如何对Chainlink的可验证随机函数进行本地单元测试？

npm install truffle @chainlink/contracts

const { expect } = require('chai');
const { ethers } = require('hardhat');
const { VRFConsumerBase } = require('@chainlink/contracts/src/v0.8/VRFConsumerBase.sol');

describe('VRF Consumer', function () {
  let vrfConsumer;
  let vrfCoordinator;
  let linkToken;
  let owner;

  beforeEach(async function () {
    [owner] = await ethers.getSigners();
    const VRFConsumer = await ethers.getContractFactory('VRFConsumer');
    vrfConsumer = await VRFConsumer.deploy();
    const VRFCoordinator = await ethers.getContractFactory('VRFCoordinatorMock');
    vrfCoordinator = await VRFCoordinator.deploy();
    const LinkToken = await ethers.getContractFactory('LinkToken');
    linkToken = await LinkToken.deploy();

    // 设置依赖关系
    await vrfConsumer.setVRFCoordinator(vrfCoordinator.address);
    await vrfConsumer.setLinkToken(linkToken.address);
  });

  it('should generate and verify a random number', async function () {
    const requestId = ethers.utils.keccak256(ethers.utils.toUtf8Bytes('testRequest'));
    const payment = ethers.utils.parseEther('1');

    // 转移LINK代币
    await linkToken.transfer(vrfConsumer.address, payment);
    await vrfConsumer.fundAndRequestRandomness(requestId, payment);

    // 模拟VRF协调器响应
    const randomness = ethers.utils.hexlify(ethers.utils.randomBytes(32));
    await vrfCoordinator.fulfillRandomness(requestId, randomness);

    // 验证结果
    const result = await vrfConsumer.getRandomNumber(requestId);
    expect(result).to.equal(randomness);
  });
});