Refactoring of credit delegation

contracts/interfaces/ILendingPool.sol

@@ -33,13 +33,6 @@ interface ILendingPool {
    **/
   event Withdraw(address indexed reserve, address indexed user, address indexed to, uint256 amount);
 
-  event BorrowAllowanceDelegated(
-    address indexed fromUser,
-    address indexed toUser,
-    address[] assets,
-    uint256[] interestRateModes,
-    uint256[] amounts
-  );
   /**
    * @dev emitted on borrow
    * @param reserve the address of the reserve
@@ -196,27 +189,6 @@ interface ILendingPool {
     address to
   ) external;
 
-  /**
-   * @dev Sets allowance to borrow on a certain type of debt assets for a certain user address
-   * @param assets The underlying asset of each debt token
-   * @param user The user to give allowance to
-   * @param interestRateModes Types of debt: 1 for stable, 2 for variable
-   * @param amounts Allowance amounts to borrow
-   **/
-  function delegateBorrowAllowance(
-    address[] calldata assets,
-    address user,
-    uint256[] calldata interestRateModes,
-    uint256[] calldata amounts
-  ) external;
-
-  function getBorrowAllowance(
-    address fromUser,
-    address toUser,
-    address asset,
-    uint256 interestRateMode
-  ) external view returns (uint256);
-
   /**
    * @dev Allows users to borrow a specific amount of the reserve currency, provided that the borrower
    * already deposited enough collateral.

contracts/lendingpool/LendingPool.sol

@@ -166,53 +166,6 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
     emit Withdraw(asset, msg.sender, to, amountToWithdraw);
   }
 
-  /**
-   * @dev returns the borrow allowance of the user
-   * @param asset The underlying asset of the debt token
-   * @param fromUser The user to giving allowance
-   * @param toUser The user to give allowance to
-   * @param interestRateMode Type of debt: 1 for stable, 2 for variable
-   * @return the current allowance of toUser
-   **/
-  function getBorrowAllowance(
-    address fromUser,
-    address toUser,
-    address asset,
-    uint256 interestRateMode
-  ) external override view returns (uint256) {
-    return
-      _borrowAllowance[_reserves[asset].getDebtTokenAddress(interestRateMode)][fromUser][toUser];
-  }
-
-  /**
-   * @dev Sets allowance to borrow on a certain type of debt assets for a certain user address
-   * @param assets The underlying asset of each debt token
-   * @param user The user to give allowance to
-   * @param interestRateModes Types of debt: 1 for stable, 2 for variable
-   * @param amounts Allowance amounts to borrow
-   **/
-  function delegateBorrowAllowance(
-    address[] calldata assets,
-    address user,
-    uint256[] calldata interestRateModes,
-    uint256[] calldata amounts
-  ) external override {
-    _whenNotPaused();
-
-    uint256 countAssets = assets.length;
-    require(
-      countAssets == interestRateModes.length && countAssets == amounts.length,
-      Errors.LP_INCONSISTENT_PARAMS_LENGTH
-    );
-
-    for (uint256 i = 0; i < countAssets; i++) {
-      address debtToken = _reserves[assets[i]].getDebtTokenAddress(interestRateModes[i]);
-      _borrowAllowance[debtToken][msg.sender][user] = amounts[i];
-    }
-
-    emit BorrowAllowanceDelegated(msg.sender, user, assets, interestRateModes, amounts);
-  }
-
   /**
    * @dev Allows users to borrow a specific amount of the reserve currency, provided that the borrower
    * already deposited enough collateral.
@@ -338,6 +291,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
       //burn stable rate tokens, mint variable rate tokens
       IStableDebtToken(reserve.stableDebtTokenAddress).burn(msg.sender, stableDebt);
       IVariableDebtToken(reserve.variableDebtTokenAddress).mint(
+        msg.sender,
         msg.sender,
         stableDebt,
         reserve.variableBorrowIndex
@@ -350,6 +304,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
         reserve.variableBorrowIndex
       );
       IStableDebtToken(reserve.stableDebtTokenAddress).mint(
+        msg.sender,
         msg.sender,
         variableDebt,
         reserve.currentStableBorrowRate
@@ -411,6 +366,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
 
     IStableDebtToken(address(stableDebtToken)).burn(user, stableBorrowBalance);
     IStableDebtToken(address(stableDebtToken)).mint(
+      user,
       user,
       stableBorrowBalance,
       reserve.currentStableBorrowRate
@@ -898,14 +854,6 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
       oracle
     );
 
-    if (vars.onBehalfOf != msg.sender) {
-      address debtToken = reserve.getDebtTokenAddress(vars.interestRateMode);
-
-      _borrowAllowance[debtToken][vars.onBehalfOf][msg.sender] = _borrowAllowance[debtToken][vars
-        .onBehalfOf][msg.sender]
-        .sub(vars.amount, Errors.LP_BORROW_ALLOWANCE_NOT_ENOUGH);
-    }
-
     reserve.updateState();
 
     //caching the current stable borrow rate
@@ -918,12 +866,14 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
       currentStableRate = reserve.currentStableBorrowRate;
 
       isFirstBorrowing = IStableDebtToken(reserve.stableDebtTokenAddress).mint(
+        vars.user,
         vars.onBehalfOf,
         vars.amount,
         currentStableRate
       );
     } else {
       isFirstBorrowing = IVariableDebtToken(reserve.variableDebtTokenAddress).mint(
+        vars.user,
         vars.onBehalfOf,
         vars.amount,
         reserve.variableBorrowIndex

contracts/lendingpool/LendingPoolStorage.sol

@@ -15,8 +15,6 @@ contract LendingPoolStorage {
 
   mapping(address => ReserveLogic.ReserveData) internal _reserves;
   mapping(address => UserConfiguration.Map) internal _usersConfig;
-  // debt token address => user who gives allowance => user who receives allowance => amount
-  mapping(address => mapping(address => mapping(address => uint256))) internal _borrowAllowance;
 
   // the list of the available reserves, structured as a mapping for gas savings reasons
   mapping(uint256 => address) internal _reservesList;

contracts/libraries/helpers/Errors.sol

@@ -19,6 +19,7 @@ pragma solidity ^0.6.8;
 library Errors {
   //common errors
   string public constant CALLER_NOT_AAVE_ADMIN = '33'; // 'The caller must be the aave admin'
+  string public constant BORROW_ALLOWANCE_NOT_ENOUGH = '59'; // User borrows on behalf, but allowance are too small
 
   //contract specific errors
   string public constant VL_AMOUNT_NOT_GREATER_THAN_0 = '1'; // 'Amount must be greater than 0'
@@ -79,7 +80,6 @@ library Errors {
   string public constant AT_INVALID_MINT_AMOUNT = '56'; //invalid amount to mint
   string public constant LP_FAILED_REPAY_WITH_COLLATERAL = '57';
   string public constant AT_INVALID_BURN_AMOUNT = '58'; //invalid amount to burn
-  string public constant LP_BORROW_ALLOWANCE_NOT_ENOUGH = '59'; // User borrows on behalf, but allowance are too small
   string public constant LP_FAILED_COLLATERAL_SWAP = '60';
   string public constant LP_INVALID_EQUAL_ASSETS_TO_SWAP = '61';
   string public constant LP_REENTRANCY_NOT_ALLOWED = '62';

contracts/libraries/logic/ReserveLogic.sol

@@ -119,28 +119,6 @@ library ReserveLogic {
     return cumulated;
   }
 
-  /**
-   * @dev returns an address of the debt token used for particular interest rate mode on asset.
-   * @param reserve the reserve object
-   * @param interestRateMode - STABLE or VARIABLE from ReserveLogic.InterestRateMode enum
-   * @return an address of the corresponding debt token from reserve configuration
-   **/
-  function getDebtTokenAddress(ReserveLogic.ReserveData storage reserve, uint256 interestRateMode)
-    external
-    view
-    returns (address)
-  {
-    require(
-      ReserveLogic.InterestRateMode.STABLE == ReserveLogic.InterestRateMode(interestRateMode) ||
-        ReserveLogic.InterestRateMode.VARIABLE == ReserveLogic.InterestRateMode(interestRateMode),
-      Errors.VL_INVALID_INTEREST_RATE_MODE_SELECTED
-    );
-    return
-      ReserveLogic.InterestRateMode.STABLE == ReserveLogic.InterestRateMode(interestRateMode)
-        ? reserve.stableDebtTokenAddress
-        : reserve.variableDebtTokenAddress;
-  }
-
   /**
    * @dev Updates the liquidity cumulative index Ci and variable borrow cumulative index Bvc. Refer to the whitepaper for
    * a formal specification.

contracts/tokenization/StableDebtToken.sol

@@ -5,6 +5,7 @@ import {DebtTokenBase} from './base/DebtTokenBase.sol';
 import {MathUtils} from '../libraries/math/MathUtils.sol';
 import {WadRayMath} from '../libraries/math/WadRayMath.sol';
 import {IStableDebtToken} from './interfaces/IStableDebtToken.sol';
+import '@nomiclabs/buidler/console.sol';
 
 /**
  * @title contract StableDebtToken
@@ -16,9 +17,10 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
 
   uint256 public constant DEBT_TOKEN_REVISION = 0x1;
 
-  uint256 private _avgStableRate;
-  mapping(address => uint40) _timestamps;
-  uint40 _totalSupplyTimestamp;
+  uint256 internal _avgStableRate;
+  mapping(address => uint40) internal _timestamps;
+  mapping(address => uint256) internal _usersData;
+  uint40 internal _totalSupplyTimestamp;
 
   constructor(
     address pool,
@@ -95,17 +97,20 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
    **/
   function mint(
     address user,
+    address onBehalfOf,
     uint256 amount,
     uint256 rate
   ) external override onlyLendingPool returns (bool) {
     MintLocalVars memory vars;
 
+    if (user != onBehalfOf) {
+      _decreaseBorrowAllowance(onBehalfOf, user, amount);
+    }
+
+    console.log('Invoked mint for %s and %s', user, onBehalfOf);
+
     //cumulates the user debt
-    (
-      uint256 previousBalance,
-      uint256 currentBalance,
-      uint256 balanceIncrease
-    ) = _calculateBalanceIncrease(user);
+    (, uint256 currentBalance, uint256 balanceIncrease) = _calculateBalanceIncrease(onBehalfOf);
 
     //accrueing the interest accumulation to the stored total supply and caching it
     vars.previousSupply = totalSupply();
@@ -115,17 +120,17 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
     vars.amountInRay = amount.wadToRay();
 
     //calculates the new stable rate for the user
-    vars.newStableRate = _usersData[user]
+    vars.newStableRate = _usersData[onBehalfOf]
       .rayMul(currentBalance.wadToRay())
       .add(vars.amountInRay.rayMul(rate))
       .rayDiv(currentBalance.add(amount).wadToRay());
 
     require(vars.newStableRate < (1 << 128), 'Debt token: stable rate overflow');
-    _usersData[user] = vars.newStableRate;
+    _usersData[onBehalfOf] = vars.newStableRate;
 
     //updating the user and supply timestamp
     //solium-disable-next-line
-    _totalSupplyTimestamp = _timestamps[user] = uint40(block.timestamp);
+    _totalSupplyTimestamp = _timestamps[onBehalfOf] = uint40(block.timestamp);
 
     //calculates the updated average stable rate
     vars.currentAvgStableRate = _avgStableRate = vars
@@ -134,13 +139,14 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
       .add(rate.rayMul(vars.amountInRay))
       .rayDiv(vars.nextSupply.wadToRay());
 
-    _mint(user, amount.add(balanceIncrease), vars.previousSupply);
+    _mint(onBehalfOf, amount.add(balanceIncrease), vars.previousSupply);
 
     // transfer event to track balances
-    emit Transfer(address(0), user, amount);
+    emit Transfer(address(0), onBehalfOf, amount);
 
     emit Mint(
       user,
+      onBehalfOf,
       amount,
       currentBalance,
       balanceIncrease,
@@ -158,11 +164,7 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
    * @param amount the amount of debt tokens to mint
    **/
   function burn(address user, uint256 amount) external override onlyLendingPool {
-    (
-      uint256 previousBalance,
-      uint256 currentBalance,
-      uint256 balanceIncrease
-    ) = _calculateBalanceIncrease(user);
+    (, uint256 currentBalance, uint256 balanceIncrease) = _calculateBalanceIncrease(user);
 
     uint256 previousSupply = totalSupply();
     uint256 newStableRate = 0;

contracts/tokenization/VariableDebtToken.sol

@@ -55,17 +55,22 @@ contract VariableDebtToken is DebtTokenBase, IVariableDebtToken {
    **/
   function mint(
     address user,
+    address onBehalfOf,
     uint256 amount,
     uint256 index
   ) external override onlyLendingPool returns (bool) {
-    uint256 previousBalance = super.balanceOf(user);
+    if (user != onBehalfOf) {
+      _decreaseBorrowAllowance(onBehalfOf, user, amount);
+    }
+
+    uint256 previousBalance = super.balanceOf(onBehalfOf);
     uint256 amountScaled = amount.rayDiv(index);
     require(amountScaled != 0, Errors.AT_INVALID_MINT_AMOUNT);
 
-    _mint(user, amountScaled);
+    _mint(onBehalfOf, amountScaled);
 
-    emit Transfer(address(0), user, amount);
-    emit Mint(user, amount, index);
+    emit Transfer(address(0), onBehalfOf, amount);
+    emit Mint(user, onBehalfOf, amount, index);
 
     return previousBalance == 0;
   }

contracts/tokenization/base/DebtTokenBase.sol

@@ -15,9 +15,17 @@ import {Errors} from '../../libraries/helpers/Errors.sol';
  */
 
 abstract contract DebtTokenBase is IncentivizedERC20, VersionedInitializable {
+  event BorrowAllowanceDelegated(
+    address indexed fromUser,
+    address indexed toUser,
+    address asset,
+    uint256 amount
+  );
+
   address public immutable UNDERLYING_ASSET_ADDRESS;
   ILendingPool public immutable POOL;
-  mapping(address => uint256) internal _usersData;
+
+  mapping(address => mapping(address => uint256)) internal _borrowAllowances;
 
   /**
    * @dev Only lending pool can call functions marked by this modifier
@@ -58,6 +66,28 @@ abstract contract DebtTokenBase is IncentivizedERC20, VersionedInitializable {
     _setDecimals(decimals);
   }
 
+  /**
+   * @dev delegates borrowing power to a user on the specific debt token
+   * @param delegatee the address receiving the delegated borrowing power
+   * @param amount the maximum amount being delegated. Delegation will still
+   * respect the liquidation constraints (even if delegated, a delegatee cannot
+   * force a delegator HF to go below 1)
+   **/
+  function approveDelegation(address delegatee, uint256 amount) external {
+    _borrowAllowances[_msgSender()][delegatee] = amount;
+    emit BorrowAllowanceDelegated(_msgSender(), delegatee, UNDERLYING_ASSET_ADDRESS, amount);
+  }
+
+  /**
+   * @dev returns the borrow allowance of the user
+   * @param fromUser The user to giving allowance
+   * @param toUser The user to give allowance to
+   * @return the current allowance of toUser
+   **/
+  function borrowAllowance(address fromUser, address toUser) external view returns (uint256) {
+    return _borrowAllowances[fromUser][toUser];
+  }
+
   /**
    * @dev Being non transferrable, the debt token does not implement any of the
    * standard ERC20 functions for transfer and allowance.
@@ -118,4 +148,19 @@ abstract contract DebtTokenBase is IncentivizedERC20, VersionedInitializable {
     subtractedValue;
     revert('ALLOWANCE_NOT_SUPPORTED');
   }
+
+  function _decreaseBorrowAllowance(
+    address delegator,
+    address delegatee,
+    uint256 amount
+  ) internal {
+    uint256 newAllowance = _borrowAllowances[delegator][delegatee].sub(
+      amount,
+      Errors.BORROW_ALLOWANCE_NOT_ENOUGH
+    );
+
+    _borrowAllowances[delegator][delegatee] = newAllowance;
+
+    emit BorrowAllowanceDelegated(delegator, delegatee, UNDERLYING_ASSET_ADDRESS, newAllowance);
+  }
 }

contracts/tokenization/interfaces/IAToken.sol

@@ -5,6 +5,27 @@ import {IERC20} from '../../dependencies/openzeppelin/contracts/IERC20.sol';
 import {IScaledBalanceToken} from './IScaledBalanceToken.sol';
 
 interface IAToken is IERC20, IScaledBalanceToken {
+  /**
+   * @dev emitted after the mint action
+   * @param from the address performing the mint
+   * @param value the amount to be minted
+   * @param index the last index of the reserve
+   **/
+  event Mint(address indexed from, uint256 value, uint256 index);
+
+  /**
+   * @dev mints aTokens to user
+   * only lending pools can call this function
+   * @param user the address receiving the minted tokens
+   * @param amount the amount of tokens to mint
+   * @param index the liquidity index
+   */
+  function mint(
+    address user,
+    uint256 amount,
+    uint256 index
+  ) external returns (bool);
+
   /**
    * @dev emitted after aTokens are burned
    * @param from the address performing the redeem

contracts/tokenization/interfaces/IScaledBalanceToken.sol

@@ -2,27 +2,6 @@
 pragma solidity ^0.6.8;
 
 interface IScaledBalanceToken {
-  /**
-   * @dev emitted after the mint action
-   * @param from the address performing the mint
-   * @param value the amount to be minted
-   * @param index the last index of the reserve
-   **/
-  event Mint(address indexed from, uint256 value, uint256 index);
-
-  /**
-   * @dev mints aTokens to user
-   * only lending pools can call this function
-   * @param user the address receiving the minted tokens
-   * @param amount the amount of tokens to mint
-   * @param index the liquidity index
-   */
-  function mint(
-    address user,
-    uint256 amount,
-    uint256 index
-  ) external returns (bool);
-
   /**
    * @dev returns the principal balance of the user. The principal balance is the last
    * updated stored balance, which does not consider the perpetually accruing interest.

contracts/tokenization/interfaces/IStableDebtToken.sol

@@ -15,7 +15,8 @@ pragma solidity ^0.6.8;
 interface IStableDebtToken {
   /**
    * @dev emitted when new stable debt is minted
-   * @param user the address of the user
+   * @param user the address of the user who triggered the minting
+   * @param onBehalfOf the address of the user
    * @param amount the amount minted
    * @param currentBalance the current balance of the user
    * @param balanceIncrease the the increase in balance since the last action of the user
@@ -25,6 +26,7 @@ interface IStableDebtToken {
    **/
   event Mint(
     address indexed user,
+    address indexed onBehalfOf,
     uint256 amount,
     uint256 currentBalance,
     uint256 balanceIncrease,
@@ -60,6 +62,7 @@ interface IStableDebtToken {
    **/
   function mint(
     address user,
+    address onBehalfOf,
     uint256 amount,
     uint256 rate
   ) external returns (bool);

contracts/tokenization/interfaces/IVariableDebtToken.sol

@@ -9,6 +9,29 @@ import {IScaledBalanceToken} from './IScaledBalanceToken.sol';
  * @notice defines the basic interface for a variable debt token.
  **/
 interface IVariableDebtToken is IScaledBalanceToken {
+  /**
+   * @dev emitted after the mint action
+   * @param from the address performing the mint
+   * @param onBehalfOf the address of the user on which behalf minting has been performed
+   * @param value the amount to be minted
+   * @param index the last index of the reserve
+   **/
+  event Mint(address indexed from, address indexed onBehalfOf, uint256 value, uint256 index);
+
+  /**
+   * @dev mints aTokens to user
+   * only lending pools can call this function
+   * @param user the address receiving the minted tokens
+   * @param amount the amount of tokens to mint
+   * @param index the liquidity index
+   */
+  function mint(
+    address user,
+    address onBehalfOf,
+    uint256 amount,
+    uint256 index
+  ) external returns (bool);
+
   /**
    * @dev emitted when variable debt is burnt
    * @param user the user which debt has been burned

deployed-contracts.json

@@ -163,26 +163,25 @@
   },
   "ReserveLogic": {
     "buidlerevm": {
-      "address": "0x78Ee8Fb9fE5abD5e347Fc94c2fb85596d1f60e3c",
+      "address": "0xFAe0fd738dAbc8a0426F47437322b6d026A9FD95",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
   "GenericLogic": {
     "buidlerevm": {
-      "address": "0x920d847fE49E54C19047ba8bc236C45A8068Bca7",
+      "address": "0x6082731fdAba4761277Fb31299ebC782AD3bCf24",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
   "ValidationLogic": {
     "buidlerevm": {
-      "address": "0xA4765Ff72A9F3CfE73089bb2c3a41B838DF71574",
+      "address": "0x8456161947DFc1fC159A0B26c025cD2b4bba0c3e",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },
   "LendingPool": {
     "buidlerevm": {
-      "address": "0x35c1419Da7cf0Ff885B8Ef8EA9242FEF6800c99b",
-      "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
+      "address": "0xD9273d497eDBC967F39d419461CfcF382a0A822e"
     }
   },
   "LendingPoolConfigurator": {
@@ -198,7 +197,7 @@
   },
   "ATokensAndRatesHelper": {
     "buidlerevm": {
-      "address": "0x920d847fE49E54C19047ba8bc236C45A8068Bca7",
+      "address": "0x06bA8d8af0dF898D0712DffFb0f862cC51AF45c2",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },

test/flashloan.spec.ts

@@ -454,10 +454,12 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
 
     const flashAmount = ethers.utils.parseEther('0.8');
 
+    const reserveData = await pool.getReserveData(weth.address);
+
+    const stableDebtToken = await getVariableDebtToken(reserveData.stableDebtTokenAddress);
+
     // Deposited for onBehalfOf user already, delegate borrow allowance
-    await pool
-      .connect(onBehalfOf.signer)
-      .delegateBorrowAllowance([weth.address], caller.address, [1], [flashAmount]);
+    await stableDebtToken.connect(onBehalfOf.signer).approveDelegation(caller.address, flashAmount);
 
     await _mockFlashLoanReceiver.setFailExecutionTransfer(true);
 

test/helpers/actions.ts

@@ -18,7 +18,12 @@ import {
 import {getReserveAddressFromSymbol, getReserveData, getUserData} from './utils/helpers';
 
 import {convertToCurrencyDecimals} from '../../helpers/contracts-helpers';
-import {getAToken, getMintableErc20} from '../../helpers/contracts-getters';
+import {
+  getAToken,
+  getMintableErc20,
+  getStableDebtToken,
+  getVariableDebtToken,
+} from '../../helpers/contracts-getters';
 import {MAX_UINT_AMOUNT, ONE_YEAR} from '../../helpers/constants';
 import {SignerWithAddress, TestEnv} from './make-suite';
 import {BRE, increaseTime, timeLatest, waitForTx} from '../../helpers/misc-utils';
@@ -277,9 +282,9 @@ export const withdraw = async (
 };
 
 export const delegateBorrowAllowance = async (
-  reserveSymbols: string[],
-  amounts: string[],
-  interestRateModes: string[],
+  reserve: string,
+  amount: string,
+  interestRateMode: string,
   user: SignerWithAddress,
   receiver: tEthereumAddress,
   expectedResult: string,
@@ -288,32 +293,33 @@ export const delegateBorrowAllowance = async (
 ) => {
   const {pool} = testEnv;
 
-  const reserves: tEthereumAddress[] = [];
-  const amountsToDelegate: tEthereumAddress[] = [];
-  for (const reserveSymbol of reserveSymbols) {
-    const newLength = reserves.push(await getReserveAddressFromSymbol(reserveSymbol));
-    amountsToDelegate.push(
-      await (
-        await convertToCurrencyDecimals(reserves[newLength - 1], amounts[newLength - 1])
-      ).toString()
-    );
-  }
+  const reserveAddress: tEthereumAddress = await getReserveAddressFromSymbol(reserve);
 
-  const delegateAllowancePromise = pool
+  const amountToDelegate: string = await (
+    await convertToCurrencyDecimals(reserveAddress, amount)
+  ).toString();
+
+  const reserveData = await pool.getReserveData(reserveAddress);
+
+  const debtToken =
+    interestRateMode === 'stable'
+      ? await getStableDebtToken(reserveData.stableDebtTokenAddress)
+      : await getVariableDebtToken(reserveData.variableDebtTokenAddress);
+
+  const delegateAllowancePromise = debtToken
     .connect(user.signer)
-    .delegateBorrowAllowance(reserves, receiver, interestRateModes, amountsToDelegate);
+    .approveDelegation(receiver, amountToDelegate);
+
   if (expectedResult === 'revert') {
     await expect(delegateAllowancePromise, revertMessage).to.be.reverted;
     return;
   } else {
     await delegateAllowancePromise;
-    for (const [i, reserve] of reserves.entries()) {
-      expect(
-        (
-          await pool.getBorrowAllowance(user.address, receiver, reserve, interestRateModes[i])
-        ).toString()
-      ).to.be.equal(amountsToDelegate[i], 'borrowAllowance are set incorrectly');
-    }
+    const allowance = await debtToken.borrowAllowance(user.address, receiver);
+    expect(allowance.toString()).to.be.equal(
+      amountToDelegate,
+      'borrowAllowance are set incorrectly'
+    );
   }
 };
 

test/helpers/scenario-engine.ts

@@ -121,9 +121,9 @@ const executeAction = async (action: Action, users: SignerWithAddress[], testEnv
         }
 
         await delegateBorrowAllowance(
-          [reserve],
-          [amount],
-          [rateMode],
+          reserve,
+          amount,
+          rateMode,
           user,
           toUser,
           expected,

test/pausable-functions.spec.ts

@@ -122,23 +122,6 @@ makeSuite('Pausable Pool', (testEnv: TestEnv) => {
     await configurator.setPoolPause(false);
   });
 
-  it('DelegateBorrowAllowance', async () => {
-    const {pool, dai, users, configurator} = testEnv;
-
-    const user = users[1];
-    const toUser = users[2];
-    // Pause the pool
-    await configurator.setPoolPause(true);
-
-    // Try to execute liquidation
-    await expect(
-      pool.connect(user.signer).delegateBorrowAllowance([dai.address], toUser.address, ['1'], ['1'])
-    ).revertedWith(LP_IS_PAUSED);
-
-    // Unpause the pool
-    await configurator.setPoolPause(false);
-  });
-
   it('Borrow', async () => {
     const {pool, dai, users, configurator} = testEnv;
 

test/scenario.spec.ts

@@ -10,7 +10,7 @@ import {executeStory} from './helpers/scenario-engine';
 
 const scenarioFolder = './test/helpers/scenarios/';
 
-const selectedScenarios: string[] = [];
+const selectedScenarios: string[] = [`credit-delegation.json`];
 
 fs.readdirSync(scenarioFolder).forEach((file) => {
   if (selectedScenarios.length > 0 && !selectedScenarios.includes(file)) return;

test/stable-token.spec.ts

@@ -16,9 +16,9 @@ makeSuite('Stable debt token tests', (testEnv: TestEnv) => {
 
     const stableDebtContract = await getStableDebtToken(daiStableDebtTokenAddress);
 
-    await expect(stableDebtContract.mint(deployer.address, '1', '1')).to.be.revertedWith(
-      AT_CALLER_MUST_BE_LENDING_POOL
-    );
+    await expect(
+      stableDebtContract.mint(deployer.address, deployer.address, '1', '1')
+    ).to.be.revertedWith(AT_CALLER_MUST_BE_LENDING_POOL);
   });
 
   it('Tries to invoke burn not being the LendingPool', async () => {

test/variable-debt-token.spec.ts

@@ -15,9 +15,9 @@ makeSuite('Variable debt token tests', (testEnv: TestEnv) => {
 
     const variableDebtContract = await getVariableDebtToken(daiVariableDebtTokenAddress);
 
-    await expect(variableDebtContract.mint(deployer.address, '1', '1')).to.be.revertedWith(
-      AT_CALLER_MUST_BE_LENDING_POOL
-    );
+    await expect(
+      variableDebtContract.mint(deployer.address, deployer.address, '1', '1')
+    ).to.be.revertedWith(AT_CALLER_MUST_BE_LENDING_POOL);
   });
 
   it('Tries to invoke burn not being the LendingPool', async () => {