[main][fix] LibShareUtil rounding

solidity/contracts/money-market/libraries/LibShareUtil.sol

@@ -33,7 +33,8 @@ library LibShareUtil {
   ) internal pure returns (uint256) {
     uint256 _shares = valueToShare(_tokenAmount, _totalShare, _totalValue);
     uint256 _shareValues = shareToValue(_shares, _totalValue, _totalShare);
-    if (_shareValues + 1 == _tokenAmount) {
+
+    if (_shareValues + 1 <= _tokenAmount) {
       _shares += 1;
     }
     return _shares;
@@ -46,7 +47,7 @@ library LibShareUtil {
   ) internal pure returns (uint256) {
     uint256 _values = shareToValue(_shareAmount, _totalValue, _totalShare);
     uint256 _valueShares = valueToShare(_values, _totalShare, _totalValue);
-    if (_valueShares + 1 == _shareAmount) {
+    if (_valueShares + 1 <= _shareAmount) {
       _values += 1;
     }
     return _values;

solidity/tests/money-market/MoneyMarket_BaseTest.t.sol

@@ -19,6 +19,8 @@ import { IMMOwnershipFacet } from "../../contracts/money-market/interfaces/IMMOw
 import { IMoneyMarketAccountManager } from "../../contracts/interfaces/IMoneyMarketAccountManager.sol";
 import { IFlashloanFacet } from "../../contracts/money-market/interfaces/IFlashloanFacet.sol";
 import { IERC20 } from "../../contracts/money-market/interfaces/IERC20.sol";
+import { TestHelperFacet } from "solidity/tests/money-market/utils/TestHelperFacet.sol";
+import { IMMDiamondCut } from "solidity/contracts/money-market/interfaces/IMMDiamondCut.sol";
 
 // mocks
 import { MockERC20 } from "../mocks/MockERC20.sol";
@@ -46,6 +48,8 @@ abstract contract MoneyMarket_BaseTest is BaseTest {
   ILiquidationFacet internal liquidationFacet;
   IMMOwnershipFacet internal MMOwnershipFacet;
   IFlashloanFacet internal flashloanFacet;
+  // helper facet for test only
+  TestHelperFacet internal testHelperFacet;
 
   MockAlpacaV2Oracle internal mockOracle;
 
@@ -64,6 +68,10 @@ abstract contract MoneyMarket_BaseTest is BaseTest {
     MMOwnershipFacet = IMMOwnershipFacet(moneyMarketDiamond);
     flashloanFacet = IFlashloanFacet(moneyMarketDiamond);
 
+    //
+    setUpTestHelperFacet();
+    testHelperFacet = TestHelperFacet(moneyMarketDiamond);
+
     address[] memory _whitelistedCallers = new address[](1);
     _whitelistedCallers[0] = moneyMarketDiamond;
     miniFL.setWhitelistedCallers(_whitelistedCallers, true);
@@ -237,4 +245,23 @@ abstract contract MoneyMarket_BaseTest is BaseTest {
     // set minimum debt required to borrow
     adminFacet.setMinDebtSize(normalizeEther(0.1 ether, usdDecimal));
   }
+
+  function setUpTestHelperFacet() internal {
+    TestHelperFacet _testHelperFacet = new TestHelperFacet();
+    //
+    bytes4[] memory _selectors = new bytes4[](2);
+    _selectors[0] = TestHelperFacet.writeGlobalDebts.selector;
+    _selectors[1] = TestHelperFacet.writeoverCollatDebtValues.selector;
+
+    //
+    IMMDiamondCut.FacetCut[] memory _facetCuts = new IMMDiamondCut.FacetCut[](1);
+
+    _facetCuts[0] = IMMDiamondCut.FacetCut({
+      action: IMMDiamondCut.FacetCutAction.Add,
+      facetAddress: address(_testHelperFacet),
+      functionSelectors: _selectors
+    });
+
+    IMMDiamondCut(moneyMarketDiamond).diamondCut(_facetCuts, address(0), "");
+  }
 }

solidity/tests/money-market/over-collat/MoneyMarket_OverCollatBorrow_Borrow.t.sol

@@ -2,6 +2,7 @@
 pragma solidity 0.8.19;
 
 import { MoneyMarket_BaseTest, MockERC20, console } from "../MoneyMarket_BaseTest.t.sol";
+import { FixedInterestRateModel, IInterestRateModel } from "../../../contracts/money-market/interest-models/FixedInterestRateModel.sol";
 
 // libraries
 import { LibMoneyMarket01 } from "../../../contracts/money-market/libraries/LibMoneyMarket01.sol";
@@ -416,7 +417,7 @@ contract MoneyMarket_OverCollatBorrow_BorrowTest is MoneyMarket_BaseTest {
     assertEq(_miniFL.getUserTotalAmountOf(_poolId, BOB), _borrowAmount);
   }
 
-  function testRevert_WhenDemoteMarket_UserHasMoreThanOneIsolate_ShouldNotBeAbleToBorrow() public {
+  function testRevert_WhenDemoteMarket_UserHasMoreThanOneIsolate_ShouldNotBeAbleToBorrow() external {
     // prepare
     usdc.mint(ALICE, 1e10);
     vm.prank(ALICE);
@@ -472,4 +473,60 @@ contract MoneyMarket_OverCollatBorrow_BorrowTest is MoneyMarket_BaseTest {
     vm.expectRevert(abi.encodeWithSelector(IBorrowFacet.BorrowFacet_InvalidAssetTier.selector));
     accountManager.borrow(subAccount0, address(btc), 0.01 ether);
   }
+
+  function testCorrectness_WhenUerBorrowTokenFromMM_WithShareValueMoreThanTwo_MMShouldCalculateShareToAddCorrectly()
+    external
+  {
+    FixedInterestRateModel model = new FixedInterestRateModel(wethDecimal);
+    adminFacet.setInterestModel(address(weth), address(model));
+
+    deal(address(weth), ALICE, 20 ether);
+    vm.startPrank(ALICE);
+    // just add collateral for borrowing power
+    accountManager.addCollateralFor(ALICE, subAccount0, address(weth), normalizeEther(10 ether, wethDecimal));
+    accountManager.addCollateralFor(BOB, subAccount0, address(weth), normalizeEther(10 ether, wethDecimal));
+
+    uint256 _borrowAmount = 1.000000000000000001 ether;
+
+    accountManager.borrow(subAccount0, address(weth), normalizeEther(_borrowAmount, wethDecimal));
+
+    vm.startPrank(moneyMarketDiamond);
+
+    // fabricate contract state for assertion
+    vm.warp(block.timestamp + 1000);
+    borrowFacet.accrueInterest(address(weth));
+    testHelperFacet.writeGlobalDebts(address(weth), 2 ether);
+    testHelperFacet.writeoverCollatDebtValues(address(weth), 2 ether);
+
+    uint256 wethGlobalDebt = viewFacet.getGlobalDebtValue(address(weth));
+
+    assertEq(wethGlobalDebt, 2 ether);
+
+    (uint256 _aliceDebtShare, uint256 _aliceDebtAmount) = viewFacet.getOverCollatDebtShareAndAmountOf(
+      ALICE,
+      subAccount0,
+      address(weth)
+    );
+
+    vm.stopPrank();
+
+    vm.startPrank(BOB);
+
+    accountManager.borrow(subAccount0, address(weth), normalizeEther(1.000000000000000002 ether, wethDecimal));
+
+    // shares = amount * share / totalDebtValue = 1.000000000000000002 * 1.000000000000000001 / 2.000000000000000000 = 0.500000000000000001
+    // sharesValue = _shares * _totalValue / _totalShare =  0.500000000000000001 * 2.000000000000000000 / 1.000000000000000001 = 1.000000000000000000
+    // sharesValue + 1 <= _tokenAmount = 1.000000000000000000 + 1 <= 1.000000000000000002
+    // _shares = _shares+1 = 0.500000000000000001 + 1 = 0.500000000000000002
+    (uint256 _bobDebtShare, uint256 _bobDebtAmount) = viewFacet.getOverCollatDebtShareAndAmountOf(
+      BOB,
+      subAccount0,
+      address(weth)
+    );
+
+    assertEq(_bobDebtShare, 0.500000000000000002 ether);
+    assertEq(_bobDebtAmount, 1.000000000000000002 ether);
+
+    vm.stopPrank();
+  }
 }

solidity/tests/money-market/utils/TestHelperFacet.sol

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.19;
+
+import { LibMoneyMarket01 } from "solidity/contracts/money-market/libraries/LibMoneyMarket01.sol";
+
+/// @title A HelperFacet for faciliating test
+contract TestHelperFacet {
+  function writeGlobalDebts(address _token, uint256 _newAmount) public {
+    LibMoneyMarket01.MoneyMarketDiamondStorage storage moneyMarketDs = LibMoneyMarket01.moneyMarketDiamondStorage();
+
+    moneyMarketDs.globalDebts[_token] = _newAmount;
+  }
+
+  function writeoverCollatDebtValues(address _token, uint256 _newAmount) public {
+    LibMoneyMarket01.MoneyMarketDiamondStorage storage moneyMarketDs = LibMoneyMarket01.moneyMarketDiamondStorage();
+
+    moneyMarketDs.overCollatDebtValues[_token] = _newAmount;
+  }
+}