Mocha 测试验证 solidity 合约余额

Question

我有这样的 solidity 合同：

pragma solidity ^0.4.17;

contract Lottery {

    address public manager;

    address[] public players;

    function Lottery() public {
        manager = msg.sender;
    }

    function enter() public payable {
        require(msg.value > .01 ether);
        players.push(msg.sender);
    }

    function random() private view returns (uint) {
        return uint(keccak256(block.difficulty, now, players));
    }

    function pickWinner() public restricted {
        uint index = random() % players.length;
        players[index].transfer(this.balance);
        players = new address[](0);
    }

    modifier restricted() {
        require(msg.sender == manager);
        _;
    }

    function getPlayers() public view returns (address[]) {
        return players;
    }

    function getBalance() public view returns (uint) {
      return this.balance;
    }

}

我正在尝试测试在选择获胜者后 balance/pot 是否恢复为零。这是我的测试文件中的 it 语句：

  it('sends money to the winner and resets the players array', async() => {
    await lottery.methods.enter().send({
      from: accounts[0],
      value: web3.utils.toWei('2', 'ether')
    });

    const initialBalance = await web3.eth.getBalance(accounts[0]);
    await lottery.methods.pickWinner().send({ from: accounts[0] });
    const finalBalance = await web3.eth.getBalance(accounts[0]);
    const difference = finalBalance - initialBalance;
    const players = await lottery.methods.getPlayers().call({
          from: accounts[0]
    });
    const pot = await lottery.methods.getBalance();

    assert(difference > web3.utils.toWei('1.8', 'ether'));
    assert.equal(0, players.length);
    assert.equal(0, pot);
  });

当我将智能合约部署到 remix - ethereum IDE getBalance returns 想要的余额但是当我运行 npm 运行在本地测试然后我得到一个断言错误：

AssertionError [ERR_ASSERTION]: 0 == {
  _ethAccounts: <ref *7> Accounts {
    _ethereumCall: {
      getChainId: [Function: send] {
        call: 'eth_chainId',
        method: Method {
          abiCoder: undefined,
          accounts: undefined,
          call: 'eth_chainId',
          defaultAccount: null,
          defaultBlock: 'latest',
          defaultChain: undefined,
          defaultCommon: undefined,
          defaultHardfork: undefined,
          extraFormatters: undefined,
          handleRevert: undefined,
          inputFor...
      at Context.<anonymous> (test/Lottery.test.js:101:12)
      at processTicksAndRejections (node:internal/process/task_queues:96:5)

我该如何解决这个问题？ p.s。这个合约是为了学习目的我知道随机性不是很稳健

Answer 1

当您使用web3js调用合约只读方法时，您需要使用.call()函数。

const pot = await lottery.methods.getBalance().call()`; // added `.call()`

而不是

const pot = await lottery.methods.getBalance(); // original code

文档：https://web3js.readthedocs.io/en/v1.4.0/web3-eth-contract.html#methods-mymethod-call

Answer 2

如果您的目的只是为了测试余额，请使用 web3.eth.getBalance 而不是在合约中定义 getBalance。

const contractBalance = await web3.eth.getBalance(lottery.options.address);

Mocha 测试验证 solidity 合约余额

Mocha test verify solidity contract balance

mocha.js

solidity