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Add rule verifying flash loans increase share value #186

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Jul 23, 2025
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Add rule verifying flash loans increase share value #186

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18 changes: 18 additions & 0 deletions DEFI/LiquidityPool/certora/specs/Full.spec
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Original file line number Diff line number Diff line change
Expand Up @@ -254,6 +254,24 @@ rule flashLoanRevertConditions(env e){
assert isExpectedToRevert <=> lastReverted;
}

/// Validates that a flash loan generates yield by increase the value of each share (modulo rounding)
rule flashLoansGenerateYield(address receiver, uint amount) {
env e;
require e.msg.sender != currentContract;

uint assetsBefore = depositedAmount();
uint sharesBefore = totalSupply();
flashLoan(e, receiver, amount);
uint assetsAfter = depositedAmount();
uint sharesAfter = totalSupply();

// The total assets held by the contract must increase, while the number of shares remains constant.
// The yield might not be reflected in sharesToAmount due to the rounding.

assert assetsAfter > assetsBefore;
assert sharesAfter == sharesBefore;
}

/*
┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ Find and show a path for each method. │
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