function packFixedRewards(uint256[] memory rewards) private view returns (uint256 packed) {
    if (rewards.length != (selectionSize) || rewards[0] != 0) {
        revert InvalidFixedRewardSetup();
    }
    uint256 divisor = 10 ** (IERC20Metadata(address(rewardToken)).decimals() - 1);
    for (uint8 winTier = 1; winTier < selectionSize; ++winTier) {
        uint16 reward = uint16(rewards[winTier] / divisor);
        if ((rewards[winTier] % divisor) != 0) {
            revert InvalidFixedRewardSetup();
        }
        packed |= uint256(reward) << (winTier * 16);
    }
}
uint16 reward = uint16(rewards[winTier] / divisor);
(tokenAmount * 10) & type(uint16).max = (7000 * 10) & (2 ** 16 - 1) = 4464
4464 / 10 = 446
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.13;

import "forge-std/Test.sol";
import "../src/LotterySetup.sol";
import "./TestToken.sol";

contract RewardUnsafeCastTest is Test {
    ERC20 public rewardToken;

    uint8 public constant SELECTION_SIZE = 3;
    uint8 public constant SELECTION_MAX = 10;

    function setUp() public {
        rewardToken = new TestToken();
    }

    function testRewardIsSmallerThanExpected() public {
        // Get 1 token unit
        uint256 tokenUnit = 10 ** rewardToken.decimals();

        // Define fixedRewards as [0, 6500, 7000]
        uint256[] memory fixedRewards = new uint256[](SELECTION_SIZE);
        fixedRewards[1] = 6500 * tokenUnit;
        fixedRewards[2] = 7000 * tokenUnit;

        // Initialize LotterySetup contract
        LotterySetup lotterySetup = new LotterySetup(
            LotterySetupParams(
                rewardToken,
                LotteryDrawSchedule(block.timestamp + 2*100, 100, 60),
                5 ether,
                SELECTION_SIZE,
                SELECTION_MAX,
                38e16,
                fixedRewards
            )
        );

        // Reward for winTier 1 is 6500
        assertEq(lotterySetup.fixedReward(1) / tokenUnit, 6500);

        // Reward for winTier 2 is 446 instead of 7000
        assertEq(lotterySetup.fixedReward(2) / tokenUnit, 446);
    }
}
