白帽试验中如何获得冒充钱包的USDC平衡

Question

我正在编写一份智能合同，在购买NFT时使用USDC (因此USDC从卖方转移到买方)。

我试图测试它在草帽，但我有麻烦时，使用USDC在我的安全帽测试。我分叉了goerli测试网，冒充钱包有它在goerli有USDC。

当我用我的帐户进行NFT购买时，它会出现一个错误"ERC20：“，因此我试图显示USDC余额，以了解问题在哪里，但是当我的帐户中有USDC时，USDC余额将返回0。

我遗漏了什么？

这是我的稳固功能：

     function createMarketSale(uint256 tokenId)
        public
    {
        uint priceUSD = idToMarketItem[tokenId].priceUSD;
        address seller = idToMarketItem[tokenId].seller;

      
        USDc.transfer(seller, priceUSD * 10 ** 6);
      
        _transfer(idToMarketItem[tokenId].owner, msg.sender, tokenId);

        idToMarketItem[tokenId].owner = msg.sender;
        idToMarketItem[tokenId].sold = true;
        _itemsSold.increment();
    }

这是我的安全帽测试：

const USDC_ADDRESS = "0x98339D8C260052B7ad81c28c16C0b98420f2B46a";
const USDC_WHALE = "0x682...";
const ERC20ABI = require('./ERC20.json');

beforeEach(async () => {
    [owner, addr1, addr2] = await ethers.getSigners();

    const ArtworkContract = await ethers.getContractFactory("Artwork");
    artworkcontract = await ArtworkContract.deploy();


    // This should send USDC to addr1 but addr1 is not receiving USDC (or I cannot see it!)
    await impersonateFundErc20(
      USDC_ADDRESS,
      USDC_WHALE,
      addr1,
      "50.0",
      6
    );
  }) 

  describe("MarketPlace", () => {

    it("Should create an NFT", async function () {
      const [owner, addr1, addr2] = await ethers.getSigners();
      const whaleAddress = await ethers.getSigner(USDC_WHALE);
      
      await artworkcontract.deployed();
  
      await owner.sendTransaction({
        to: whaleAddress.address,
        value: ethers.utils.parseEther("1000.0"), // Send more ether to impersonated account
      });

      const USDC = new ethers.Contract(USDC_ADDRESS, ERC20ABI, ethers.provider);
      USDCBalance = await USDC.balanceOf(USDC_WHALE);
      console.log("USDCBalance: " + USDCBalance); // This is returning 0

      await artworkcontract.connect(addr1).createToken("uri1","url1",2)
      const allItems = await artworkcontract.fetchAllItems()
      console.log("allItems:",allItems)
  
      const ETHBalance = await ethers.provider.getBalance(USDC_WHALE);
      console.log("ETHBalance: ",ETHBalance);
  
      await artworkcontract.connect(whaleAddress).createMarketSale(1) // reverts with error ERC20: transfer amount exceeds balance

    });

Answer 1

首先，您必须批准USDC合同上的USDC金额，从发件人钱包的前端。然后，您可以在您的合同上调用这个createMarketSale函数，它将把USDC从发送方转移到您的合同，然后从您的合同转移到卖方。

function createMarketSale(uint256 tokenId) public {
   uint256 priceUSD = idToMarketItem[tokenId].priceUSD;
   address seller = idToMarketItem[tokenId].seller;
   // transfer amount from buyer to contract
   USDc.transferFrom(msg.sender, address(this), priceUSD * 10**6);
   // then send from the contract to seller
   USDc.transfer(seller, priceUSD * 10**6);

   _transfer(idToMarketItem[tokenId].owner, msg.sender, tokenId);

   idToMarketItem[tokenId].owner = msg.sender;
   idToMarketItem[tokenId].sold = true;
   _itemsSold.increment();
}