SqrtPriceMathEchidnaTest.sol

// SPDX-License-Identifier: UNLICENSED
pragma solidity =0.7.6;

import '../libraries/FullMath.sol';
import '../libraries/SqrtPriceMath.sol';
import '../libraries/FixedPoint96.sol';

contract SqrtPriceMathEchidnaTest {
    function mulDivRoundingUpInvariants(
        uint256 x,
        uint256 y,
        uint256 z
    ) external pure {
        require(z > 0);
        uint256 notRoundedUp = FullMath.mulDiv(x, y, z);
        uint256 roundedUp = FullMath.mulDivRoundingUp(x, y, z);
        assert(roundedUp >= notRoundedUp);
        assert(roundedUp - notRoundedUp < 2);
        if (roundedUp - notRoundedUp == 1) {
            assert(mulmod(x, y, z) > 0);
        } else {
            assert(mulmod(x, y, z) == 0);
        }
    }

    function getNextSqrtPriceFromInputInvariants(
        uint160 sqrtP,
        uint128 liquidity,
        uint256 amountIn,
        bool zeroForOne
    ) external pure {
        uint160 sqrtQ = SqrtPriceMath.getNextSqrtPriceFromInput(sqrtP, liquidity, amountIn, zeroForOne);

        if (zeroForOne) {
            assert(sqrtQ <= sqrtP);
            assert(amountIn >= SqrtPriceMath.getAmount0Delta(sqrtQ, sqrtP, liquidity, true));
        } else {
            assert(sqrtQ >= sqrtP);
            assert(amountIn >= SqrtPriceMath.getAmount1Delta(sqrtP, sqrtQ, liquidity, true));
        }
    }

    function getNextSqrtPriceFromOutputInvariants(
        uint160 sqrtP,
        uint128 liquidity,
        uint256 amountOut,
        bool zeroForOne
    ) external pure {
        uint160 sqrtQ = SqrtPriceMath.getNextSqrtPriceFromOutput(sqrtP, liquidity, amountOut, zeroForOne);

        if (zeroForOne) {
            assert(sqrtQ <= sqrtP);
            assert(amountOut <= SqrtPriceMath.getAmount1Delta(sqrtQ, sqrtP, liquidity, false));
        } else {
            assert(sqrtQ > 0); // this has to be true, otherwise we need another require
            assert(sqrtQ >= sqrtP);
            assert(amountOut <= SqrtPriceMath.getAmount0Delta(sqrtP, sqrtQ, liquidity, false));
        }
    }

    function getNextSqrtPriceFromAmount0RoundingUpInvariants(
        uint160 sqrtPX96,
        uint128 liquidity,
        uint256 amount,
        bool add
    ) external pure {
        require(sqrtPX96 > 0);
        require(liquidity > 0);
        uint160 sqrtQX96 = SqrtPriceMath.getNextSqrtPriceFromAmount0RoundingUp(sqrtPX96, liquidity, amount, add);

        if (add) {
            assert(sqrtQX96 <= sqrtPX96);
        } else {
            assert(sqrtQX96 >= sqrtPX96);
        }

        if (amount == 0) {
            assert(sqrtPX96 == sqrtQX96);
        }
    }

    function getNextSqrtPriceFromAmount1RoundingDownInvariants(
        uint160 sqrtPX96,
        uint128 liquidity,
        uint256 amount,
        bool add
    ) external pure {
        require(sqrtPX96 > 0);
        require(liquidity > 0);
        uint160 sqrtQX96 = SqrtPriceMath.getNextSqrtPriceFromAmount1RoundingDown(sqrtPX96, liquidity, amount, add);

        if (add) {
            assert(sqrtQX96 >= sqrtPX96);
        } else {
            assert(sqrtQX96 <= sqrtPX96);
        }

        if (amount == 0) {
            assert(sqrtPX96 == sqrtQX96);
        }
    }

    function getAmount0DeltaInvariants(
        uint160 sqrtP,
        uint160 sqrtQ,
        uint128 liquidity
    ) external pure {
        require(sqrtP > 0 && sqrtQ > 0);

        uint256 amount0Down = SqrtPriceMath.getAmount0Delta(sqrtQ, sqrtP, liquidity, false);
        assert(amount0Down == SqrtPriceMath.getAmount0Delta(sqrtP, sqrtQ, liquidity, false));

        uint256 amount0Up = SqrtPriceMath.getAmount0Delta(sqrtQ, sqrtP, liquidity, true);
        assert(amount0Up == SqrtPriceMath.getAmount0Delta(sqrtP, sqrtQ, liquidity, true));

        assert(amount0Down <= amount0Up);
        // diff is 0 or 1
        assert(amount0Up - amount0Down < 2);
    }

    // ensure that chained division is always equal to the full-precision case for
    // liquidity * (sqrt(P) - sqrt(Q)) / (sqrt(P) * sqrt(Q))
    function getAmount0DeltaEquivalency(
        uint160 sqrtP,
        uint160 sqrtQ,
        uint128 liquidity,
        bool roundUp
    ) external pure {
        require(sqrtP >= sqrtQ);
        require(sqrtP > 0 && sqrtQ > 0);
        require((sqrtP * sqrtQ) / sqrtP == sqrtQ);

        uint256 numerator1 = uint256(liquidity) << FixedPoint96.RESOLUTION;
        uint256 numerator2 = sqrtP - sqrtQ;
        uint256 denominator = uint256(sqrtP) * sqrtQ;

        uint256 safeResult =
            roundUp
                ? FullMath.mulDivRoundingUp(numerator1, numerator2, denominator)
                : FullMath.mulDiv(numerator1, numerator2, denominator);
        uint256 fullResult = SqrtPriceMath.getAmount0Delta(sqrtQ, sqrtP, liquidity, roundUp);

        assert(safeResult == fullResult);
    }

    function getAmount1DeltaInvariants(
        uint160 sqrtP,
        uint160 sqrtQ,
        uint128 liquidity
    ) external pure {
        require(sqrtP > 0 && sqrtQ > 0);

        uint256 amount1Down = SqrtPriceMath.getAmount1Delta(sqrtP, sqrtQ, liquidity, false);
        assert(amount1Down == SqrtPriceMath.getAmount1Delta(sqrtQ, sqrtP, liquidity, false));

        uint256 amount1Up = SqrtPriceMath.getAmount1Delta(sqrtP, sqrtQ, liquidity, true);
        assert(amount1Up == SqrtPriceMath.getAmount1Delta(sqrtQ, sqrtP, liquidity, true));

        assert(amount1Down <= amount1Up);
        // diff is 0 or 1
        assert(amount1Up - amount1Down < 2);
    }

    function getAmount0DeltaSignedInvariants(
        uint160 sqrtP,
        uint160 sqrtQ,
        int128 liquidity
    ) external pure {
        require(sqrtP > 0 && sqrtQ > 0);

        int256 amount0 = SqrtPriceMath.getAmount0Delta(sqrtQ, sqrtP, liquidity);
        if (liquidity < 0) assert(amount0 <= 0);
        if (liquidity > 0) {
            if (sqrtP == sqrtQ) assert(amount0 == 0);
            else assert(amount0 > 0);
        }
        if (liquidity == 0) assert(amount0 == 0);
    }

    function getAmount1DeltaSignedInvariants(
        uint160 sqrtP,
        uint160 sqrtQ,
        int128 liquidity
    ) external pure {
        require(sqrtP > 0 && sqrtQ > 0);

        int256 amount1 = SqrtPriceMath.getAmount1Delta(sqrtP, sqrtQ, liquidity);
        if (liquidity < 0) assert(amount1 <= 0);
        if (liquidity > 0) {
            if (sqrtP == sqrtQ) assert(amount1 == 0);
            else assert(amount1 > 0);
        }
        if (liquidity == 0) assert(amount1 == 0);
    }

    function getOutOfRangeMintInvariants(
        uint160 sqrtA,
        uint160 sqrtB,
        int128 liquidity
    ) external pure {
        require(sqrtA > 0 && sqrtB > 0);
        require(liquidity > 0);

        int256 amount0 = SqrtPriceMath.getAmount0Delta(sqrtA, sqrtB, liquidity);
        int256 amount1 = SqrtPriceMath.getAmount1Delta(sqrtA, sqrtB, liquidity);

        if (sqrtA == sqrtB) {
            assert(amount0 == 0);
            assert(amount1 == 0);
        } else {
            assert(amount0 > 0);
            assert(amount1 > 0);
        }
    }

    function getInRangeMintInvariants(
        uint160 sqrtLower,
        uint160 sqrtCurrent,
        uint160 sqrtUpper,
        int128 liquidity
    ) external pure {
        require(sqrtLower > 0);
        require(sqrtLower < sqrtUpper);
        require(sqrtLower <= sqrtCurrent && sqrtCurrent <= sqrtUpper);
        require(liquidity > 0);

        int256 amount0 = SqrtPriceMath.getAmount0Delta(sqrtCurrent, sqrtUpper, liquidity);
        int256 amount1 = SqrtPriceMath.getAmount1Delta(sqrtLower, sqrtCurrent, liquidity);

        assert(amount0 > 0 || amount1 > 0);
    }
}