brownie：ValueError: execution reverted: VM Exception while processing transaction: revert

Macbook Pro : Monterey

Intel Core i7

Brownie v1.17.2

I am learning solidity according to reference(https://www.youtube.com/watch?v=M576WGiDBdQ&t=25510s).

What I tried to do here, is use brownie to deploy a contract(FundMe) in a script (deploy.py),then write a test script(scripts/fund_and_withdraw.py.py)

I met the same error,the MockV3Aggregator deployed successfully, but the getEntrancePrice is 0 Googled it find this answer,don't quite follow.(https://ethereum.stackexchange.com/questions/114889/deploying-ganache-local-w-brownie-vm-exception-while-processing-transaction-in)

getPrice() isn't returning a number you want from the mock, somewhere in the vicinity of 2B. Think this is a bug with the Ganache implementation- performing the calculation (minimumUSD * precision) / price in getEntranceFee() gives you a number less than 1- and, since Solidity can't handle floats, Solidity simply sees it as a 0, and the whole thing errors out.

scripts/fund_and_withdraw.py

from brownie import FundMe
from scripts.helpful_scripts import get_account





def fund():
    fund_me = FundMe[-1]

    account = get_account()

    entrance_fee = fund_me.getEntranceFee()
    print(f"The entrance fee is : {entrance_fee} !")
    print("funding")
    fund_me.fund({"from": account, "value": entrance_fee})
    print(f"Funded {entrance_fee} !")


def withdraw():
    fund_me = FundMe[-1]
    account = get_account()
    fund_me.withdraw({"from": account})


def main():
    fund()
    withdraw()

deploy.py

from brownie import FundMe, network, config, MockV3Aggregator
from scripts.helpful_scripts import (
    get_account,
    deploy_mocks,
    LOCAL_BLOCKCHAIN_ENVIRONMENT,
)


def deploy_fund_me():
    account = get_account()
    # if we have a persistent network like rinkeby,use the associated address
    # otherwise ,deploy mocks
    if network.show_active() not in LOCAL_BLOCKCHAIN_ENVIRONMENT:
        price_feed_address = config["networks"][network.show_active()][
            "eth_usd_price_feed"
        ]
    else:
        deploy_mocks()
        # just use the latest mockV3Aggregator
        price_feed_address = MockV3Aggregator[-1].address
        print("***********************************************************")
        print(f"MockVeAggrator's address is {price_feed_address}")

    fund_me = FundMe.deploy(
        price_feed_address,
        {"from": account},
        publish_source=config["networks"][network.show_active()].get("verify"),
    )
    print("***********************************************************")
    print(f"The Ether price is :{fund_me.getPrice()}\n")
    print(f"Contract deployed to {fund_me.address}\n")
    entrance_fee = fund_me.getEntranceFee()
    print("***********************************************************")
    print(f"The entrance fee is : {entrance_fee} !\n")
    return fund_me


def main():
    deploy_fund_me()

FundMe.sol

// SPDX-License-Identifier: MIT

pragma solidity 0.8.0;

// we need tell brownie @chainlink means == what input in config,need to tell compiler

import "@chainlink/contracts/src/v0.6/interfaces/AggregatorV3Interface.sol";

import "@chainlink/contracts/src/v0.6/vendor/SafeMathChainlink.sol";

contract FundMe {
    //using SafeMathChainlink for uint256;

    mapping(address => uint256) public addressToAmountFunded;
    address[] public funders;
    address public owner;
    AggregatorV3Interface public priceFeed;

    // if you're following along with the freecodecamp video
    // Please see https://github.com/PatrickAlphaC/fund_me
    // to get the starting solidity contract code, it'll be slightly different than this!
    constructor(address _priceFeed) {
        // make price feed a parameter
        priceFeed = AggregatorV3Interface(_priceFeed);
        owner = msg.sender;
    }

    function fund() public payable {
        uint256 mimimumUSD = 50 * 10**18;
        require(
            getConversionRate(msg.value) >= mimimumUSD,
            "You need to spend more ETH!"
        );
        addressToAmountFunded[msg.sender] += msg.value;
        funders.push(msg.sender);
    }

    function getVersion() public view returns (uint256) {
        return priceFeed.version();
    }

    function getPrice() public view returns (uint256) {
        (, int256 answer, , , ) = priceFeed.latestRoundData();
        return uint256(answer * 10000000000);
    }

    // 1000000000
    function getConversionRate(uint256 ethAmount)
        public
        view
        returns (uint256)
    {
        uint256 ethPrice = getPrice();
        uint256 ethAmountInUsd = (ethPrice * ethAmount) / 1000000000000000000;
        return ethAmountInUsd;
    }

    function getEntranceFee() public view returns (uint256) {
        // mimimumUSD
        uint256 mimimumUSD = 50 * 10**18;
        uint256 price = getPrice();
        uint256 precision = 1 * 10**18;
        return (mimimumUSD * precision) / price;
    }

    modifier onlyOwner() {
        require(msg.sender == owner);
        _;
    }

    function withdraw() public payable onlyOwner {
        payable(msg.sender).transfer(address(this).balance);

        for (
            uint256 funderIndex = 0;
            funderIndex < funders.length;
            funderIndex++
        ) {
            address funder = funders[funderIndex];
            addressToAmountFunded[funder] = 0;
        }
        funders = new address[](0);
    }
}

update the error disappear magicly (may be come back later),right now the error info is :list out of index actually i faced the same error in another project (Brownie test IndexError: list index out of range)

according the answer and brownie docs, I need to add account. what confused me is if I launched the ganache local blockchain already ,why I still need to add account or I added the wrong way?

Solution 1:

function getEntranceFee() public view returns (uint256) {
        // mimimumUSD
        uint256 mimimumUSD = 50 * 10**18;
        uint256 price = getPrice();
        uint256 precision = 1 * 10**18;
        return (mimimumUSD * precision) / price;
    }

You do not need to multiply with precison. currently, assuming eth price 3000, you are returning

 (50 * (10^18) * (10^18)) / (3000 * 10^10)

 (50 * (10^36)) / (3 * 10^13)

 (50/3)*(10^23)

I think your return value should be

  return mimimumUSD  / price;