorrowBase 和增加 totalSupplyBase 来承担坏账
         totalSupplyBase += supplyAmount;
         totalBorrowBase -= repayAmount;
         
-        // 计算协议支付的债务（坏账部分）
+        // 计算协议承担的坏账部分
-        uint256 basePaidOut = uint256(newBalance - oldBalance);
+        // 坏账 = 用户债务 - 抵押品价值（当抵押品不足时）
+        uint256 basePaidOut = 0;
+        if (int256(collateralInBase) < -oldBalance) {
+            // 抵押品不足以覆盖债务，差额由协议储备金承担
+            basePaidOut = uint256(-oldBalance) - collateralInBase;
+        }
+        // 如果 collateralInBase >= -oldBalance，说明抵押品足够，无坏账
+        
         uint256 valueOfBasePaidOut = (basePaidOut * basePrice) / baseScale;
         
         // 发射债务吸收事件
@@ -513,18 +519,6 @@ contract Lending is
         return totalValue;
     }
 
-    /**
-     * @notice 获取最小借款抵押率
-     */
-    function _getMinBorrowCollateralFactor() internal view returns (uint64) {
-        uint64 minFactor = type(uint64).max;
-        for (uint i = 0; i < assetList.length; i++) {
-            uint64 factor = assetConfigs[assetList[i]].borrowCollateralFactor;
-            if (factor < minFactor) minFactor = factor;
-        }
-        return minFactor;
-    }
-
     // ========== View Functions ==========
 
     function getBalance(address account) external view override returns (int256) {

out/build-info/4d57c48057fc3574.json

@@ -0,0 +1 @@
+{"id":"4d57c48057fc3574","source_id_to_path":{"0":"contracts/ytLending/Configurator.sol","1":"contracts/ytLending/ConfiguratorStorage.sol","2":"contracts/ytLending/Lending.sol","3":"contracts/ytLending/LendingConfiguration.sol","4":"contracts/ytLending/LendingFactory.sol","5":"contracts/ytLending/LendingMath.sol","6":"contracts/ytLending/LendingStorage.sol","7":"contracts/ytLending/interfaces/ILending.sol","8":"contracts/ytLending/interfaces/IPriceFeed.sol","9":"lib/forge-std/src/Base.sol","10":"lib/forge-std/src/StdAssertions.sol","11":"lib/forge-std/src/StdChains.sol","12":"lib/forge-std/src/StdCheats.sol","13":"lib/forge-std/src/StdConstants.sol","14":"lib/forge-std/src/StdError.sol","15":"lib/forge-std/src/StdInvariant.sol","16":"lib/forge-std/src/StdJson.sol","17":"lib/forge-std/src/StdMath.sol","18":"lib/forge-std/src/StdStorage.sol","19":"lib/forge-std/src/StdStyle.sol","20":"lib/forge-std/src/StdToml.sol","21":"lib/forge-std/src/StdUtils.sol","22":"lib/forge-std/src/Test.sol","23":"lib/forge-std/src/Vm.sol","24":"lib/forge-std/src/console.sol","25":"lib/forge-std/src/console2.sol","26":"lib/forge-std/src/interfaces/IMulticall3.sol","27":"lib/forge-std/src/safeconsole.sol","28":"node_modules/@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol","29":"node_modules/@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol","30":"node_modules/@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol","31":"node_modules/@openzeppelin/contracts-upgradeable/utils/ContextUpgradeable.sol","32":"node_modules/@openzeppelin/contracts-upgradeable/utils/PausableUpgradeable.sol","33":"node_modules/@openzeppelin/contracts-upgradeable/utils/ReentrancyGuardUpgradeable.sol","34":"node_modules/@openzeppelin/contracts/access/Ownable.sol","35":"node_modules/@openzeppelin/contracts/interfaces/IERC1363.sol","36":"node_modules/@openzeppelin/contracts/interfaces/IERC165.sol","37":"node_modules/@openzeppelin/contracts/interfaces/IERC1967.sol","38":"node_modules/@openzeppelin/contracts/interfaces/IERC20.sol","39":"node_modules/@openzeppelin/contracts/interfaces/draft-IERC1822.sol","40":"node_modules/@openzeppelin/contracts/interfaces/draft-IERC6093.sol","41":"node_modules/@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol","42":"node_modules/@openzeppelin/contracts/proxy/ERC1967/ERC1967Utils.sol","43":"node_modules/@openzeppelin/contracts/proxy/Proxy.sol","44":"node_modules/@openzeppelin/contracts/proxy/beacon/IBeacon.sol","45":"node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol","46":"node_modules/@openzeppelin/contracts/token/ERC20/IERC20.sol","47":"node_modules/@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol","48":"node_modules/@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol","49":"node_modules/@openzeppelin/contracts/utils/Address.sol","50":"node_modules/@openzeppelin/contracts/utils/Context.sol","51":"node_modules/@openzeppelin/contracts/utils/Errors.sol","52":"node_modules/@openzeppelin/contracts/utils/StorageSlot.sol","53":"node_modules/@openzeppelin/contracts/utils/introspection/IERC165.sol","54":"test/YtLending.t.sol"},"language":"Solidity"}

out/build-info/685284636136dbec.json

@@ -0,0 +1 @@
+{"id":"685284636136dbec","source_id_to_path":{"0":"contracts/ytLending/Configurator.sol","1":"contracts/ytLending/ConfiguratorStorage.sol","2":"contracts/ytLending/Lending.sol","3":"contracts/ytLending/LendingConfiguration.sol","4":"contracts/ytLending/LendingFactory.sol","5":"contracts/ytLending/LendingMath.sol","6":"contracts/ytLending/LendingStorage.sol","7":"contracts/ytLending/interfaces/ILending.sol","8":"contracts/ytLending/interfaces/IPriceFeed.sol","9":"lib/forge-std/src/Base.sol","10":"lib/forge-std/src/StdAssertions.sol","11":"lib/forge-std/src/StdChains.sol","12":"lib/forge-std/src/StdCheats.sol","13":"lib/forge-std/src/StdConstants.sol","14":"lib/forge-std/src/StdError.sol","15":"lib/forge-std/src/StdInvariant.sol","16":"lib/forge-std/src/StdJson.sol","17":"lib/forge-std/src/StdMath.sol","18":"lib/forge-std/src/StdStorage.sol","19":"lib/forge-std/src/StdStyle.sol","20":"lib/forge-std/src/StdToml.sol","21":"lib/forge-std/src/StdUtils.sol","22":"lib/forge-std/src/Test.sol","23":"lib/forge-std/src/Vm.sol","24":"lib/forge-std/src/console.sol","25":"lib/forge-std/src/console2.sol","26":"lib/forge-std/src/interfaces/IMulticall3.sol","27":"lib/forge-std/src/safeconsole.sol","28":"node_modules/@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol","29":"node_modules/@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol","30":"node_modules/@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol","31":"node_modules/@openzeppelin/contracts-upgradeable/utils/ContextUpgradeable.sol","32":"node_modules/@openzeppelin/contracts-upgradeable/utils/PausableUpgradeable.sol","33":"node_modules/@openzeppelin/contracts-upgradeable/utils/ReentrancyGuardUpgradeable.sol","34":"node_modules/@openzeppelin/contracts/access/Ownable.sol","35":"node_modules/@openzeppelin/contracts/interfaces/IERC1363.sol","36":"node_modules/@openzeppelin/contracts/interfaces/IERC165.sol","37":"node_modules/@openzeppelin/contracts/interfaces/IERC1967.sol","38":"node_modules/@openzeppelin/contracts/interfaces/IERC20.sol","39":"node_modules/@openzeppelin/contracts/interfaces/draft-IERC1822.sol","40":"node_modules/@openzeppelin/contracts/interfaces/draft-IERC6093.sol","41":"node_modules/@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol","42":"node_modules/@openzeppelin/contracts/proxy/ERC1967/ERC1967Utils.sol","43":"node_modules/@openzeppelin/contracts/proxy/Proxy.sol","44":"node_modules/@openzeppelin/contracts/proxy/beacon/IBeacon.sol","45":"node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol","46":"node_modules/@openzeppelin/contracts/token/ERC20/IERC20.sol","47":"node_modules/@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol","48":"node_modules/@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol","49":"node_modules/@openzeppelin/contracts/utils/Address.sol","50":"node_modules/@openzeppelin/contracts/utils/Context.sol","51":"node_modules/@openzeppelin/contracts/utils/Errors.sol","52":"node_modules/@openzeppelin/contracts/utils/StorageSlot.sol","53":"node_modules/@openzeppelin/contracts/utils/introspection/IERC165.sol","54":"test/YtLending.t.sol"},"language":"Solidity"}

test/YtLending.t.sol

@@ -321,15 +321,19 @@ contract YtLendingTest is Test {
         lending.accrueInterest();
         
         // 利用率 = 8000 / 10000 = 80%（在 kink 点）
-        // Supply APY = 3%（在 kink 点）
+        // Supply APY 计算：
-        // 预期余额 ≈ 10,000 * 1.03 = 10,300 USDC
+        //   rate = base + (utilization × slope)
+        //        = 0% + (80% × 3%) = 2.4%
+        // 预期余额 = 10,000 × 1.024 = 10,240 USDC
         uint256 aliceBalance = lending.balanceOf(alice);
-        assertApproxEqRel(aliceBalance, 10300e18, 0.01e18, "Alice should earn ~3% interest");
+        assertApproxEqRel(aliceBalance, 10240e18, 0.001e18, "Alice should earn 2.4% interest (0.1% tolerance)");
         
-        // Borrow APY = 1.5% + 5% = 6.5%（在 kink 点）
+        // Borrow APY 计算：
-        // 预期债务 ≈ 8,000 * 1.065 = 8,520 USDC
+        //   rate = base + (utilization × slope)
+        //        = 1.5% + (80% × 5%) = 5.5%
+        // 预期债务 = 8,000 × 1.055 = 8,440 USDC
         uint256 bobDebt = lending.borrowBalanceOf(bob);
-        assertApproxEqRel(bobDebt, 8520e18, 0.01e18, "Bob should owe ~6.5% interest");
+        assertApproxEqRel(bobDebt, 8440e18, 0.001e18, "Bob should owe 5.5% interest (0.1% tolerance)");
     }
     
     function test_11_InterestAccrual_Compound() public {
@@ -399,7 +403,52 @@ contract YtLendingTest is Test {
         assertTrue(lending.isLiquidatable(bob), "Bob should be liquidatable");
     }
     
-    function test_14_Absorb_Single() public {
+    function test_14_Liquidation_AtExactThreshold() public {
+        // 这个测试验证：在刚好达到清算线时就可以被清算
+        
+        // 0. Alice 先存入流动性
+        vm.prank(alice);
+        lending.supply(50000e18);
+        
+        // 1. Bob 建立借款头寸
+        vm.startPrank(bob);
+        lending.supplyCollateral(address(weth), 10e18);  // 10 ETH @ $2000 = $20,000
+        lending.borrow(16000e18);  // $16,000（80% LTV）
+        vm.stopPrank();
+        
+        // 2. 计算精确的清算价格
+        // 清算条件（在 Solidity 整数运算中）：
+        // debtValue > collateralValue × liquidateCollateralFactor
+        // 16000e8 > (10e18 × price_e8 / 1e18) × 0.85e18 / 1e18
+        // 16000e8 > price_e8 × 8.5
+        // price_e8 < 16000e8 / 8.5 = 188235294117.647...
+        // 安全价格：price_e8 >= 188235294118（$1,882.35294118）
+        
+        // 在清算阈值之上（安全）
+        wethPriceFeed.setPrice(1883e8);  // $1,883
+        assertFalse(lending.isLiquidatable(bob), "Bob should be safe at $1,883");
+        
+        // 接近但仍在清算阈值之上
+        wethPriceFeed.setPrice(188235294118);  // $1,882.35294118（安全临界点）
+        assertFalse(lending.isLiquidatable(bob), "Bob should be at the safe edge");
+        
+        // 刚好跌破清算阈值
+        wethPriceFeed.setPrice(188235294117);  // $1,882.35294117（危险）
+        // collateralValue = 188235294117 × 8.5 = 1,599,999,999,994.5
+        // debtValue = 16000e8 = 1,600,000,000,000
+        // 1,600,000,000,000 > 1,599,999,999,994 ✅ 可清算
+        assertTrue(lending.isLiquidatable(bob), "Bob should be liquidatable just below threshold");
+        
+        // 3. 执行清算
+        vm.prank(liquidator);
+        lending.absorb(bob);
+        
+        // 4. 验证清算成功
+        assertEq(lending.getCollateral(bob, address(weth)), 0, "Bob's collateral should be seized");
+        assertEq(lending.getCollateralReserves(address(weth)), 10e18, "Collateral should be in reserves");
+    }
+    
+    function test_15_Absorb_Single() public {
         // 0. Alice 先存入流动性
         vm.prank(alice);
         lending.supply(50000e18);
@@ -436,7 +485,7 @@ contract YtLendingTest is Test {
         assertTrue(lending.balanceOf(bob) > 0, "Bob should have positive balance from excess collateral");
     }
     
-    function test_15_AbsorbMultiple_Batch() public {
+    function test_16_AbsorbMultiple_Batch() public {
         // 0. Alice 先存入流动性
         vm.prank(alice);
         lending.supply(50000e18);
@@ -473,7 +522,7 @@ contract YtLendingTest is Test {
                         BUY COLLATERAL 测试
     //////////////////////////////////////////////////////////////*/
     
-    function test_16_BuyCollateral_Basic() public {
+    function test_17_BuyCollateral_Basic() public {
         // 0. Alice 先存入流动性
         vm.prank(alice);
         lending.supply(50000e18);
@@ -511,7 +560,7 @@ contract YtLendingTest is Test {
         assertEq(lending.getCollateralReserves(address(weth)), 0, "Collateral reserve should be empty");
     }
     
-    function test_17_BuyCollateral_WithRecipient() public {
+    function test_18_BuyCollateral_WithRecipient() public {
         // 先存入流动性
         vm.prank(owner);
         lending.supply(50000e18);
@@ -535,7 +584,7 @@ contract YtLendingTest is Test {
         assertEq(weth.balanceOf(alice), 60e18, "Alice should receive the ETH (50 + 10)");
     }
     
-    function test_18_BuyCollateral_FailWhenReserveSufficient() public {
+    function test_19_BuyCollateral_FailWhenReserveSufficient() public {
         // 这个测试验证：当 reserves >= targetReserves 时，不能购买抵押品
         // 为简化测试，我们直接验证 buyCollateral 的逻辑
         
@@ -586,12 +635,12 @@ contract YtLendingTest is Test {
                         RESERVES 测试
     //////////////////////////////////////////////////////////////*/
     
-    function test_19_GetReserves_Initial() public view {
+    function test_20_GetReserves_Initial() public view {
         // 初始储备金应该是 0
         assertEq(lending.getReserves(), 0, "Initial reserves should be 0");
     }
     
-    function test_20_GetReserves_AfterSupplyBorrow() public {
+    function test_21_GetReserves_AfterSupplyBorrow() public {
         // Alice 存入 10,000 USDC
         vm.prank(alice);
         lending.supply(10000e18);
@@ -610,7 +659,7 @@ contract YtLendingTest is Test {
         assertEq(lending.getReserves(), 0, "Reserves should still be 0");
     }
     
-    function test_21_GetReserves_WithInterest() public {
+    function test_22_GetReserves_WithInterest() public {
         // 建立借贷
         vm.prank(alice);
         lending.supply(10000e18);
@@ -625,15 +674,19 @@ contract YtLendingTest is Test {
         lending.accrueInterest();
         
         // 借款利率 > 存款利率，reserves 应该增加
-        // Borrow APY ≈ 6.5%, Supply APY ≈ 3%
+        // 利用率 = 80%（在 kink 点）
-        // 利差 ≈ 8000 * 0.065 - 10000 * 0.03 = 520 - 300 = 220
+        // Supply APY = 0% + 80% × 3% = 2.4%
-        // 由于利率是按秒计算，会有舍入误差
+        // Borrow APY = 1.5% + 80% × 5% = 5.5%
+        // 
+        // Alice 存款利息 = 10,000 × 2.4% = 240 USDC
+        // Bob 借款利息 = 8,000 × 5.5% = 440 USDC
+        // 储备金增加 = 440 - 240 = 200 USDC
         int256 reserves = lending.getReserves();
         assertTrue(reserves > 0, "Reserves should be positive from interest spread");
-        assertApproxEqRel(uint256(reserves), 220e18, 0.15e18, "Reserves should be ~220 USDC");
+        assertApproxEqRel(uint256(reserves), 200e18, 0.005e18, "Reserves should be 200 USDC (0.5% tolerance)");
     }
     
-    function test_22_WithdrawReserves_Success() public {
+    function test_23_WithdrawReserves_Success() public {
         // 1. 累积储备金
         vm.prank(alice);
         lending.supply(10000e18);
@@ -665,13 +718,13 @@ contract YtLendingTest is Test {
         );
     }
     
-    function test_23_WithdrawReserves_FailInsufficientReserves() public {
+    function test_24_WithdrawReserves_FailInsufficientReserves() public {
         // 尝试提取不存在的储备金
         vm.expectRevert(ILending.InsufficientReserves.selector);
         lending.withdrawReserves(address(0x999), 1000e18);
     }
     
-    function test_24_WithdrawReserves_FailNotOwner() public {
+    function test_25_WithdrawReserves_FailNotOwner() public {
         // 非 owner 尝试提取
         vm.prank(alice);
         vm.expectRevert();
@@ -682,7 +735,7 @@ contract YtLendingTest is Test {
                         VIEW FUNCTIONS 测试
     //////////////////////////////////////////////////////////////*/
     
-    function test_25_GetUtilization() public {
+    function test_26_GetUtilization() public {
         // 初始利用率应该是 0
         assertEq(lending.getUtilization(), 0, "Initial utilization should be 0");
         
@@ -700,7 +753,7 @@ contract YtLendingTest is Test {
         assertEq(lending.getUtilization(), 0.8e18, "Utilization should be 80%");
     }
     
-    function test_26_GetSupplyRate_BelowKink() public {
+    function test_27_GetSupplyRate_BelowKink() public {
         // 利用率 50%，低于 kink（80%）
         vm.prank(alice);
         lending.supply(10000e18);
@@ -712,12 +765,13 @@ contract YtLendingTest is Test {
         
         uint64 supplyRate = lending.getSupplyRate();
         
-        // 预期：base + 50% * slopeLow = 0 + 0.5 * 3% = 1.5% APY
+        // 预期：base + utilization × slopeLow
-        // 但是转换为每秒：1.5% / 31536000 ≈ 0.475e9
+        //     = 0% + 50% × 3% = 1.5% APY
-        assertApproxEqRel(supplyRate, 0.015e18, 0.01e18, "Supply rate should be ~1.5% APY");
+        // 这是简单计算，应该非常精确
+        assertApproxEqRel(supplyRate, 0.015e18, 0.0001e18, "Supply rate should be 1.5% APY (0.01% tolerance)");
     }
     
-    function test_27_GetBorrowRate_AtKink() public {
+    function test_28_GetBorrowRate_AtKink() public {
         // 利用率正好 80%
         vm.prank(alice);
         lending.supply(10000e18);
@@ -729,12 +783,14 @@ contract YtLendingTest is Test {
         
         uint64 borrowRate = lending.getBorrowRate();
         
-        // 预期：base + slopeLow = 1.5% + 5% = 6.5% APY
+        // 预期：base + utilization × slopeLow
-        // 实际：由于是线性插值 + 按秒计算再转年化，会有小的舍入误差
+        //     = 1.5% + 80% × 5%
-        assertApproxEqRel(borrowRate, 0.065e18, 0.2e18, "Borrow rate should be ~6.5% APY");
+        //     = 1.5% + 4% = 5.5% APY
+        // 注：getBorrowRate() 返回的是年化利率，精度很高
+        assertApproxEqRel(borrowRate, 0.055e18, 0.0001e18, "Borrow rate should be 5.5% APY (0.01% tolerance)");
     }
     
-    function test_28_QuoteCollateral() public view {
+    function test_29_QuoteCollateral() public view {
         // ETH 价格 $2000, liquidationFactor 0.95, storeFrontFactor 0.5
         // discount = 0.5 * (1 - 0.95) = 0.025 (2.5%)
         // 折扣价 = 2000 * (1 - 0.025) = $1,950
@@ -750,7 +806,7 @@ contract YtLendingTest is Test {
                         EDGE CASES 测试
     //////////////////////////////////////////////////////////////*/
     
-    function test_29_Borrow_MaxLTV() public {
+    function test_30_Borrow_MaxLTV() public {
         // Bob 先存入流动性
         vm.prank(bob);
         lending.supply(50000e18);
@@ -767,7 +823,7 @@ contract YtLendingTest is Test {
         vm.stopPrank();
     }
     
-    function test_30_Borrow_FailOverLTV() public {
+    function test_31_Borrow_FailOverLTV() public {
         // Bob 先存入流动性
         vm.prank(bob);
         lending.supply(50000e18);
@@ -782,7 +838,7 @@ contract YtLendingTest is Test {
         vm.stopPrank();
     }
     
-    function test_31_WithdrawCollateral_FailIfBorrowing() public {
+    function test_32_WithdrawCollateral_FailIfBorrowing() public {
         // Bob 先存入流动性
         vm.prank(bob);
         lending.supply(50000e18);
@@ -798,7 +854,7 @@ contract YtLendingTest is Test {
         vm.stopPrank();
     }
     
-    function test_32_SupplyCollateral_FailExceedCap() public {
+    function test_33_SupplyCollateral_FailExceedCap() public {
         // 尝试超过供应上限（100,000 ETH）
         weth.mint(alice, 200000e18);
         
@@ -808,7 +864,7 @@ contract YtLendingTest is Test {
         vm.stopPrank();
     }
     
-    function test_33_ComplexScenario_MultipleUsers() public {
+    function test_34_ComplexScenario_MultipleUsers() public {
         // 1. Alice 存款
         vm.prank(alice);
         lending.supply(50000e18);