Create opt.sol

Author: gustavo-grieco

program-analysis/echidna/example/opt.sol

@@ -0,0 +1,34 @@
+pragma solidity ^0.8.0;
+
+contract TestDutchAuctionOptimization {
+    int256 maxPriceDifference;
+
+    function setMaxPriceDifference(
+        uint256 startPrice,
+        uint256 endPrice,
+        uint256 startTime,
+        uint256 endTime
+    ) public {
+        if (endTime < (startTime + 900)) {
+            revert();
+        }
+        if (startPrice <= endPrice) {
+            revert();
+        }
+        uint256 numerator = (startPrice - endPrice) *
+            (block.timestamp - startTime);
+        uint256 denominator = endTime - startTime;
+        uint256 stepDecrease = numerator / denominator;
+        uint256 currentAuctionPrice = startPrice - stepDecrease;
+        if (currentAuctionPrice < endPrice) {
+            maxPriceDifference = int256(endPrice - currentAuctionPrice);
+        }
+        if (currentAuctionPrice > startPrice) {
+            maxPriceDifference = int256(currentAuctionPrice - startPrice);
+        }
+    }
+
+    function echidna_opt_price_difference() public view returns (int256) {
+        return maxPriceDifference;
+    }
+}