harb/onchain/test/VWAPTracker.t.sol

// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.19;

import "forge-std/Test.sol";
import "../src/VWAPTracker.sol";

/**
 * @title VWAPTracker Test Suite
 * @notice Comprehensive tests for the VWAPTracker contract including:
 *         - Basic VWAP calculation functionality
 *         - Overflow handling in cumulative calculations
 *         - Adjusted VWAP with capital inefficiency
 *         - Volume weighted price accumulation
 */
contract MockVWAPTracker is VWAPTracker {
    function recordVolumeAndPrice(uint256 currentPriceX96, uint256 fee) external {
        _recordVolumeAndPrice(currentPriceX96, fee);
    }

    function resetVWAP() external {
        _resetVWAP();
    }
}

contract VWAPTrackerTest is Test {
    MockVWAPTracker vwapTracker;

    // Test constants
    uint256 constant SAMPLE_PRICE_X96 = 79228162514264337593543950336; // 1.0 in X96 format
    uint256 constant SAMPLE_FEE = 1 ether;
    uint256 constant CAPITAL_INEFFICIENCY = 5 * 10 ** 17; // 50%

    function setUp() public {
        vwapTracker = new MockVWAPTracker();
    }

    // ========================================
    // BASIC VWAP FUNCTIONALITY TESTS
    // ========================================

    function testInitialState() public {
        assertEq(vwapTracker.cumulativeVolumeWeightedPriceX96(), 0, "Initial cumulative VWAP should be zero");
        assertEq(vwapTracker.cumulativeVolume(), 0, "Initial cumulative volume should be zero");
        assertEq(vwapTracker.getVWAP(), 0, "Initial VWAP should be zero");
        assertEq(vwapTracker.getAdjustedVWAP(CAPITAL_INEFFICIENCY), 0, "Initial adjusted VWAP should be zero");
    }

    function testSinglePriceRecording() public {
        vwapTracker.recordVolumeAndPrice(SAMPLE_PRICE_X96, SAMPLE_FEE);

        uint256 expectedVolume = SAMPLE_FEE * 100; // Fee is 1% of volume
        uint256 expectedVWAP = SAMPLE_PRICE_X96;

        assertEq(vwapTracker.cumulativeVolume(), expectedVolume, "Volume should be recorded correctly");
        assertEq(vwapTracker.getVWAP(), expectedVWAP, "VWAP should equal the single price");

        uint256 adjustedVWAP = vwapTracker.getAdjustedVWAP(CAPITAL_INEFFICIENCY);
        uint256 expectedAdjustedVWAP = (7 * expectedVWAP / 10) + (expectedVWAP * CAPITAL_INEFFICIENCY / 10 ** 18);
        assertEq(adjustedVWAP, expectedAdjustedVWAP, "Adjusted VWAP should be calculated correctly");
    }

    function testMultiplePriceRecording() public {
        // Record first price
        uint256 price1 = SAMPLE_PRICE_X96;
        uint256 fee1 = 1 ether;
        vwapTracker.recordVolumeAndPrice(price1, fee1);

        // Record second price (double the first)
        uint256 price2 = SAMPLE_PRICE_X96 * 2;
        uint256 fee2 = 2 ether;
        vwapTracker.recordVolumeAndPrice(price2, fee2);

        uint256 volume1 = fee1 * 100;
        uint256 volume2 = fee2 * 100;
        uint256 expectedTotalVolume = volume1 + volume2;

        uint256 expectedVWAP = (price1 * volume1 + price2 * volume2) / expectedTotalVolume;

        assertEq(
            vwapTracker.cumulativeVolume(), expectedTotalVolume, "Total volume should be sum of individual volumes"
        );
        assertEq(vwapTracker.getVWAP(), expectedVWAP, "VWAP should be correctly weighted average");
    }

    function testVWAPReset() public {
        vwapTracker.recordVolumeAndPrice(SAMPLE_PRICE_X96, SAMPLE_FEE);

        assertGt(vwapTracker.getVWAP(), 0, "VWAP should be non-zero after recording");

        vwapTracker.resetVWAP();

        assertEq(vwapTracker.cumulativeVolumeWeightedPriceX96(), 0, "Cumulative VWAP should be reset to zero");
        assertEq(vwapTracker.cumulativeVolume(), 0, "Cumulative volume should be reset to zero");
        assertEq(vwapTracker.getVWAP(), 0, "VWAP should be zero after reset");
    }

    // ========================================
    // OVERFLOW HANDLING TESTS
    // ========================================

    function testOverflowHandling() public {
        // Set cumulative values to near overflow
        vm.store(
            address(vwapTracker),
            bytes32(uint256(0)), // cumulativeVolumeWeightedPriceX96 storage slot
            bytes32(uint256(10 ** 70 + 1))
        );

        vm.store(
            address(vwapTracker),
            bytes32(uint256(1)), // cumulativeVolume storage slot
            bytes32(uint256(10 ** 40))
        );

        uint256 beforeVWAP = vwapTracker.cumulativeVolumeWeightedPriceX96();
        uint256 beforeVolume = vwapTracker.cumulativeVolume();

        assertGt(beforeVWAP, 10 ** 70, "Initial cumulative VWAP should be above overflow threshold");

        // Record a price that should trigger overflow handling
        vwapTracker.recordVolumeAndPrice(SAMPLE_PRICE_X96, SAMPLE_FEE);

        uint256 afterVWAP = vwapTracker.cumulativeVolumeWeightedPriceX96();
        uint256 afterVolume = vwapTracker.cumulativeVolume();

        // Values should be compressed (smaller than before)
        assertLt(afterVWAP, beforeVWAP, "VWAP should be compressed after overflow");
        assertLt(afterVolume, beforeVolume, "Volume should be compressed after overflow");

        // But still maintain reasonable ratio
        uint256 calculatedVWAP = afterVWAP / afterVolume;
        assertGt(calculatedVWAP, 0, "Calculated VWAP should be positive after overflow handling");
        assertLt(calculatedVWAP, 10 ** 40, "Calculated VWAP should be within reasonable bounds");
    }

    function testOverflowCompressionRatio() public {
        // Test that compression preserves historical significance (eternal memory for dormant whale protection)
        uint256 initialVWAP = 10 ** 70 + 1;
        uint256 initialVolume = 10 ** 40;

        vm.store(address(vwapTracker), bytes32(uint256(0)), bytes32(initialVWAP));
        vm.store(address(vwapTracker), bytes32(uint256(1)), bytes32(initialVolume));

        uint256 expectedRatioBefore = initialVWAP / initialVolume; // ≈ 10^30

        vwapTracker.recordVolumeAndPrice(SAMPLE_PRICE_X96, SAMPLE_FEE);

        uint256 finalVWAP = vwapTracker.cumulativeVolumeWeightedPriceX96();
        uint256 finalVolume = vwapTracker.cumulativeVolume();
        uint256 actualRatio = finalVWAP / finalVolume;

        // CRITICAL: The fixed compression algorithm should preserve historical significance
        // Maximum compression factor is 1000x, so historical data should still dominate
        // This is essential for dormant whale protection - historical prices must retain weight
        
        assertGt(actualRatio, 0, "Compression should maintain positive ratio");
        
        // Historical data should still dominate after compression (not the new price)
        // With 1000x max compression, historical ratio should be preserved within reasonable bounds
        uint256 tolerance = expectedRatioBefore / 2; // 50% tolerance for new data influence
        assertGt(actualRatio, expectedRatioBefore - tolerance, "Historical data should still dominate after compression");
        assertLt(actualRatio, expectedRatioBefore + tolerance, "Historical data should still dominate after compression");
        
        // Verify the ratio is NOT close to the new price (which would indicate broken dormant whale protection)
        uint256 newPriceRatio = SAMPLE_PRICE_X96; // ≈ 7.9 * 10^28, much smaller than historical ratio
        assertGt(actualRatio, newPriceRatio * 2, "VWAP should not be dominated by new price - dormant whale protection");
    }

    function testDormantWhaleProtection() public {
        // Test that VWAP maintains historical memory to prevent dormant whale attacks
        
        // Phase 1: Establish historical low prices with significant volume
        uint256 cheapPrice = SAMPLE_PRICE_X96 / 10; // 10x cheaper than sample
        uint256 historicalVolume = 100 ether; // Large volume to establish strong historical weight
        
        // Build up significant historical data at cheap prices
        for (uint i = 0; i < 10; i++) {
            vwapTracker.recordVolumeAndPrice(cheapPrice, historicalVolume);
        }
        
        uint256 earlyVWAP = vwapTracker.getVWAP();
        assertEq(earlyVWAP, cheapPrice, "Early VWAP should equal the cheap price");
        
        // Phase 2: Simulate large historical data that maintains the cheap price ratio
        // Set values that will trigger compression while preserving the cheap price VWAP
        uint256 historicalVWAPValue = 10 ** 70 + 1; // Trigger compression threshold
        uint256 adjustedVolume = historicalVWAPValue / cheapPrice; // Maintain cheap price ratio
        
        vm.store(address(vwapTracker), bytes32(uint256(0)), bytes32(historicalVWAPValue));
        vm.store(address(vwapTracker), bytes32(uint256(1)), bytes32(adjustedVolume));
        
        // Verify historical cheap price is preserved
        uint256 preWhaleVWAP = vwapTracker.getVWAP();
        assertApproxEqRel(preWhaleVWAP, cheapPrice, 0.01e18, "Historical cheap price should be preserved"); // 1% tolerance
        
        // Phase 3: Whale tries to sell at high price (this should trigger compression)
        uint256 expensivePrice = SAMPLE_PRICE_X96 * 10; // 10x more expensive
        uint256 whaleVolume = 10 ether; // Whale's volume
        vwapTracker.recordVolumeAndPrice(expensivePrice, whaleVolume);
        
        uint256 finalVWAP = vwapTracker.getVWAP();
        
        // CRITICAL: Final VWAP should still be much closer to historical cheap price
        // Even after compression, historical data should provide protection
        assertLt(finalVWAP, cheapPrice * 2, "VWAP should remain close to historical prices despite expensive whale trade");
        
        // The whale's expensive price should not dominate the VWAP
        uint256 whaleInfluenceRatio = (finalVWAP * 100) / cheapPrice; // How much did whale inflate the price?
        assertLt(whaleInfluenceRatio, 300, "Whale should not be able to inflate VWAP by more than 3x from historical levels");
        
        console.log("Historical cheap price:", cheapPrice);
        console.log("Whale expensive price:", expensivePrice);
        console.log("Final VWAP:", finalVWAP);
        console.log("VWAP inflation from whale:", whaleInfluenceRatio, "% (should be limited)");
    }

    // ========================================
    // ADJUSTED VWAP TESTS
    // ========================================

    function testAdjustedVWAPCalculation() public {
        vwapTracker.recordVolumeAndPrice(SAMPLE_PRICE_X96, SAMPLE_FEE);

        uint256 baseVWAP = vwapTracker.getVWAP();
        uint256 adjustedVWAP = vwapTracker.getAdjustedVWAP(CAPITAL_INEFFICIENCY);

        uint256 expectedAdjustedVWAP = (7 * baseVWAP / 10) + (baseVWAP * CAPITAL_INEFFICIENCY / 10 ** 18);

        assertEq(adjustedVWAP, expectedAdjustedVWAP, "Adjusted VWAP should match expected calculation");
        // With 50% capital inefficiency: 70% + 50% = 120% of base VWAP
        assertGt(adjustedVWAP, baseVWAP, "Adjusted VWAP should be greater than base VWAP with 50% capital inefficiency");
    }

    function testAdjustedVWAPWithZeroCapitalInefficiency() public {
        vwapTracker.recordVolumeAndPrice(SAMPLE_PRICE_X96, SAMPLE_FEE);

        uint256 baseVWAP = vwapTracker.getVWAP();
        uint256 adjustedVWAP = vwapTracker.getAdjustedVWAP(0);

        uint256 expectedAdjustedVWAP = 7 * baseVWAP / 10;

        assertEq(
            adjustedVWAP, expectedAdjustedVWAP, "Adjusted VWAP with zero capital inefficiency should be 70% of base"
        );
    }

    function testAdjustedVWAPWithMaxCapitalInefficiency() public {
        vwapTracker.recordVolumeAndPrice(SAMPLE_PRICE_X96, SAMPLE_FEE);

        uint256 baseVWAP = vwapTracker.getVWAP();
        uint256 adjustedVWAP = vwapTracker.getAdjustedVWAP(10 ** 18); // 100% capital inefficiency

        uint256 expectedAdjustedVWAP = (7 * baseVWAP / 10) + baseVWAP;

        assertEq(
            adjustedVWAP, expectedAdjustedVWAP, "Adjusted VWAP with max capital inefficiency should be 170% of base"
        );
    }

    // ========================================
    // FUZZ TESTS
    // ========================================

    function testFuzzVWAPCalculation(uint256 price, uint256 fee) public {
        // Bound inputs to reasonable ranges
        price = bound(price, 1000, type(uint128).max);
        fee = bound(fee, 1000, type(uint64).max);

        vwapTracker.recordVolumeAndPrice(price, fee);

        uint256 expectedVolume = fee * 100;
        uint256 expectedVWAP = price;

        assertEq(vwapTracker.cumulativeVolume(), expectedVolume, "Volume should be recorded correctly");
        assertEq(vwapTracker.getVWAP(), expectedVWAP, "VWAP should equal the single price");

        // Test that adjusted VWAP is within reasonable bounds
        uint256 adjustedVWAP = vwapTracker.getAdjustedVWAP(CAPITAL_INEFFICIENCY);
        assertGt(adjustedVWAP, 0, "Adjusted VWAP should be positive");
        assertLt(adjustedVWAP, price * 2, "Adjusted VWAP should be less than twice the base price");
    }

    function testConcreteMultipleRecordings() public {
        // Test with concrete values to ensure deterministic behavior
        uint256[] memory prices = new uint256[](3);
        uint256[] memory fees = new uint256[](3);

        prices[0] = 100000;
        prices[1] = 200000;
        prices[2] = 150000;

        fees[0] = 1000;
        fees[1] = 2000;
        fees[2] = 1500;

        uint256 totalVWAP = 0;
        uint256 totalVolume = 0;

        for (uint256 i = 0; i < prices.length; i++) {
            uint256 volume = fees[i] * 100;
            totalVWAP += prices[i] * volume;
            totalVolume += volume;

            vwapTracker.recordVolumeAndPrice(prices[i], fees[i]);
        }

        uint256 expectedVWAP = totalVWAP / totalVolume;
        uint256 actualVWAP = vwapTracker.getVWAP();

        assertEq(actualVWAP, expectedVWAP, "VWAP should be correctly calculated across multiple recordings");
        assertEq(vwapTracker.cumulativeVolume(), totalVolume, "Total volume should be sum of all volumes");
    }

    // ========================================
    // EDGE CASE TESTS
    // ========================================

    function testZeroVolumeHandling() public {
        // Don't record any prices
        assertEq(vwapTracker.getVWAP(), 0, "VWAP should be zero with no volume");
        assertEq(vwapTracker.getAdjustedVWAP(CAPITAL_INEFFICIENCY), 0, "Adjusted VWAP should be zero with no volume");
    }

    function testMinimalValues() public {
        // Test with minimal non-zero values
        vwapTracker.recordVolumeAndPrice(1, 1);

        uint256 expectedVolume = 100; // 1 * 100
        uint256 expectedVWAP = 1;

        assertEq(vwapTracker.cumulativeVolume(), expectedVolume, "Volume should handle minimal values");
        assertEq(vwapTracker.getVWAP(), expectedVWAP, "VWAP should handle minimal values");
    }

    function testLargeButSafeValues() public {
        // Test with large but safe values (below overflow threshold)
        uint256 largePrice = type(uint128).max;
        uint256 largeFee = type(uint64).max;

        vwapTracker.recordVolumeAndPrice(largePrice, largeFee);

        uint256 expectedVolume = largeFee * 100;
        uint256 expectedVWAP = largePrice;

        assertEq(vwapTracker.cumulativeVolume(), expectedVolume, "Volume should handle large values");
        assertEq(vwapTracker.getVWAP(), expectedVWAP, "VWAP should handle large values");
    }
}