Merge branch 'fix/23' into 'master'

Resolve "FlashLoans V2"

Closes #23

See merge request aave-tech/protocol-v2!30

contracts/flashloan/base/FlashLoanReceiverBase.sol

@@ -12,27 +12,12 @@ abstract contract FlashLoanReceiverBase is IFlashLoanReceiver {
   using SafeERC20 for IERC20;
   using SafeMath for uint256;
 
-  ILendingPoolAddressesProvider public addressesProvider;
+  ILendingPoolAddressesProvider internal _addressesProvider;
 
   constructor(ILendingPoolAddressesProvider provider) public {
-    addressesProvider = provider;
+    _addressesProvider = provider;
   }
 
   receive() external payable {}
 
-  function _transferFundsBack(
-    address reserve,
-    address destination,
-    uint256 amount
-  ) internal {
-    transferInternal(destination, reserve, amount);
-  }
-
-  function transferInternal(
-    address destination,
-    address reserve,
-    uint256 amount
-  ) internal {
-    IERC20(reserve).safeTransfer(destination, amount);
-  }
 }

contracts/flashloan/interfaces/IFlashLoanReceiver.sol

@@ -10,7 +10,6 @@ pragma solidity ^0.6.8;
 interface IFlashLoanReceiver {
   function executeOperation(
     address reserve,
-    address destination,
     uint256 amount,
     uint256 fee,
     bytes calldata params

contracts/interfaces/ILendingPool.sol

@@ -63,7 +63,7 @@ interface ILendingPool {
    * @param reserve the address of the reserve
    * @param user the address of the user executing the swap
    **/
-  event Swap(address indexed reserve, address indexed user, uint256 timestamp);
+  event Swap(address indexed reserve, address indexed user);
 
   /**
    * @dev emitted when a user enables a reserve as collateral
@@ -90,13 +90,15 @@ interface ILendingPool {
    * @param target the address of the flashLoanReceiver
    * @param reserve the address of the reserve
    * @param amount the amount requested
-   * @param totalFee the total fee on the amount
+   * @param totalPremium the total fee on the amount
+   * @param referralCode the referral code of the caller
    **/
   event FlashLoan(
     address indexed target,
     address indexed reserve,
     uint256 amount,
-    uint256 totalFee
+    uint256 totalPremium,
+    uint16 referralCode
   );
   /**
    * @dev these events are not emitted directly by the LendingPool
@@ -105,21 +107,6 @@ interface ILendingPool {
    * This allows to have the events in the generated ABI for LendingPool.
    **/
 
-  /**
-   * @dev emitted when a borrow fee is liquidated
-   * @param collateral the address of the collateral being liquidated
-   * @param reserve the address of the reserve
-   * @param user the address of the user being liquidated
-   * @param feeLiquidated the total fee liquidated
-   * @param liquidatedCollateralForFee the amount of collateral received by the protocol in exchange for the fee
-   **/
-  event OriginationFeeLiquidated(
-    address indexed collateral,
-    address indexed reserve,
-    address indexed user,
-    uint256 feeLiquidated,
-    uint256 liquidatedCollateralForFee
-  );
   /**
    * @dev emitted when a borrower is liquidated
    * @param collateral the address of the collateral being liquidated
@@ -238,12 +225,16 @@ interface ILendingPool {
    * @param receiver The address of the contract receiving the funds. The receiver should implement the IFlashLoanReceiver interface.
    * @param reserve the address of the principal reserve
    * @param amount the amount requested for this flashloan
+   * @param params a bytes array to be sent to the flashloan executor
+   * @param referralCode the referral code of the caller
    **/
   function flashLoan(
     address receiver,
     address reserve,
     uint256 amount,
-    bytes calldata params
+    uint256 debtType,
+    bytes calldata params,
+    uint16 referralCode
   ) external;
 
   /**

contracts/lendingpool/LendingPool.sol

@@ -3,7 +3,6 @@ pragma solidity ^0.6.8;
 pragma experimental ABIEncoderV2;
 
 import {SafeMath} from '@openzeppelin/contracts/math/SafeMath.sol';
-import {ReentrancyGuard} from '@openzeppelin/contracts/utils/ReentrancyGuard.sol';
 import {IERC20} from '@openzeppelin/contracts/token/ERC20/IERC20.sol';
 import {
   VersionedInitializable
@@ -32,7 +31,7 @@ import {ILendingPool} from '../interfaces/ILendingPool.sol';
  * @author Aave
  **/
 
-contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
+contract LendingPool is VersionedInitializable, ILendingPool {
   using SafeMath for uint256;
   using WadRayMath for uint256;
   using ReserveLogic for ReserveLogic.ReserveData;
@@ -43,7 +42,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
   //main configuration parameters
   uint256 public constant REBALANCE_DOWN_RATE_DELTA = (1e27) / 5;
   uint256 public constant MAX_STABLE_RATE_BORROW_SIZE_PERCENT = 25;
-  uint256 public constant FLASHLOAN_FEE_TOTAL = 9;
+  uint256 public constant FLASHLOAN_PREMIUM_TOTAL = 9;
 
   ILendingPoolAddressesProvider internal _addressesProvider;
 
@@ -91,7 +90,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
     address asset,
     uint256 amount,
     uint16 referralCode
-  ) external override nonReentrant {
+  ) external override {
     ReserveLogic.ReserveData storage reserve = _reserves[asset];
 
     ValidationLogic.validateDeposit(reserve, amount);
@@ -112,7 +111,6 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
     //transfer to the aToken contract
     IERC20(asset).safeTransferFrom(msg.sender, aToken, amount);
 
-    //solium-disable-next-line
     emit Deposit(asset, msg.sender, amount, referralCode);
   }
 
@@ -121,7 +119,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
    * @param asset the address of the reserve
    * @param amount the underlying amount to be redeemed
    **/
-  function withdraw(address asset, uint256 amount) external override nonReentrant {
+  function withdraw(address asset, uint256 amount) external override {
     ReserveLogic.ReserveData storage reserve = _reserves[asset];
 
     address aToken = reserve.aTokenAddress;
@@ -156,7 +154,6 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
 
     IAToken(aToken).burn(msg.sender, msg.sender, amountToWithdraw);
 
-    //solium-disable-next-line
     emit Withdraw(asset, msg.sender, amount);
   }
 
@@ -166,65 +163,24 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
    * @param asset the address of the reserve
    * @param amount the amount to be borrowed
    * @param interestRateMode the interest rate mode at which the user wants to borrow. Can be 0 (STABLE) or 1 (VARIABLE)
+   * @param referralCode a referral code for integrators
    **/
   function borrow(
     address asset,
     uint256 amount,
     uint256 interestRateMode,
     uint16 referralCode
-  ) external override nonReentrant {
+  ) external override {
-    ReserveLogic.ReserveData storage reserve = _reserves[asset];
+    _executeBorrow(
-    UserConfiguration.Map storage userConfig = _usersConfig[msg.sender];
+      ExecuteBorrowParams(
-
+        asset,
-    uint256 amountInETH = IPriceOracleGetter(_addressesProvider.getPriceOracle())
+        msg.sender,
-      .getAssetPrice(asset)
+        amount,
-      .mul(amount)
+        interestRateMode,
-      .div(10**reserve.configuration.getDecimals()); //price is in ether
+        _reserves[asset].aTokenAddress,
-
+        referralCode,
-    ValidationLogic.validateBorrow(
+        true
-      reserve,
+      )
-      asset,
-      amount,
-      amountInETH,
-      interestRateMode,
-      MAX_STABLE_RATE_BORROW_SIZE_PERCENT,
-      _reserves,
-      _usersConfig[msg.sender],
-      _reservesList,
-      _addressesProvider.getPriceOracle()
-    );
-
-    //caching the current stable borrow rate
-    uint256 userStableRate = reserve.currentStableBorrowRate;
-
-    reserve.updateCumulativeIndexesAndTimestamp();
-
-    if (ReserveLogic.InterestRateMode(interestRateMode) == ReserveLogic.InterestRateMode.STABLE) {
-      IStableDebtToken(reserve.stableDebtTokenAddress).mint(msg.sender, amount, userStableRate);
-    } else {
-      IVariableDebtToken(reserve.variableDebtTokenAddress).mint(msg.sender, amount);
-    }
-
-    address aToken = reserve.aTokenAddress;
-    reserve.updateInterestRates(asset, aToken, 0, amount);
-
-    uint256 reserveIndex = reserve.index;
-    if (!userConfig.isBorrowing(reserveIndex)) {
-      userConfig.setBorrowing(reserveIndex, true);
-    }
-
-    //if we reached this point, we can transfer
-    IAToken(aToken).transferUnderlyingTo(msg.sender, amount);
-
-    emit Borrow(
-      asset,
-      msg.sender,
-      amount,
-      interestRateMode,
-      ReserveLogic.InterestRateMode(interestRateMode) == ReserveLogic.InterestRateMode.STABLE
-        ? userStableRate
-        : reserve.currentVariableBorrowRate,
-      referralCode
     );
   }
 
@@ -241,7 +197,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
     uint256 amount,
     uint256 rateMode,
     address onBehalfOf
-  ) external override nonReentrant {
+  ) external override {
     ReserveLogic.ReserveData storage reserve = _reserves[asset];
 
     (uint256 stableDebt, uint256 variableDebt) = Helpers.getUserCurrentDebt(onBehalfOf, reserve);
@@ -292,7 +248,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
    * @param asset the address of the reserve on which the user borrowed
    * @param rateMode the rate mode that the user wants to swap
    **/
-  function swapBorrowRateMode(address asset, uint256 rateMode) external override nonReentrant {
+  function swapBorrowRateMode(address asset, uint256 rateMode) external override {
     ReserveLogic.ReserveData storage reserve = _reserves[asset];
 
     (uint256 stableDebt, uint256 variableDebt) = Helpers.getUserCurrentDebt(msg.sender, reserve);
@@ -325,12 +281,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
 
     reserve.updateInterestRates(asset, reserve.aTokenAddress, 0, 0);
 
-    emit Swap(
+    emit Swap(asset, msg.sender);
-      asset,
-      msg.sender,
-      //solium-disable-next-line
-      block.timestamp
-    );
   }
 
   /**
@@ -340,7 +291,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
    * @param asset the address of the reserve
    * @param user the address of the user to be rebalanced
    **/
-  function rebalanceStableBorrowRate(address asset, address user) external override nonReentrant {
+  function rebalanceStableBorrowRate(address asset, address user) external override {
     ReserveLogic.ReserveData storage reserve = _reserves[asset];
 
     IStableDebtToken stableDebtToken = IStableDebtToken(reserve.stableDebtTokenAddress);
@@ -385,11 +336,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
    * @param asset the address of the reserve
    * @param useAsCollateral true if the user wants to user the deposit as collateral, false otherwise.
    **/
-  function setUserUseReserveAsCollateral(address asset, bool useAsCollateral)
+  function setUserUseReserveAsCollateral(address asset, bool useAsCollateral) external override {
-    external
-    override
-    nonReentrant
-  {
     ReserveLogic.ReserveData storage reserve = _reserves[asset];
 
     ValidationLogic.validateSetUseReserveAsCollateral(
@@ -425,7 +372,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
     address user,
     uint256 purchaseAmount,
     bool receiveAToken
-  ) external override nonReentrant {
+  ) external override {
     address liquidationManager = _addressesProvider.getLendingPoolLiquidationManager();
 
     //solium-disable-next-line
@@ -449,65 +396,83 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
     }
   }
 
+  struct FlashLoanLocalVars {
+    uint256 premium;
+    uint256 amountPlusPremium;
+    uint256 amountPlusPremiumInETH;
+    uint256 receiverBalance;
+    uint256 receiverAllowance;
+    uint256 availableBalance;
+    uint256 assetPrice;
+    IFlashLoanReceiver receiver;
+    address aTokenAddress;
+    address oracle;
+  }
+
   /**
-   * @dev allows smartcontracts to access the liquidity of the pool within one transaction,
+   * @dev allows smart contracts to access the liquidity of the pool within one transaction,
    * as long as the amount taken plus a fee is returned. NOTE There are security concerns for developers of flashloan receiver contracts
    * that must be kept into consideration. For further details please visit https://developers.aave.com
    * @param receiverAddress The address of the contract receiving the funds. The receiver should implement the IFlashLoanReceiver interface.
-   * @param asset the address of the principal reserve
+   * @param asset The address of the principal reserve
-   * @param amount the amount requested for this flashloan
+   * @param amount The amount requested for this flashloan
+   * @param mode Type of the debt to open if the flash loan is not returned. 0 -> Don't open any debt, just revert, 1 -> stable, 2 -> variable
+   * @param params Variadic packed params to pass to the receiver as extra information
+   * @param referralCode Referral code of the flash loan
    **/
   function flashLoan(
     address receiverAddress,
     address asset,
     uint256 amount,
-    bytes calldata params
+    uint256 mode,
-  ) external override nonReentrant {
+    bytes calldata params,
+    uint16 referralCode
+  ) external override {
     ReserveLogic.ReserveData storage reserve = _reserves[asset];
+    FlashLoanLocalVars memory vars;
 
-    address aTokenAddress = reserve.aTokenAddress;
+    vars.aTokenAddress = reserve.aTokenAddress;
 
-    //check that the reserve has enough available liquidity
+    vars.premium = amount.mul(FLASHLOAN_PREMIUM_TOTAL).div(10000);
-    uint256 availableLiquidityBefore = IERC20(asset).balanceOf(aTokenAddress);
 
-    //calculate amount fee
+    ValidationLogic.validateFlashloan(mode, vars.premium);
-    uint256 amountFee = amount.mul(FLASHLOAN_FEE_TOTAL).div(10000);
 
-    require(availableLiquidityBefore >= amount, Errors.NOT_ENOUGH_LIQUIDITY_TO_BORROW);
+    ReserveLogic.InterestRateMode debtMode = ReserveLogic.InterestRateMode(mode);
-    require(amountFee > 0, Errors.REQUESTED_AMOUNT_TOO_SMALL);
 
-    //get the FlashLoanReceiver instance
+    vars.receiver = IFlashLoanReceiver(receiverAddress);
-    IFlashLoanReceiver receiver = IFlashLoanReceiver(receiverAddress);
 
     //transfer funds to the receiver
-    IAToken(aTokenAddress).transferUnderlyingTo(receiverAddress, amount);
+    IAToken(vars.aTokenAddress).transferUnderlyingTo(receiverAddress, amount);
 
     //execute action of the receiver
-    receiver.executeOperation(asset, aTokenAddress, amount, amountFee, params);
+    vars.receiver.executeOperation(asset, amount, vars.premium, params);
 
-    //check that the actual balance of the core contract includes the returned amount
+    vars.amountPlusPremium = amount.add(vars.premium);
-    uint256 availableLiquidityAfter = IERC20(asset).balanceOf(aTokenAddress);
 
-    require(
+    if (debtMode == ReserveLogic.InterestRateMode.NONE) {
-      availableLiquidityAfter == availableLiquidityBefore.add(amountFee),
+      
-      Errors.INCONSISTENT_PROTOCOL_ACTUAL_BALANCE
+      IERC20(asset).transferFrom(receiverAddress, vars.aTokenAddress, vars.amountPlusPremium);
-    );
+      
+      reserve.updateCumulativeIndexesAndTimestamp();
+      reserve.cumulateToLiquidityIndex(IERC20(vars.aTokenAddress).totalSupply(), vars.premium);
+      reserve.updateInterestRates(asset, vars.aTokenAddress, vars.premium, 0);
+      
+      emit FlashLoan(receiverAddress, asset, amount, vars.premium, referralCode);
 
-    //compounding the cumulated interest
+    } else {
-    reserve.updateCumulativeIndexesAndTimestamp();
+      // If the transfer didn't succeed, the receiver either didn't return the funds, or didn't approve the transfer.
-
+      _executeBorrow(
-    uint256 totalLiquidityBefore = availableLiquidityBefore
+        ExecuteBorrowParams(
-      .add(IERC20(reserve.variableDebtTokenAddress).totalSupply())
+          asset,
-      .add(IERC20(reserve.stableDebtTokenAddress).totalSupply());
+          msg.sender,
-
+          vars.amountPlusPremium.sub(vars.availableBalance),
-    //compounding the received fee into the reserve
+          mode,
-    reserve.cumulateToLiquidityIndex(totalLiquidityBefore, amountFee);
+          vars.aTokenAddress,
-
+          referralCode,
-    //refresh interest rates
+          false
-    reserve.updateInterestRates(asset, aTokenAddress, amountFee, 0);
+        )
-
+      );
-    //solium-disable-next-line
+    }
-    emit FlashLoan(receiverAddress, asset, amount, amountFee);
   }
 
   /**
@@ -724,9 +689,89 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable, ILendingPool {
     return _reserves[asset].configuration;
   }
 
+  // internal functions
+
+  struct ExecuteBorrowParams {
+    address asset;
+    address user;
+    uint256 amount;
+    uint256 interestRateMode;
+    address aTokenAddress;
+    uint16 referralCode;
+    bool releaseUnderlying;
+  }
+
   /**
-   * @notice internal functions
+   * @dev Internal function to execute a borrowing action, allowing to transfer or not the underlying
+   * @param vars Input struct for the borrowing action, in order to avoid STD errors
    **/
+  function _executeBorrow(ExecuteBorrowParams memory vars) internal {
+    ReserveLogic.ReserveData storage reserve = _reserves[vars.asset];
+    UserConfiguration.Map storage userConfig = _usersConfig[msg.sender];
+
+    address oracle = _addressesProvider.getPriceOracle();
+
+    uint256 amountInETH = IPriceOracleGetter(oracle).getAssetPrice(vars.asset).mul(vars.amount).div(
+      10**reserve.configuration.getDecimals()
+    );
+
+    ValidationLogic.validateBorrow(
+      reserve,
+      vars.asset,
+      vars.amount,
+      amountInETH,
+      vars.interestRateMode,
+      MAX_STABLE_RATE_BORROW_SIZE_PERCENT,
+      _reserves,
+      userConfig,
+      _reservesList,
+      oracle
+    );
+
+
+    uint256 reserveIndex = reserve.index;
+    if (!userConfig.isBorrowing(reserveIndex)) {
+      userConfig.setBorrowing(reserveIndex, true);
+    }
+
+
+    reserve.updateCumulativeIndexesAndTimestamp();
+
+    //caching the current stable borrow rate
+    uint256 currentStableRate = 0;
+
+    if (
+      ReserveLogic.InterestRateMode(vars.interestRateMode) == ReserveLogic.InterestRateMode.STABLE
+    ) {
+      currentStableRate = reserve.currentStableBorrowRate;
+
+      IStableDebtToken(reserve.stableDebtTokenAddress).mint(
+        vars.user,
+        vars.amount,
+        currentStableRate
+      );
+    } else {
+      IVariableDebtToken(reserve.variableDebtTokenAddress).mint(vars.user, vars.amount);
+    }
+
+    reserve.updateInterestRates(vars.asset, vars.aTokenAddress, 0, vars.releaseUnderlying ?  vars.amount : 0);
+  
+    if(vars.releaseUnderlying){
+        IAToken(vars.aTokenAddress).transferUnderlyingTo(msg.sender, vars.amount);
+    }
+  
+  
+    emit Borrow(
+      vars.asset,
+      msg.sender,
+      vars.amount,
+      vars.interestRateMode,
+      ReserveLogic.InterestRateMode(vars.interestRateMode) == ReserveLogic.InterestRateMode.STABLE
+        ? currentStableRate
+        : reserve.currentVariableBorrowRate,
+      vars.referralCode
+    );
+  }
 
   /**
    * @dev adds a reserve to the array of the _reserves address

contracts/lendingpool/LendingPoolLiquidationManager.sol

@@ -3,8 +3,6 @@ pragma solidity ^0.6.8;
 
 import {SafeMath} from '@openzeppelin/contracts/math/SafeMath.sol';
 import {IERC20} from '@openzeppelin/contracts/token/ERC20/IERC20.sol';
-import {ReentrancyGuard} from '@openzeppelin/contracts/utils/ReentrancyGuard.sol';
-import {ReentrancyGuard} from '@openzeppelin/contracts/utils/ReentrancyGuard.sol';
 import {
   VersionedInitializable
 } from '../libraries/openzeppelin-upgradeability/VersionedInitializable.sol';
@@ -28,7 +26,7 @@ import {Errors} from '../libraries/helpers/Errors.sol';
  * @author Aave
  * @notice Implements the liquidation function.
  **/
-contract LendingPoolLiquidationManager is ReentrancyGuard, VersionedInitializable {
+contract LendingPoolLiquidationManager is VersionedInitializable {
   using SafeERC20 for IERC20;
   using SafeMath for uint256;
   using WadRayMath for uint256;

contracts/libraries/helpers/Errors.sol

@@ -62,4 +62,5 @@ library Errors {
   string public constant SPECIFIED_CURRENCY_NOT_BORROWED_BY_USER = '40'; // 'User did not borrow the specified currency'
   string public constant NOT_ENOUGH_LIQUIDITY_TO_LIQUIDATE = '41'; // "There isn't enough liquidity available to liquidate"
   string public constant NO_ERRORS = '42'; // 'No errors'
+  string public constant INVALID_FLASHLOAN_MODE = '43'; //Invalid flashloan mode selected
 }

contracts/libraries/logic/ValidationLogic.sol

@@ -60,10 +60,6 @@ library ValidationLogic {
   ) external view {
     require(amount > 0, Errors.AMOUNT_NOT_GREATER_THAN_0);
 
-    uint256 currentAvailableLiquidity = IERC20(reserveAddress).balanceOf(address(aTokenAddress));
-
-    require(currentAvailableLiquidity >= amount, Errors.CURRENT_AVAILABLE_LIQUIDITY_NOT_ENOUGH);
-
     require(amount <= userBalance, Errors.NOT_ENOUGH_AVAILABLE_USER_BALANCE);
 
     require(
@@ -148,11 +144,6 @@ library ValidationLogic {
       Errors.INVALID_INTEREST_RATE_MODE_SELECTED
     );
 
-    //check that the amount is available in the reserve
-    vars.availableLiquidity = IERC20(reserveAddress).balanceOf(address(reserve.aTokenAddress));
-
-    require(vars.availableLiquidity >= amount, Errors.CURRENT_AVAILABLE_LIQUIDITY_NOT_ENOUGH);
-
     (
       vars.userCollateralBalanceETH,
       vars.userBorrowBalanceETH,
@@ -328,4 +319,14 @@ library ValidationLogic {
       Errors.DEPOSIT_ALREADY_IN_USE
     );
   }
+
+  /**
+  * @dev validates a flashloan action
+  * @param mode the flashloan mode (0 = classic flashloan, 1 = open a stable rate loan, 2 = open a variable rate loan)
+  * @param premium the premium paid on the flashloan
+  **/
+  function validateFlashloan(uint256 mode, uint256 premium) internal pure {
+    require(premium > 0, Errors.REQUESTED_AMOUNT_TOO_SMALL);
+    require(mode <= uint256(ReserveLogic.InterestRateMode.VARIABLE), Errors.INVALID_FLASHLOAN_MODE);
+  }
 }

contracts/mocks/flashloan/MockFlashLoanReceiver.sol

@@ -13,46 +13,54 @@ contract MockFlashLoanReceiver is FlashLoanReceiverBase {
   using SafeMath for uint256;
   using SafeERC20 for IERC20;
 
+  ILendingPoolAddressesProvider internal _provider;
+
   event ExecutedWithFail(address _reserve, uint256 _amount, uint256 _fee);
   event ExecutedWithSuccess(address _reserve, uint256 _amount, uint256 _fee);
 
-  bool failExecution = false;
+  bool _failExecution;
+  uint256 _amountToApprove;
 
-  constructor(ILendingPoolAddressesProvider _provider) public FlashLoanReceiverBase(_provider) {}
+  constructor(ILendingPoolAddressesProvider provider) public FlashLoanReceiverBase(provider) {}
 
-  function setFailExecutionTransfer(bool _fail) public {
+  function setFailExecutionTransfer(bool fail) public {
-    failExecution = _fail;
+    _failExecution = fail;
+  }
+
+  function setAmountToApprove(uint256 amountToApprove) public {
+    _amountToApprove = amountToApprove;
+  }
+
+  function amountToApprove() public view returns (uint256) {
+    return _amountToApprove;
   }
 
   function executeOperation(
-    address _reserve,
+    address reserve,
-    address _destination,
+    uint256 amount,
-    uint256 _amount,
+    uint256 fee,
-    uint256 _fee,
+    bytes memory params
-    bytes memory _params
   ) public override {
     //mint to this contract the specific amount
-    MintableERC20 token = MintableERC20(_reserve);
+    MintableERC20 token = MintableERC20(reserve);
 
     //check the contract has the specified balance
-    require(
+    require(amount <= IERC20(reserve).balanceOf(address(this)), 'Invalid balance for the contract');
-      _amount <= IERC20(_reserve).balanceOf(address(this)),
-      'Invalid balance for the contract'
-    );
 
-    if (failExecution) {
+    uint256 amountToReturn = (_amountToApprove != 0) ? _amountToApprove : amount.add(fee);
-      emit ExecutedWithFail(_reserve, _amount, _fee);
+
+    if (_failExecution) {
+      emit ExecutedWithFail(reserve, amount, fee);
       return;
     }
 
     //execution does not fail - mint tokens and return them to the _destination
     //note: if the reserve is eth, the mock contract must receive at least _fee ETH before calling executeOperation
 
-    token.mint(_fee);
+    token.mint(fee);
 
-    //returning amount + fee to the destination
+    IERC20(reserve).approve(_addressesProvider.getLendingPool(), amountToReturn);
-    _transferFundsBack(_reserve, _destination, _amount.add(_fee));
 
-    emit ExecutedWithSuccess(_reserve, _amount, _fee);
+    emit ExecutedWithSuccess(reserve, amount, fee);
   }
 }

deployed-contracts.json

@@ -5,7 +5,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x58F132FBB86E21545A4Bace3C19f1C05d86d7A22",
+      "address": "0xf8c6eB390cDc5C08717bC2268aa0c1169A9B5deE",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -15,7 +15,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0xa4bcDF64Cdd5451b6ac3743B414124A6299B65FF",
+      "address": "0x4a716924Dad0c0d0E558844F304548814e7089F1",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -25,7 +25,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x5A0773Ff307Bf7C71a832dBB5312237fD3437f9F",
+      "address": "0x798c5b4b62b1eA9D64955D6751B03075A003F123",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -53,7 +53,7 @@
       "address": "0x6642B57e4265BAD868C17Fc1d1F4F88DBBA04Aa8"
     },
     "localhost": {
-      "address": "0x9EC0480CF106d6dc1c7849BA141a56F874170F97"
+      "address": "0x193101EA4C68eb894aeb922D4aC9C612a464c735"
     }
   },
   "LendingPoolDataProvider": {
@@ -66,7 +66,7 @@
       "address": "0xD9273d497eDBC967F39d419461CfcF382a0A822e"
     },
     "localhost": {
-      "address": "0x6642B57e4265BAD868C17Fc1d1F4F88DBBA04Aa8"
+      "address": "0xf9cD0476CFC1E983e9feA9366A2C08e10eFc9e25"
     }
   },
   "PriceOracle": {
@@ -75,7 +75,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x099d9fF8F818290C8b5B7Db5bFca84CEebd2714c",
+      "address": "0x18C3df59BEb7babb81BC20f61c5C175D0Cb7603d",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -85,7 +85,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0xAF6BA11790D1942625C0c2dA07da19AB63845cfF",
+      "address": "0x39ed2aE701B56AD229A19E628Bf5A515795F0AA3",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -95,7 +95,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0xD83D2773a7873ae2b5f8Fb92097e20a8C64F691E",
+      "address": "0x9434029990cF00118c28a06E014F0d7d879f28CE",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -105,7 +105,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0xf91aC1098F3b154671Ce83290114aaE45ac0225f",
+      "address": "0xccd7A2534fd4FD5119De8E368615b226e23F8F37",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -115,7 +115,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x830bceA96E56DBC1F8578f75fBaC0AF16B32A07d",
+      "address": "0x4c010BA8A40e5c13Acc1E32c025c2b2aea405Dbb",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -169,7 +169,7 @@
       "address": "0x2B681757d757fbB80cc51c6094cEF5eE75bF55aA"
     },
     "localhost": {
-      "address": "0x3bDA11B584dDff7F66E0cFe1da1562c92B45db60"
+      "address": "0x2aE520a05B31f170a18C425a1e8626aB7Ef71984"
     }
   },
   "WalletBalanceProvider": {
@@ -178,7 +178,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x392E5355a0e88Bd394F717227c752670fb3a8020",
+      "address": "0xBD2244f43f7BA73eB35A64302A6D8DBf17BdF2F1",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -188,7 +188,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x7c2C195CD6D34B8F845992d380aADB2730bB9C6F",
+      "address": "0x11df1AF606b85226Ab9a8B1FDa90395298e7494F",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -198,7 +198,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x8858eeB3DfffA017D4BCE9801D340D36Cf895CCf",
+      "address": "0x8f9A92c125FFEb83d8eC808Cd9f8cb80084c1E37",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -208,7 +208,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x0078371BDeDE8aAc7DeBfFf451B74c5EDB385Af7",
+      "address": "0xc4007844AE6bBe168cE8D692C86a7A4414FBcD26",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -218,7 +218,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0xf4e77E5Da47AC3125140c470c71cBca77B5c638c",
+      "address": "0xAb768C858C33DfcB6651d1174AFb750433a87Be0",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -228,7 +228,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x3619DbE27d7c1e7E91aA738697Ae7Bc5FC3eACA5",
+      "address": "0xA089557D64DAE4b4FcB65aB7C8A520AABb213e37",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -238,7 +238,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x038B86d9d8FAFdd0a02ebd1A476432877b0107C8",
+      "address": "0x20FAE2042b362E3FaB2806820b9A43CC116e2846",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -248,7 +248,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x1A1FEe7EeD918BD762173e4dc5EfDB8a78C924A8",
+      "address": "0x8880F314112f15C2AfF674c3B27f9a44Ca86e4d0",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -258,7 +258,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x500D1d6A4c7D8Ae28240b47c8FCde034D827fD5e",
+      "address": "0xDcb10C2e15110Db4B02C0a1df459768E680ce245",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -268,7 +268,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0xc4905364b78a742ccce7B890A89514061E47068D",
+      "address": "0xfD408ec64Da574b1859814F810564f73ea2Ff003",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -278,7 +278,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0xD6C850aeBFDC46D7F4c207e445cC0d6B0919BDBe",
+      "address": "0x0006F7c3542BEE76Dd887f54eD22405Ac4ae905a",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -288,7 +288,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x8B5B7a6055E54a36fF574bbE40cf2eA68d5554b3",
+      "address": "0x6ca94a51c644eca3F9CA315bcC41CbA6940A66Eb",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -298,7 +298,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0xEcc0a6dbC0bb4D51E4F84A315a9e5B0438cAD4f0",
+      "address": "0x6765291Cab755B980F377445eFd0F9F945CDA6C4",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -308,7 +308,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x20Ce94F404343aD2752A2D01b43fa407db9E0D00",
+      "address": "0xa7dB4d25Fc525d19Fbda4E74AAF447B88420FbcB",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -318,7 +318,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x1d80315fac6aBd3EfeEbE97dEc44461ba7556160",
+      "address": "0x273D60904A8DBa3Ae6B20505c59902644124fF0E",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -328,7 +328,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x2D8553F9ddA85A9B3259F6Bf26911364B85556F5",
+      "address": "0xfc37dE87C1Ee39cc856782BF96fEdcB6FA5c5A7f",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -338,7 +338,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x52d3b94181f8654db2530b0fEe1B19173f519C52",
+      "address": "0x049228dFFEdf91ff224e9F96247aEBA700e3590c",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -348,7 +348,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0xd15468525c35BDBC1eD8F2e09A00F8a173437f2f",
+      "address": "0xA410D1f3fEAF300842142Cd7AA1709D84944DCb7",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -358,7 +358,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x7e35Eaf7e8FBd7887ad538D4A38Df5BbD073814a",
+      "address": "0x835973768750b3ED2D5c3EF5AdcD5eDb44d12aD4",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -368,7 +368,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x5bcb88A0d20426e451332eE6C4324b0e663c50E0",
+      "address": "0x1181FC27dbF04B5105243E60BB1936c002e9d5C8",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -378,7 +378,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x3521eF8AaB0323004A6dD8b03CE890F4Ea3A13f5",
+      "address": "0x6F96975e2a0e1380b6e2e406BB33Ae96e4b6DB65",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -388,7 +388,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x53369fd4680FfE3DfF39Fc6DDa9CfbfD43daeA2E",
+      "address": "0xc032930653da193EDE295B4DcE3DD093a695c3b3",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -398,7 +398,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0xB00cC45B4a7d3e1FEE684cFc4417998A1c183e6d",
+      "address": "0xb3363f4349b1160DbA55ec4D82fDe874A4123A2a",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -408,7 +408,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x58F132FBB86E21545A4Bace3C19f1C05d86d7A22",
+      "address": "0xf8c6eB390cDc5C08717bC2268aa0c1169A9B5deE",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -417,7 +417,7 @@
       "address": "0xDf73fC454FA018051D4a1509e63D11530A59DE10"
     },
     "localhost": {
-      "address": "0x3b050AFb4ac4ACE646b31fF3639C1CD43aC31460"
+      "address": "0x18c3e48a45839B3BbC998c70A2fD41fB8D93a35D"
     }
   },
   "StableDebtToken": {
@@ -426,7 +426,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0xA0AB1cB92A4AF81f84dCd258155B5c25D247b54E",
+      "address": "0x2ca7Aa6CcCdb5D77F1c1d3E6a21fF0F7ac24C825",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -436,13 +436,13 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x5f7134cd38C826a7649f9Cc47dda24d834DD2967",
+      "address": "0x527a346011Cd6c71973f653426Ce609fa53dd59E",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
   "AToken": {
     "localhost": {
-      "address": "0xE91bBe8ee03560E3dda2786f95335F5399813Ca0",
+      "address": "0x3035D5D127487Ee5Df5FD951D9624a8b877A8497",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "buidlerevm": {
@@ -456,7 +456,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x7f23223A2FAf869962B38f5eC4aAB7f37454A45e",
+      "address": "0xAA6DfC2A802857Fadb75726B6166484e2c011cf5",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -466,7 +466,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0xf784709d2317D872237C4bC22f867d1BAe2913AB",
+      "address": "0x2cc20bE530F92865c2ed8CeD0b020a11bFe62Fe7",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -476,7 +476,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x1203D1b97BF6E546c00C45Cda035D3010ACe1180",
+      "address": "0xFd23fD3d937ae73a7b545B8Bfeb218395bDe9b8f",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
@@ -486,7 +486,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
-      "address": "0x8733AfE8174BA7c04c6CD694bD673294079b7E10",
+      "address": "0xEe821582b591CE5e4a9B7fFc4E2DAD47D3759C08",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   }

helpers/types.ts

@@ -99,6 +99,7 @@ export enum ProtocolErrors {
   SPECIFIED_CURRENCY_NOT_BORROWED_BY_USER = '40', // 'User did not borrow the specified currency'
   NOT_ENOUGH_LIQUIDITY_TO_LIQUIDATE = '41', // "There isn't enough liquidity available to liquidate"
   NO_ERRORS = '42', // 'No errors'
+  INVALID_FLASHLOAN_MODE = '43', //Invalid flashloan mode
 
   // old
 
@@ -109,6 +110,7 @@ export enum ProtocolErrors {
   INVALID_REDIRECTED_BALANCE_AFTER_TRANSFER = 'Invalid redirected balance after transfer',
   INVALID_REDIRECTION_ADDRESS = 'Invalid redirection address',
   INVALID_HF = 'Invalid health factor',
+  TRANSFER_AMOUNT_EXCEEDS_BALANCE = 'ERC20: transfer amount exceeds balance'
 }
 
 export type tEthereumAddress = string;

package.json

@@ -13,6 +13,7 @@
     "types-gen": "typechain --target ethers-v5 --outDir ./types './artifacts/*.json'",
     "test": "buidler test",
     "test-scenarios": "buidler test test/__setup.spec.ts test/scenario.spec.ts",
+    "test-flash": "buidler test test/__setup.spec.ts test/flashloan.spec.ts",
     "dev:coverage": "buidler coverage",
     "dev:deployment": "buidler dev-deployment",
     "dev:deployExample": "buidler deploy-Example",

test/flashloan.spec.ts

@@ -1,19 +1,26 @@
 import {TestEnv, makeSuite} from './helpers/make-suite';
 import {APPROVAL_AMOUNT_LENDING_POOL, oneRay} from '../helpers/constants';
-import {convertToCurrencyDecimals, getMockFlashLoanReceiver} from '../helpers/contracts-helpers';
+import {
+  convertToCurrencyDecimals,
+  getMockFlashLoanReceiver,
+  getContract,
+} from '../helpers/contracts-helpers';
 import {ethers} from 'ethers';
 import {MockFlashLoanReceiver} from '../types/MockFlashLoanReceiver';
-import {ProtocolErrors} from '../helpers/types';
+import {ProtocolErrors, eContractid} from '../helpers/types';
 import BigNumber from 'bignumber.js';
+import {VariableDebtToken} from '../types/VariableDebtToken';
+import {StableDebtToken} from '../types/StableDebtToken';
 
 const {expect} = require('chai');
 
 makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
   let _mockFlashLoanReceiver = {} as MockFlashLoanReceiver;
   const {
-    INCONSISTENT_PROTOCOL_ACTUAL_BALANCE,
+    COLLATERAL_BALANCE_IS_0,
     REQUESTED_AMOUNT_TOO_SMALL,
-    NOT_ENOUGH_LIQUIDITY_TO_BORROW,
+    TRANSFER_AMOUNT_EXCEEDS_BALANCE,
+    INVALID_FLASHLOAN_MODE
   } = ProtocolErrors;
 
   before(async () => {
@@ -31,14 +38,16 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
     await pool.deposit(weth.address, amountToDeposit, '0');
   });
 
-  it('Takes ETH flashloan, returns the funds correctly', async () => {
+  it('Takes WETH flashloan with mode = 0, returns the funds correctly', async () => {
     const {pool, deployer, weth} = testEnv;
 
     await pool.flashLoan(
       _mockFlashLoanReceiver.address,
       weth.address,
       ethers.utils.parseEther('0.8'),
-      '0x10'
+      0,
+      '0x10',
+      '0'
     );
 
     ethers.utils.parseUnits('10000');
@@ -57,18 +66,17 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
     expect(currentLiquidityIndex.toString()).to.be.equal('1000720000000000000000000000');
   });
 
-  it('Takes an ETH flashloan as big as the available liquidity', async () => {
+  it('Takes an ETH flashloan with mode = 0 as big as the available liquidity', async () => {
     const {pool, weth} = testEnv;
 
     const reserveDataBefore = await pool.getReserveData(weth.address);
-
-    console.log('Total liquidity is ', reserveDataBefore.availableLiquidity.toString());
-
     const txResult = await pool.flashLoan(
       _mockFlashLoanReceiver.address,
       weth.address,
       '1000720000000000000',
-      '0x10'
+      0,
+      '0x10',
+      '0'
     );
 
     const reserveData = await pool.getReserveData(weth.address);
@@ -85,21 +93,79 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
     expect(currentLiquidityIndex.toString()).to.be.equal('1001620648000000000000000000');
   });
 
-  it('Takes WETH flashloan, does not return the funds (revert expected)', async () => {
+  it('Takes WETH flashloan, does not return the funds with mode = 0. (revert expected)', async () => {
-    const {pool, deployer, weth} = testEnv;
+    const {pool, weth, users} = testEnv;
-
+    const caller = users[1];
-    // move funds to the MockFlashLoanReceiver contract to pay the fee
-
     await _mockFlashLoanReceiver.setFailExecutionTransfer(true);
 
     await expect(
-      pool.flashLoan(
+      pool
+        .connect(caller.signer)
+        .flashLoan(
+          _mockFlashLoanReceiver.address,
+          weth.address,
+          ethers.utils.parseEther('0.8'),
+          0,
+          '0x10',
+          '0'
+        )
+    ).to.be.revertedWith(TRANSFER_AMOUNT_EXCEEDS_BALANCE);
+  });
+
+  it('Takes a WETH flashloan with an invalid mode. (revert expected)', async () => {
+    const {pool, weth, users} = testEnv;
+    const caller = users[1];
+    await _mockFlashLoanReceiver.setFailExecutionTransfer(true);
+
+    await expect(
+      pool
+        .connect(caller.signer)
+        .flashLoan(
+          _mockFlashLoanReceiver.address,
+          weth.address,
+          ethers.utils.parseEther('0.8'),
+          4,
+          '0x10',
+          '0'
+        )
+    ).to.be.revertedWith(INVALID_FLASHLOAN_MODE);
+  });
+
+  it('Caller deposits 1000 DAI as collateral, Takes WETH flashloan with mode = 2, does not return the funds. A variable loan for caller is created', async () => {
+    const {dai, pool, weth, users} = testEnv;
+
+    const caller = users[1];
+
+    await dai.connect(caller.signer).mint(await convertToCurrencyDecimals(dai.address, '1000'));
+
+    await dai.connect(caller.signer).approve(pool.address, APPROVAL_AMOUNT_LENDING_POOL);
+
+    const amountToDeposit = await convertToCurrencyDecimals(dai.address, '1000');
+
+    await pool.connect(caller.signer).deposit(dai.address, amountToDeposit, '0');
+
+    await _mockFlashLoanReceiver.setFailExecutionTransfer(true);
+
+    await pool
+      .connect(caller.signer)
+      .flashLoan(
         _mockFlashLoanReceiver.address,
         weth.address,
         ethers.utils.parseEther('0.8'),
-        '0x10'
+        2,
-      )
+        '0x10',
-    ).to.be.revertedWith(INCONSISTENT_PROTOCOL_ACTUAL_BALANCE);
+        '0'
+      );
+    const {variableDebtTokenAddress} = await pool.getReserveTokensAddresses(weth.address);
+
+    const wethDebtToken = await getContract<VariableDebtToken>(
+      eContractid.VariableDebtToken,
+      variableDebtTokenAddress
+    );
+
+    const callerDebt = await wethDebtToken.balanceOf(caller.address);
+
+    expect(callerDebt.toString()).to.be.equal('800720000000000000', 'Invalid user debt');
   });
 
   it('tries to take a very small flashloan, which would result in 0 fees (revert expected)', async () => {
@@ -110,7 +176,9 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
         _mockFlashLoanReceiver.address,
         weth.address,
         '1', //1 wei loan
-        '0x10'
+        2,
+        '0x10',
+        '0'
       )
     ).to.be.revertedWith(REQUESTED_AMOUNT_TOO_SMALL);
   });
@@ -123,45 +191,52 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
         _mockFlashLoanReceiver.address,
         weth.address,
         '1004415000000000000', //slightly higher than the available liquidity
-        '0x10'
+        2,
+        '0x10',
+        '0'
       ),
-      NOT_ENOUGH_LIQUIDITY_TO_BORROW
+      TRANSFER_AMOUNT_EXCEEDS_BALANCE
-    ).to.be.revertedWith(NOT_ENOUGH_LIQUIDITY_TO_BORROW);
+    ).to.be.revertedWith(TRANSFER_AMOUNT_EXCEEDS_BALANCE);
   });
 
   it('tries to take a flashloan using a non contract address as receiver (revert expected)', async () => {
     const {pool, deployer, weth} = testEnv;
 
-    await expect(pool.flashLoan(deployer.address, weth.address, '1000000000000000000', '0x10')).to
+    await expect(
-      .be.reverted;
+      pool.flashLoan(deployer.address, weth.address, '1000000000000000000', 2, '0x10', '0')
+    ).to.be.reverted;
   });
 
-  it('Deposits DAI into the reserve', async () => {
+  it('Deposits USDC into the reserve', async () => {
-    const {dai, pool} = testEnv;
+    const {usdc, pool} = testEnv;
 
-    await dai.mint(await convertToCurrencyDecimals(dai.address, '1000'));
+    await usdc.mint(await convertToCurrencyDecimals(usdc.address, '1000'));
 
-    await dai.approve(pool.address, APPROVAL_AMOUNT_LENDING_POOL);
+    await usdc.approve(pool.address, APPROVAL_AMOUNT_LENDING_POOL);
 
-    const amountToDeposit = await convertToCurrencyDecimals(dai.address, '1000');
+    const amountToDeposit = await convertToCurrencyDecimals(usdc.address, '1000');
 
-    await pool.deposit(dai.address, amountToDeposit, '0');
+    await pool.deposit(usdc.address, amountToDeposit, '0');
   });
 
-  it('Takes out a 500 DAI flashloan, returns the funds correctly', async () => {
+  it('Takes out a 500 USDC flashloan, returns the funds correctly', async () => {
-    const {dai, pool, deployer: depositor} = testEnv;
+    const {usdc, pool, deployer: depositor} = testEnv;
 
     await _mockFlashLoanReceiver.setFailExecutionTransfer(false);
 
+    const flashloanAmount = await convertToCurrencyDecimals(usdc.address, '500');
+
     await pool.flashLoan(
       _mockFlashLoanReceiver.address,
-      dai.address,
+      usdc.address,
-      ethers.utils.parseEther('500'),
+      flashloanAmount,
-      '0x10'
+      0,
+      '0x10',
+      '0'
     );
 
-    const reserveData = await pool.getReserveData(dai.address);
+    const reserveData = await pool.getReserveData(usdc.address);
-    const userData = await pool.getUserReserveData(dai.address, depositor.address);
+    const userData = await pool.getUserReserveData(usdc.address, depositor.address);
 
     const totalLiquidity = reserveData.availableLiquidity
       .add(reserveData.totalBorrowsStable)
@@ -171,7 +246,7 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
     const currentLiquidityIndex = reserveData.liquidityIndex.toString();
     const currentUserBalance = userData.currentATokenBalance.toString();
 
-    const expectedLiquidity = ethers.utils.parseEther('1000.450');
+    const expectedLiquidity = await convertToCurrencyDecimals(usdc.address, '1000.450');
 
     expect(totalLiquidity).to.be.equal(expectedLiquidity, 'Invalid total liquidity');
     expect(currentLiqudityRate).to.be.equal('0', 'Invalid liquidity rate');
@@ -182,19 +257,101 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
     expect(currentUserBalance.toString()).to.be.equal(expectedLiquidity, 'Invalid user balance');
   });
 
-  it('Takes out a 500 DAI flashloan, does not return the funds (revert expected)', async () => {
+  it('Takes out a 500 USDC flashloan with mode = 0, does not return the funds. (revert expected)', async () => {
-    const {dai, pool} = testEnv;
+    const {usdc, pool, users} = testEnv;
+    const caller = users[2];
+
+    const flashloanAmount = await convertToCurrencyDecimals(usdc.address, '500');
 
     await _mockFlashLoanReceiver.setFailExecutionTransfer(true);
 
     await expect(
-      pool.flashLoan(
+      pool
-        _mockFlashLoanReceiver.address,
+        .connect(caller.signer)
-        dai.address,
+        .flashLoan(_mockFlashLoanReceiver.address, usdc.address, flashloanAmount, 2, '0x10', '0')
-        ethers.utils.parseEther('500'),
+    ).to.be.revertedWith(COLLATERAL_BALANCE_IS_0);
-        '0x10'
+  });
-      ),
+
-      INCONSISTENT_PROTOCOL_ACTUAL_BALANCE
+  it('Caller deposits 5 WETH as collateral, Takes a USDC flashloan with mode = 2, does not return the funds. A loan for caller is created', async () => {
-    ).to.be.revertedWith(INCONSISTENT_PROTOCOL_ACTUAL_BALANCE);
+    const {usdc, pool, weth, users} = testEnv;
+
+    const caller = users[2];
+
+    await weth.connect(caller.signer).mint(await convertToCurrencyDecimals(weth.address, '5'));
+
+    await weth.connect(caller.signer).approve(pool.address, APPROVAL_AMOUNT_LENDING_POOL);
+
+    const amountToDeposit = await convertToCurrencyDecimals(weth.address, '5');
+
+    await pool.connect(caller.signer).deposit(weth.address, amountToDeposit, '0');
+
+    await _mockFlashLoanReceiver.setFailExecutionTransfer(true);
+
+    const flashloanAmount = await convertToCurrencyDecimals(usdc.address, '500');
+
+    await pool
+      .connect(caller.signer)
+      .flashLoan(_mockFlashLoanReceiver.address, usdc.address, flashloanAmount, 2, '0x10', '0');
+    const {variableDebtTokenAddress} = await pool.getReserveTokensAddresses(usdc.address);
+
+    const usdcDebtToken = await getContract<VariableDebtToken>(
+      eContractid.VariableDebtToken,
+      variableDebtTokenAddress
+    );
+
+    const callerDebt = await usdcDebtToken.balanceOf(caller.address);
+
+    expect(callerDebt.toString()).to.be.equal('500450000', 'Invalid user debt');
+  });
+
+  it('Caller deposits 1000 DAI as collateral, Takes a WETH flashloan with mode = 0, does not approve the transfer of the funds', async () => {
+    const {dai, pool, weth, users} = testEnv;
+
+    const caller = users[3];
+
+    await dai.connect(caller.signer).mint(await convertToCurrencyDecimals(dai.address, '1000'));
+
+    await dai.connect(caller.signer).approve(pool.address, APPROVAL_AMOUNT_LENDING_POOL);
+
+    const amountToDeposit = await convertToCurrencyDecimals(dai.address, '1000');
+
+    await pool.connect(caller.signer).deposit(dai.address, amountToDeposit, '0');
+
+    const flashAmount = ethers.utils.parseEther('0.8');
+
+    await _mockFlashLoanReceiver.setFailExecutionTransfer(false);
+    await _mockFlashLoanReceiver.setAmountToApprove(flashAmount.div(2));
+
+    await expect(
+      pool
+        .connect(caller.signer)
+        .flashLoan(_mockFlashLoanReceiver.address, weth.address, flashAmount, 0, '0x10', '0')
+    ).to.be.revertedWith('ERC20: transfer amount exceeds allowance');
+  });
+
+  it('Caller takes a WETH flashloan with mode = 1', async () => {
+    const {dai, pool, weth, users} = testEnv;
+
+    const caller = users[3];
+
+    const flashAmount = ethers.utils.parseEther('0.8');
+
+    await _mockFlashLoanReceiver.setFailExecutionTransfer(true);
+
+    await pool
+        .connect(caller.signer)
+        .flashLoan(_mockFlashLoanReceiver.address, weth.address, flashAmount, 1, '0x10', '0');
+
+    const {stableDebtTokenAddress} = await pool.getReserveTokensAddresses(weth.address);
+
+    const wethDebtToken = await getContract<StableDebtToken>(
+      eContractid.VariableDebtToken,
+      stableDebtTokenAddress
+    );
+
+    const callerDebt = await wethDebtToken.balanceOf(caller.address);
+
+    expect(callerDebt.toString()).to.be.equal('800720000000000000', 'Invalid user debt');
+  
   });
 });