Section 6 ThunderLoan Audit Storage Collision POC

[EchoSpr]

After writing this test function

function testUpgradeBreaks() public {
        uint256 feeBeforeUpgrade = thunderLoan.getFee();
        vm.startPrank(thunderLoan.owner());
        ThunderLoanUpgraded upgraded = new ThunderLoanUpgraded();
        thunderLoan.upgradeToAndCall(address(upgraded), "");
        uint256 feeAfterUpgrade = thunderLoan.getFee();
        vm.stopPrank();

        console2.log("Fee Before: ", feeBeforeUpgrade);
        console2.log("Fee After: ", feeAfterUpgrade);
        
        assert(feeBeforeUpgrade != feeAfterUpgrade);
    }

I am getting this error

Failing tests:
Encountered 1 failing test in test/unit/ThunderLoanTest.t.sol:ThunderLoanTest
[FAIL. Reason: revert: Address: low-level delegate call failed] testUpgradeBreaks()

I am not sure how to solve this error.

[johnsonstephan]

Spoiler

a. Review the test suite in the audit-data branch

Else

b. Clone the audit-data branch, run the tests, and determine where the gap in your test is