53 lines
1.7 KiB
Solidity
53 lines
1.7 KiB
Solidity
// SPDX-License-Identifier: UNLICENSED
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pragma solidity =0.7.6;
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import '../libraries/SwapMath.sol';
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contract SwapMathEchidnaTest {
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function checkComputeSwapStepInvariants(
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uint160 sqrtPriceRaw,
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uint160 sqrtPriceTargetRaw,
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uint128 liquidity,
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int256 amountRemaining,
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uint24 feePips
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) external pure {
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require(sqrtPriceRaw > 0);
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require(sqrtPriceTargetRaw > 0);
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require(feePips > 0);
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require(feePips < 1e6);
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(uint160 sqrtQ, uint256 amountIn, uint256 amountOut, uint256 feeAmount) =
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SwapMath.computeSwapStep(sqrtPriceRaw, sqrtPriceTargetRaw, liquidity, amountRemaining, feePips);
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assert(amountIn <= type(uint256).max - feeAmount);
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if (amountRemaining < 0) {
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assert(amountOut <= uint256(-amountRemaining));
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} else {
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assert(amountIn + feeAmount <= uint256(amountRemaining));
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}
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if (sqrtPriceRaw == sqrtPriceTargetRaw) {
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assert(amountIn == 0);
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assert(amountOut == 0);
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assert(feeAmount == 0);
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assert(sqrtQ == sqrtPriceTargetRaw);
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}
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// didn't reach price target, entire amount must be consumed
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if (sqrtQ != sqrtPriceTargetRaw) {
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if (amountRemaining < 0) assert(amountOut == uint256(-amountRemaining));
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else assert(amountIn + feeAmount == uint256(amountRemaining));
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}
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// next price is between price and price target
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if (sqrtPriceTargetRaw <= sqrtPriceRaw) {
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assert(sqrtQ <= sqrtPriceRaw);
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assert(sqrtQ >= sqrtPriceTargetRaw);
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} else {
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assert(sqrtQ >= sqrtPriceRaw);
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assert(sqrtQ <= sqrtPriceTargetRaw);
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}
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}
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}
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