basic test environment works

src/Util.sol

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+// SPDX-License-Identifier: UNLICENSED
+pragma solidity =0.7.6;
+pragma abicoder v2;
+
+library Util {
+    function roundTick(int24 tick, int24 window) public pure returns (int24) {
+        // NOTE: we round half toward zero
+        int24 mod = tick % window;
+        if (tick < 0)
+            return - mod <= window / 2 ? tick - mod : tick - (window + mod);
+        else
+            return mod > window / 2 ? tick + (window - mod) : tick - mod;
+    }
+}