错误:找不到模块“bignumber.js”

Question

我正在尝试测试这个智能契约，但我似乎无法克服这个错误，我使用的是最新的松露套件v5.1.16和web3 v1.2.6。

KTokenSale.test.js

const BigNumber = web3.BigNumber;

require('chai')
  .use(require('chai-bignumber')(BigNumber))
  .should();

  const KToken = artifacts.require('KToken');
  const KTokenCrowdsale = artifacts.require('KTokenCrowdsale');

  contract('KTokenCrowdsale', function([_, wallet, investor1, investor2]) {
    beforeEach(async function () {
        this.name = 'TestToken';
        this.symbol = 'TT';
        this.decimals = 16;

        this.token = await KToken.new(
            this.name,
            this.symbol,
            this.decimals
            );

        this.rate = 850;
        this.wallet = wallet;

        this.crowdsale = await KToken.new(
            this.rate,
            this.wallet,
            this.token.address
            );
    });
  });

  contract('crowdsale', function() {
    it('tracks the rate', async function() {
        const rate = await this.crowdsale.rate();
        rate.should.be.bignumber.equal(this.rate);
    });

    it('tracks the wallet', async function() {
        const wallet = await this.crowdsale.wallet();
        wallet.should.equal(this.wallet);
    });

    it('tracks the token', async function() {
        const token = await this.crowdsale.token();
        token.should.equal(this.token.address);
    });
  });

正在测试的智能合同代码：

pragma solidity ^0.5.11;

import "@openzeppelin/contracts/crowdsale/Crowdsale.sol";
import "@openzeppelin/contracts/crowdsale/validation/CappedCrowdsale.sol";

contract KTokenCrowdsale is Crowdsale, CappedCrowdsale {
    uint256 public investorMinCap = 7000000000000000000;
    uint256 public investorMaxCap = 350000000000000000000;
    mapping(address => uint256) public contributions;

    constructor(
        uint256 _rate,
        address payable _wallet,
        IERC20 _token,
        uint256 _cap
    )
    Crowdsale(_rate, _wallet, _token)
    CappedCrowdsale(_cap) public {}
}

Answer 1

web3.BigNumber on web3.js v0.x，web3.utils.BN on web3.js v1.x。

请注意，bignumber.js处理非整数值，这意味着它可以：

1. 接受非整数输入( Number类型或String类型)
2. 生成非整数结果(通过函数‘div’和‘除以’)

这一点，虽然bn.js不处理非整数值，正如明确指出的那样：

注意:这个库不支持小数。

由于Solidity不支持非整数值，web3.js开发团队最终决定用BigNumber代替BN，而不是截断web3用户传递给web3函数的每个非整数值(从而使用户不知道代码中的潜在错误)。