test(libraries): add math library unit tests

test/Math.t.sol

@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.36;
+
+import {Test} from "forge-std/Test.sol";
+import {Math} from "../src/libraries/Math.sol";
+import {FluxLibrary} from "../src/libraries/FluxLibrary.sol";
+
+contract LibHarness {
+    function quote(uint256 amountA, uint256 reserveA, uint256 reserveB) external pure returns (uint256) {
+        return FluxLibrary.quote(amountA, reserveA, reserveB);
+    }
+
+    function getAmountOut(uint256 amountIn, uint256 reserveIn, uint256 reserveOut) external pure returns (uint256) {
+        return FluxLibrary.getAmountOut(amountIn, reserveIn, reserveOut);
+    }
+}
+
+contract MathTest is Test {
+    LibHarness private harness;
+
+    function setUp() public {
+        harness = new LibHarness();
+    }
+
+    function testSqrtSmallValues() public pure {
+        assertEq(Math.sqrt(0), 0);
+        assertEq(Math.sqrt(1), 1);
+        assertEq(Math.sqrt(2), 1);
+        assertEq(Math.sqrt(3), 1);
+        assertEq(Math.sqrt(4), 2);
+        assertEq(Math.sqrt(15), 3);
+        assertEq(Math.sqrt(16), 4);
+        assertEq(Math.sqrt(99), 9);
+        assertEq(Math.sqrt(100), 10);
+    }
+
+    function testSqrtLargeValue() public pure {
+        assertEq(Math.sqrt(100e18 * 400e18), 2e20);
+        assertEq(Math.sqrt(type(uint256).max), 340282366920938463463374607431768211455);
+    }
+
+    function testMin() public pure {
+        assertEq(Math.min(3, 7), 3);
+        assertEq(Math.min(7, 3), 3);
+        assertEq(Math.min(5, 5), 5);
+    }
+
+    function testQuote() public pure {
+        assertEq(FluxLibrary.quote(10e18, 100e18, 400e18), 40e18);
+        assertEq(FluxLibrary.quote(50e18, 100e18, 400e18), 200e18);
+    }
+
+    function testGetAmountOut() public pure {
+        assertEq(FluxLibrary.getAmountOut(10e18, 100e18, 400e18), 36264435755205965263);
+    }
+
+    function testGetAmountIn() public pure {
+        assertEq(FluxLibrary.getAmountIn(50e18, 100e18, 400e18), 14328700386874910446);
+    }
+
+    function testQuoteRevertsOnZeroLiquidity() public {
+        vm.expectRevert(bytes("FluxLibrary: INSUFFICIENT_LIQUIDITY"));
+        harness.quote(10e18, 0, 400e18);
+    }
+
+    function testGetAmountOutRevertsOnZeroInput() public {
+        vm.expectRevert(bytes("FluxLibrary: INSUFFICIENT_INPUT_AMOUNT"));
+        harness.getAmountOut(0, 100e18, 400e18);
+    }
+}