From df885a928190bf450a916bfd694b4cf89f8f3f4f Mon Sep 17 00:00:00 2001
From: Adam Cuculich <46691282+cucupac@users.noreply.github.com>
Date: Tue, 16 Jan 2024 16:24:56 -0600
Subject: [PATCH] refactor: add repay buffer (#6)

---
 src/services/DebtService.sol    |  5 +++--
 test/PositionAdmin.t.sol        |  5 +----
 test/PositionFactory.t.sol      |  5 +----
 test/common/Constants.t.sol     |  1 +
 test/services/DebtService.t.sol | 13 +++++++++++--
 5 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/src/services/DebtService.sol b/src/services/DebtService.sol
index 806ef0d2..c6102d0c 100644
--- a/src/services/DebtService.sol
+++ b/src/services/DebtService.sol
@@ -102,11 +102,12 @@ contract DebtService is PositionAdmin {
 
     /**
      * @notice Returns this contract's total debt (principle + interest).
-     * @return outstandingDebt This contract's total debt (units: D_DECIMALS).
+     * @return outstandingDebt This contract's total debt + small buffer (units: D_DECIMALS).
      */
     function _getDebtAmt() internal view returns (uint256) {
         address variableDebtTokenAddress = IPool(AAVE_POOL).getReserveData(D_TOKEN).variableDebtTokenAddress;
-        return IERC20(variableDebtTokenAddress).balanceOf(address(this));
+        /// @dev adds repay buffer of 2 units to ensure a full repay (units: D_DECIMALS)
+        return IERC20(variableDebtTokenAddress).balanceOf(address(this)) + 2;
     }
 
     /**
diff --git a/test/PositionAdmin.t.sol b/test/PositionAdmin.t.sol
index 86979cd1..465e07c8 100644
--- a/test/PositionAdmin.t.sol
+++ b/test/PositionAdmin.t.sol
@@ -153,12 +153,11 @@ contract PositionAdminTest is Test, TokenUtils {
     // - The contract's native balance should increase by the amount transferred.
     function testFuzz_Receive(uint256 _amount, address _sender) public {
         // Assumptions
-        vm.assume(_amount != 0 && _amount <= 1000 ether);
+        _amount = bound(_amount, 1, 1_000 ether);
         uint256 gasMoney = 1 ether;
         vm.deal(_sender, _amount + gasMoney);
 
         // Pre-Act Data
-        uint256 preSenderBalance = _sender.balance;
         uint256 preContractBalance = positionAddr.balance;
 
         // Act
@@ -166,12 +165,10 @@ contract PositionAdminTest is Test, TokenUtils {
         (bool success,) = payable(positionAddr).call{ value: _amount }("");
 
         // Post-Act Data
-        uint256 postSenderBalance = _sender.balance;
         uint256 postContractBalance = positionAddr.balance;
 
         // Assertions
         assertTrue(success);
-        assertEq(postSenderBalance, preSenderBalance - _amount);
         assertEq(postContractBalance, preContractBalance + _amount);
     }
 
diff --git a/test/PositionFactory.t.sol b/test/PositionFactory.t.sol
index 92f9390f..762392f3 100644
--- a/test/PositionFactory.t.sol
+++ b/test/PositionFactory.t.sol
@@ -274,12 +274,11 @@ contract PositionFactoryTest is Test, TokenUtils {
     // - The contract's native balance should increase by the amount transferred.
     function testFuzz_Receive(uint256 _amount, address _sender) public {
         // Assumptions
-        vm.assume(_amount != 0 && _amount <= 1000 ether);
+        _amount = bound(_amount, 1, 1_000 ether);
         uint256 gasMoney = 1 ether;
         vm.deal(_sender, _amount + gasMoney);
 
         // Pre-Act Data
-        uint256 preSenderBalance = _sender.balance;
         uint256 preContractBalance = address(positionFactory).balance;
 
         // Act
@@ -287,12 +286,10 @@ contract PositionFactoryTest is Test, TokenUtils {
         (bool success,) = payable(address(positionFactory)).call{ value: _amount }("");
 
         // Post-Act Data
-        uint256 postSenderBalance = _sender.balance;
         uint256 postContractBalance = address(positionFactory).balance;
 
         // Assertions
         assertTrue(success);
-        assertEq(postSenderBalance, preSenderBalance - _amount);
         assertEq(postContractBalance, preContractBalance + _amount);
     }
 
diff --git a/test/common/Constants.t.sol b/test/common/Constants.t.sol
index d913262c..883a6bba 100644
--- a/test/common/Constants.t.sol
+++ b/test/common/Constants.t.sol
@@ -19,6 +19,7 @@ address constant USDC_HOLDER = 0x47c031236e19d024b42f8AE6780E44A573170703;
 uint256 constant PROFIT_PERCENT = 25;
 uint256 constant REPAY_PERCENT = 75;
 uint256 constant WITHDRAW_BUFFER = 100_000;
+uint256 constant REPAY_BUFFER = 2;
 
 contract Assets {
     address[4] public supported = [USDC, DAI, WETH, WBTC];
diff --git a/test/services/DebtService.t.sol b/test/services/DebtService.t.sol
index 03108a88..81af5f66 100644
--- a/test/services/DebtService.t.sol
+++ b/test/services/DebtService.t.sol
@@ -9,7 +9,16 @@ import { PositionAdmin } from "src/PositionAdmin.sol";
 import { DebtServiceHarness } from "test/harness/DebtServiceHarness.t.sol";
 import { DebtUtils } from "test/services/utils/DebtUtils.t.sol";
 import { TokenUtils } from "test/common/utils/TokenUtils.t.sol";
-import { Assets, AAVE_ORACLE, AAVE_POOL, DAI, USDC, USDC_HOLDER, WITHDRAW_BUFFER } from "test/common/Constants.t.sol";
+import {
+    Assets,
+    AAVE_ORACLE,
+    AAVE_POOL,
+    DAI,
+    REPAY_BUFFER,
+    USDC,
+    USDC_HOLDER,
+    WITHDRAW_BUFFER
+} from "test/common/Constants.t.sol";
 import { IAaveOracle } from "src/interfaces/aave/IAaveOracle.sol";
 import { IPool } from "src/interfaces/aave/IPool.sol";
 import { IERC20 } from "src/interfaces/token/IERC20.sol";
@@ -295,7 +304,7 @@ contract DebtServiceTest is Test, DebtUtils, TokenUtils {
             uint256 debtAmt = debtServices[i].exposed_getDebtAmt();
 
             // Assertions
-            assertApproxEqAbs(debtAmt, dAmt, 1);
+            assertApproxEqAbs(debtAmt, dAmt + REPAY_BUFFER, 1);
         }
     }