From 9568095c37a9e24480a9a9fe68940824b1242735 Mon Sep 17 00:00:00 2001
From: Hayden Shively <17186559+haydenshively@users.noreply.github.com>
Date: Mon, 18 Sep 2023 00:13:14 -0500
Subject: [PATCH] Fix flakey invariant and add mathematic require in Lender
 (#162)

---
 core/src/Lender.sol                         | 2 +-
 core/test/invariants/LenderInvariants.t.sol | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/core/src/Lender.sol b/core/src/Lender.sol
index effdaf47..0b58be51 100644
--- a/core/src/Lender.sol
+++ b/core/src/Lender.sol
@@ -61,7 +61,7 @@ contract Lender is Ledger {
 
     /// @notice Sets the `rateModel` and `reserveFactor`. Only the `FACTORY` can call this.
     function setRateModelAndReserveFactor(IRateModel rateModel_, uint8 reserveFactor_) external {
-        require(msg.sender == address(FACTORY));
+        require(msg.sender == address(FACTORY) && reserveFactor_ > 0);
         rateModel = rateModel_;
         reserveFactor = reserveFactor_;
     }
diff --git a/core/test/invariants/LenderInvariants.t.sol b/core/test/invariants/LenderInvariants.t.sol
index e26c5986..f21d9ea9 100644
--- a/core/test/invariants/LenderInvariants.t.sol
+++ b/core/test/invariants/LenderInvariants.t.sol
@@ -199,9 +199,9 @@ contract LenderInvariantsTest is Test {
             address user = lenderHarness.holders(i);
 
             // NOTE: As price per share increases (i.e., each share converts to more and more underlying assets),
-            // this assertion may become flakey due to rounding. Allowing for rounding error of 2 seems sufficient
+            // this assertion may become flakey due to rounding. Allowing for rounding error of 3 seems sufficient
             // in our testing. Just make sure the contract itself never assumes principle < underlyingBalance
-            assertLe(lender.principleOf(user), lender.underlyingBalance(user) + 2);
+            assertLe(lender.principleOf(user), lender.underlyingBalance(user) + 3);
         }
     }