govstaking/test/helpers/PercentAssertions.sol

PercentAssertions.sol

@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+pragma solidity ^0.8.23;
+
+import {Test} from "forge-std/Test.sol";
+
+contract PercentAssertions is Test {
+  // Because there will be (expected) rounding errors in the amount of rewards earned, this helper
+  // checks that the truncated number is lesser and within 1% of the expected number.
+  function assertLteWithinOnePercent(uint256 a, uint256 b) public {
+    if (a > b) {
+      emit log("Error: a <= b not satisfied");
+      emit log_named_uint("  Expected", b);
+      emit log_named_uint("    Actual", a);
+
+      fail();
+    }
+
+    uint256 minBound = (b * 9900) / 10_000;
+
+    if (a < minBound) {
+      emit log("Error: a >= 0.99 * b not satisfied");
+      emit log_named_uint("  Expected", b);
+      emit log_named_uint("    Actual", a);
+      emit log_named_uint("  minBound", minBound);
+
+      fail();
+    }
+  }
+
+  function _percentOf(uint256 _amount, uint256 _percent) public pure returns (uint256) {
+    // For cases where the percentage is less than 100, we calculate the percentage by
+    // taking the inverse percentage and subtracting it. This effectively rounds _up_ the
+    // value by putting the truncation on the opposite side. For example, 92% of 555 is 510.6.
+    // Calculating it in this way would yield (555 - 44) = 511, instead of 510.
+    if (_percent < 100) return _amount - ((100 - _percent) * _amount) / 100;
+    else return (_percent * _amount) / 100;
+  }
+
+  // This helper is for normal rounding errors, i.e. if the number might be truncated down by 1
+  function assertLteWithinOneUnit(uint256 a, uint256 b) public {
+    if (a > b) {
+      emit log("Error: a <= b not satisfied");
+      emit log_named_uint("  Expected", b);
+      emit log_named_uint("    Actual", a);
+
+      fail();
+    }
+
+    uint256 minBound = b - 1;
+
+    if (!((a == b) || (a == minBound))) {
+      emit log("Error: a == b || a  == b-1");
+      emit log_named_uint("  Expected", b);
+      emit log_named_uint("    Actual", a);
+
+      fail();
+    }
+  }
+}