Merge pull request #18 from risedle/audit-rev

✦ Subsquent addSupply

src/RisedleVault.sol

@@ -208,10 +208,10 @@ contract RisedleVault is ERC20, Ownable, ReentrancyGuard {
     /// @notice Lender supplies underlying token into the vault and receives vault tokens in exchange
     function addSupply(uint256 amount) external nonReentrant {
         accrueInterest(); // Accrue interest
-        if (maxTotalDeposit != 0) require(IERC20(underlyingToken).balanceOf(address(this)) + amount < maxTotalDeposit, "!MCR"); // Max cap reached
-        IERC20(underlyingToken).safeTransferFrom(msg.sender, address(this), amount); // Transfer asset from lender to the vault
+        if (maxTotalDeposit != 0) require(getTotalAvailableCash() + totalOutstandingDebt + amount < maxTotalDeposit, "!MCR"); // Max cap reached
         uint256 exchangeRateInEther = getExchangeRateInEther(); // Get the exchange rate
         uint256 mintedAmount = (amount * 1 ether) / exchangeRateInEther; // Calculate how much vault token we need to send to the lender
+        IERC20(underlyingToken).safeTransferFrom(msg.sender, address(this), amount); // Transfer asset from lender to the vault
         _mint(msg.sender, mintedAmount); // Send vault token to the lender
         emit SupplyAdded(msg.sender, amount, exchangeRateInEther, mintedAmount);
     }

src/test/RisedleVaultExternal.t.sol

@@ -117,6 +117,36 @@ contract RisedleVaultExternalTest is DSTest {
         assertEq(vault.getExchangeRateInEther(), 1 ether);
     }
 
+    /// @notice Make sure subsquent supply yield the same amount of rvToken
+    function test_SubsequentSupplyToTheVault() public {
+        // Create new vault
+        RisedleVault vault = createNewVault();
+
+        // Create new lender
+        Lender lender = new Lender(vault);
+
+        // Set the lender USDC balance
+        uint256 amount = 1000 * 1e6; // 1000 USDC
+        hevm.setUSDCBalance(address(lender), amount);
+
+        // Lender add supply to the vault
+        uint256 depositAmount = 500 * 1e6;
+        lender.lend(depositAmount); // 500 USDC first
+
+        // Lender should receive the same amount of vault token
+        // Because the initial exchange rate is 1:1
+        uint256 lenderVaultTokenBalance = vault.balanceOf(address(lender));
+        assertEq(lenderVaultTokenBalance, depositAmount);
+
+        // The vault should receive the USDC
+        assertEq(IERC20(USDC_ADDRESS).balanceOf(address(vault)), depositAmount);
+
+        // Lender add supply once again
+        lender.lend(depositAmount); // 500 USDC second
+        assertEq(vault.balanceOf(address(lender)), depositAmount * 2);
+        assertEq(IERC20(USDC_ADDRESS).balanceOf(address(vault)), depositAmount * 2);
+    }
+
     /// @notice Make sure anyone can remove asset from the vault
     function test_AnyoneCanRemoveSupplyFromTheVault() public {
         // Create new vault