如何使用 Chainlink 运行 ETH 到 USD 转换测试？

Question

我有以下 Bank.sol 代码

// SPDX-License-Identifier: MIT
pragma solidity >=0.4.22 <0.9.0;

import "@openzeppelin/contracts-upgradeable/access/AccessControlUpgradeable.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@chainlink/contracts/src/v0.8/interfaces/AggregatorV3Interface.sol";
import "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";
import "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";

contract Bank is Initializable, AccessControlUpgradeable {
    // Code to handle two different roles: Manager and User
    bytes32 public constant MANAGER_ROLE = keccak256("MANAGER_ROLE");
    bytes32 public constant USER_ROLE = keccak256("USER_ROLE");
    mapping(address => uint256) private _balances;


    // Code for initializer
    function initialize() public initializer {

    }

    function deposit() public payable {
        _balances[msg.sender] += msg.value;

    }

    function convertToUSD(address account) public view returns (uint256) {
        uint256 ethAmount = _balances[account];
        int256 price = getLatestPrice();
        uint256 usdAmount = uint256(price) * ethAmount / 1e18;
        return usdAmount;
    }

    function getLatestPrice() public view returns (int256) {
        AggregatorV3Interface priceFeed = AggregatorV3Interface(0xD4a33860578De61DBAbDc8BFdb98FD742fA7028e);
        (, int256 price, , , ) = priceFeed.latestRoundData();
        return price;
    }

    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    function withdraw(uint _amount) public {
        require (_balances[msg.sender] >= _amount, "Insufficient balance");
        _balances[msg.sender] -= _amount;
        (bool sent,) = msg.sender.call{value: _amount}("sent");
        require(sent, "Failed to Complete");
    }
}

我正在尝试使用 Truffle 对其进行测试

const Bank = artifacts.require('Bank.sol')

contract("Bank", async accounts => {
    it("User should be able to deposit funds", async () => {
        const bank = await Bank.new()
        const depositer = accounts[1]
        const amount = web3.utils.toWei('10', 'ether')
        await bank.deposit({from: depositer, value: amount})
        let balance = await bank.balanceOf(depositer)
        balance = parseInt(web3.utils.fromWei(balance, 'ether'))
        assert.equal(balance, 10)
        let usd = await bank.convertToUSD(depositer)
        console.log(usd)
    })
})

测试没有最后两行。但是，我试图让代码以美元打印出来，即用户帐户中的金额。出于某种原因，我在 bank.convertToUSD(depositer)

 上收到 

VM Exception while processing transaction: revert

错误

如果有人能指出我可能做错了什么，那就太好了，因为这是我第一次学习这个。谢谢！