feat: Add BalanceDropTrap example with working config and tests

[hyapiskan]

No description provided.

[hyapiskan]

Hello Drosera Team,

Thanks for the review! Here are the contents of the files for the Proof-of-Concept trap as requested:

---

foundry/balance-drop-trap/src/BalanceDropTrap.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import {ITrap} from "drosera-contracts/interfaces/ITrap.sol";

// This trap detects sudden drops in the ETH balance of a specific wallet.
contract BalanceDropTrap is ITrap {
    // The wallet address to monitor (Example: Vitalik Buterin's address)
    address constant TARGET_WALLET = 0xAb5801a7D398351b8bE11C439e05C5B3259aeC9B;
    // The threshold percentage for the alert (e.g., if it drops by more than 50%)
    uint256 constant THRESHOLD_PERCENT = 50;

    // This function runs on every block and records the wallet's current ETH balance.
    function collect() external view returns (bytes memory) {
        return abi.encode(TARGET_WALLET.balance);
    }

    // This function analyzes the data from past blocks.
    function shouldRespond(bytes[] calldata data) external pure returns (bool, bytes memory) {
        // At least 2 blocks of data are needed for analysis (previous and current balance).
        if (data.length < 2) {
            return (false, bytes(""));
        }

        uint256 previousBalance = abi.decode(data[data.length - 2], (uint256));
        uint256 currentBalance = abi.decode(data[data.length - 1], (uint256));

        // If the balance has not dropped or the previous balance was 0, there is no issue.
        if (currentBalance >= previousBalance || previousBalance == 0) {
            return (false, bytes(""));
        }

        // Calculate the drop amount and percentage.
        uint256 dropAmount = previousBalance - currentBalance;
        uint256 dropPercentage = (dropAmount * 100) / previousBalance;

        // If the drop percentage is greater than our threshold, TRIGGER THE ALARM!
        if (dropPercentage >= THRESHOLD_PERCENT) {
            return (true, abi.encode(previousBalance, currentBalance));
        }

        // If the drop is less than the threshold, there is no issue.
        return (false, bytes(""));
    }
}

foundry/balance-drop-trap/test/BalanceDropTrap.t.sol


// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import {Test} from "forge-std/Test.sol";
import {BalanceDropTrap} from "../../src/BalanceDropTrap.sol";

// Our test contract inherits from Foundry's Test contract.
contract BalanceDropTrapTest is Test {
    BalanceDropTrap public trap;

    // This function runs before each test and deploys our trap.
    function setUp() public {
        trap = new BalanceDropTrap();
    }

    // This test verifies that the trap should respond on a significant drop.
    function testShouldRespondOnSignificantDrop() public {
        // We simulate historical data.
        bytes[] memory data = new bytes[](2);
        
        // Previous balance: 100 ETH
        data = abi.encode(100 ether);
        // Current balance: 40 ETH (a 60% drop)
        data = abi.encode(40 ether);

        // We call our trap's shouldRespond function with this mock data.
        (bool should, ) = trap.shouldRespond(data);

        // We expect the result to be 'true' and assert this.
        assertTrue(should, "Trap should respond on a >50% balance drop");
    }

    // This test verifies that the trap should NOT respond on an insignificant drop.
    function testShouldNotRespondOnInsignificantDrop() public {
        // We simulate historical data.
        bytes[] memory data = new bytes[](2);
        
        // Previous balance: 100 ETH
        data = abi.encode(100 ether);
        // Current balance: 80 ETH (a 20% drop)
        data = abi.encode(80 ether);

        (bool should, ) = trap.shouldRespond(data);

        // We expect the result to be 'false' and assert this.
        assertFalse(should, "Trap should NOT respond on a <50% balance drop");
    }
}



foundry/balance-drop-trap/foundry.toml



[profile.default]
src = 'src'
test = 'test'
libs = ['../../node_modules']
remappings = [
    'drosera-contracts/=../../node_modules/contracts/src/',
    'forge-std/=../../node_modules/forge-std/src/'
]