Resolve PR feedback

Author: Sean329

contracts/src/matching/HyperdriveMatchingEngineV2.sol

@@ -1459,6 +1459,18 @@ contract HyperdriveMatchingEngineV2 is
         uint256 governanceFee = 2 * flatFee.mulDown(config.fees.governanceLP);
         cost += governanceFee;
 
+        // @dev we can use hyperdrive.convertToBase and hyperdrive.convertToShares
+        //      to simulate the conversions made within the yield source. When we
+        //      are using base, what happens under the hood is that the calculations
+        //      will flow as:
+        //      1. Deposit base into yield source.
+        //      2. Calculate the shares minted with hyperdrive.convertToShares(baseAmount)
+        //      3. Calculate the final base amount with
+        //         finalBaseAmount =
+        //         hyperdrive.convertToShares(baseAmount).mulDown(vaultSharePrice)
+        //      With this in mind, we should be able to work back to this input
+        //      base amount with high precision if we do:
+        //      baseAmount = hyperdrive.convertToBase(finalBaseAmount.divDown(vaultSharePrice)
         if (_asBase) {
             // NOTE: Round up to overestimate the cost.
             cost = _hyperdrive.convertToBase(cost.divUp(vaultSharePrice));

test/integrations/matching/MatchingEngineV2IntegrationTest.t.sol

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: Apache-2.0
 pragma solidity 0.8.24;
 
-import { IMorpho, Market, MarketParams, Id } from "morpho-blue/src/interfaces/IMorpho.sol";
+import { IMorpho, MarketParams } from "morpho-blue/src/interfaces/IMorpho.sol";
 import { MarketParamsLib } from "morpho-blue/src/libraries/MarketParamsLib.sol";
 import { MorphoBlueConversions } from "../../../contracts/src/instances/morpho-blue/MorphoBlueConversions.sol";
 import { MorphoBlueHyperdrive } from "../../../contracts/src/instances/morpho-blue/MorphoBlueHyperdrive.sol";

test/units/matching/HyperdriveMatchingEngineV2Test.t.sol

@@ -575,9 +575,9 @@ contract HyperdriveMatchingEngineV2Test is HyperdriveTest {
     /// @dev Fuzzing test to verify TOKEN_AMOUNT_BUFFER is sufficient
     function testFuzz_tokenAmountBuffer(uint256 bondAmount) public {
         bondAmount = bound(bondAmount, 100e18, 1_000_000e18);
-        uint256 fundAmount1 = bondAmount / 2;
-        (, uint256 cost) = _calculateMintCost(bondAmount, true);
-        uint256 fundAmount2 = cost + 10 - fundAmount1;
+        // Ensure the fund is way more than sufficient
+        uint256 fundAmount1 = bondAmount * 2;
+        uint256 fundAmount2 = fundAmount1;
 
         // Create orders
         IHyperdriveMatchingEngineV2.OrderIntent
@@ -1063,55 +1063,4 @@ contract HyperdriveMatchingEngineV2Test is HyperdriveTest {
         (uint8 v, bytes32 r, bytes32 s) = vm.sign(privateKey, digest);
         return abi.encodePacked(r, s, v);
     }
-
-    /// @dev Calculates the cost and parameters for minting positions.
-    /// @param _bondMatchAmount The amount of bonds to mint.
-    /// @param _asBase Whether the cost is in terms of base.
-    /// @return maturityTime The maturity time for new positions.
-    /// @return cost The total cost including fees.
-    function _calculateMintCost(
-        uint256 _bondMatchAmount,
-        bool _asBase
-    ) internal view returns (uint256 maturityTime, uint256 cost) {
-        // Get pool configuration.
-        IHyperdrive.PoolConfig memory config = hyperdrive.getPoolConfig();
-
-        // Calculate checkpoint and maturity time.
-        uint256 latestCheckpoint = hyperdrive.latestCheckpoint();
-        maturityTime = latestCheckpoint + config.positionDuration;
-
-        // Get vault share prices.
-        uint256 vaultSharePrice = hyperdrive.convertToBase(1e18);
-        uint256 openVaultSharePrice = hyperdrive
-            .getCheckpoint(latestCheckpoint)
-            .vaultSharePrice;
-        if (openVaultSharePrice == 0) {
-            openVaultSharePrice = vaultSharePrice;
-        }
-
-        // Calculate the required fund amount.
-        // NOTE: Round the required fund amount up to overestimate the cost.
-        cost = _bondMatchAmount.mulDivUp(
-            vaultSharePrice.max(openVaultSharePrice),
-            openVaultSharePrice
-        );
-
-        // Add flat fee.
-        // NOTE: Round the flat fee calculation up to match other flows.
-        uint256 flatFee = _bondMatchAmount.mulUp(config.fees.flat);
-        cost += flatFee;
-
-        // Add governance fee.
-        // NOTE: Round the governance fee calculation down to match other flows.
-        uint256 governanceFee = 2 * flatFee.mulDown(config.fees.governanceLP);
-        cost += governanceFee;
-
-        if (_asBase) {
-            // NOTE: Round up to overestimate the cost.
-            cost = hyperdrive.convertToBase(cost.divUp(vaultSharePrice));
-        } else {
-            // NOTE: Round up to overestimate the cost.
-            cost = cost.divUp(vaultSharePrice);
-        }
-    }
 }