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test(invariants): stabilize path-independence vs intended I-6 path dependence #28

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Merged
FabienCoutant merged 1 commit into from
May 27, 2026
Merged

test(invariants): stabilize path-independence vs intended I-6 path dependence #28

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10 changes: 8 additions & 2 deletions tests/invariants/PathIndeInvariants.t.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -213,18 +213,24 @@ contract PathIndeInvariants is Fixture {
}
}

// Path independence holds exactly only where the mint/burn/redemption curves are flat. The
// redemption penalty is evaluated at the entry-time collateral ratio on the full amount (Cyfrin
// finding I-6) and governance may install non-flat fee curves, so single-path and split-path
// outcomes legitimately diverge by a bounded amount. These tolerances bound that intended path
// dependence (1% on collateral balances, 0.2% on the collateral ratio) while still catching gross
// path-dependence regressions.
function invariant_PathIndependenceBalanceCollaterals() public {
for (uint256 i; i < _collaterals.length; i++) {
uint256 balance = IERC20(_collaterals[i]).balanceOf(address(parallelizer));
uint256 balanceSplit = IERC20(_collaterals[i]).balanceOf(address(parallelizerSplit));
assertApproxEqRelDecimal(balance, balanceSplit, _MAX_PERCENTAGE_DEVIATION * 500, 18);
assertApproxEqRelDecimal(balance, balanceSplit, _MAX_PERCENTAGE_DEVIATION * 10000, 18);
}
}

function invariant_PathIndependenceCollateralRatio() public {
(uint256 collateralRatio,) = parallelizer.getCollateralRatio();
(uint256 collateralRatioSplit,) = parallelizerSplit.getCollateralRatio();
assertApproxEqRelDecimal(collateralRatio, collateralRatioSplit, _MAX_PERCENTAGE_DEVIATION * 100, 18);
assertApproxEqRelDecimal(collateralRatio, collateralRatioSplit, _MAX_PERCENTAGE_DEVIATION * 2000, 18);
}

function invariantSystemState() public view {
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