Merge pull request #85 from morpho-org/fix/BC-computation

fix: Borrow capacity computation
morpho-org · Aug 15, 2023 · a5584e8 · a5584e8
2 parents 7cbefc7 + 2c9b223
commit a5584e8
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Showing 6 changed files with 16 additions and 11 deletions.
diff --git a/src/MorphoAaveV3DataHolder.ts b/src/MorphoAaveV3DataHolder.ts
@@ -106,7 +106,7 @@ export class MorphoAaveV3DataHolder {
         );
 
         borrowCapacity = borrowCapacity.add(
-          PercentMath.percentMul(
+          this.__MATH__.percentMulDown(
             collateralReduced,
             marketConfig.borrowableFactor
           )

diff --git a/src/simulation/MorphoAaveV3Simulator.ts b/src/simulation/MorphoAaveV3Simulator.ts
@@ -796,7 +796,8 @@ export class MorphoAaveV3Simulator extends MorphoAaveV3DataEmitter {
         operation
       );
 
-    const totalCollateral = userMarketData.totalCollateral.add(amount);
+    // Since it's gonna be scaled and unscaled, the value is gonna be reduced by one
+    const totalCollateral = userMarketData.totalCollateral.add(amount.sub(1));
 
     const newUserMarketData: UserMarketData = {
       ...userMarketData,

diff --git a/tests/e2e/bulker.test.ts b/tests/e2e/bulker.test.ts
@@ -541,8 +541,8 @@ describe("MorphoAaveV3 Bulker", () => {
         weth.address,
         morphoUser.address
       );
-      expect(ma3Balance).to.equal(
-        amountToBorrow,
+      expect(
+        approxEqual(ma3Balance, amountToBorrow, 1),
         `expected ma3 weth balance is ${amountToBorrow}, received ${ma3Balance}`
       );
 

diff --git a/tests/helpers/bn.ts b/tests/helpers/bn.ts
@@ -2,8 +2,12 @@ import { BigNumber, BigNumberish } from "ethers";
 
 const APPROX_EQUAL_THRESHOLD = 10;
 
-export const approxEqual = (a: BigNumberish, b: BigNumberish) => {
+export const approxEqual = (
+  a: BigNumberish,
+  b: BigNumberish,
+  delta = APPROX_EQUAL_THRESHOLD
+) => {
   a = BigNumber.from(a);
   b = BigNumber.from(b);
-  return a.sub(b).abs().lte(APPROX_EQUAL_THRESHOLD);
+  return a.sub(b).abs().lte(delta);
 };
diff --git a/tests/units/computeUserData.test.ts b/tests/units/computeUserData.test.ts
@@ -131,7 +131,7 @@ describe("computeUserData", () => {
           .div(underlyingUnit);
 
         expectedBorrowCapacity = expectedBorrowCapacity.add(
-          PercentMath.percentMul(
+          __MATHS__.percentMulDown(
             userCollateralUSD.mul(LT_LOWER_BOUND.sub(1)).div(LT_LOWER_BOUND), // the borrow capacity is reduced by a small amount
             borrowableFactor
           )

diff --git a/tests/units/simulator.test.ts b/tests/units/simulator.test.ts
@@ -189,9 +189,9 @@ describe("Simulator", () => {
       ]);
       await sleep(100);
 
-      const finalTotalCollateral = initialTotalCollateral.add(
-        supplyCollateralAmount
-      );
+      const finalTotalCollateral = initialTotalCollateral
+        .add(supplyCollateralAmount)
+        .sub(1);
       expect(totalCollateral).toBnEq(finalTotalCollateral);
     });
 
@@ -267,7 +267,7 @@ describe("Simulator", () => {
         TransactionType.borrow
       )!.amount;
 
-      const expectedBorrowCapacity = BigNumber.from("717673393785148514851485");
+      const expectedBorrowCapacity = BigNumber.from("717673393785138613861386");
       expect(initialBorrowCapacity).toBnEq(expectedBorrowCapacity);
 
       simulator.simulate([