如何在本地对 Chainlink 的可验证随机函数进行单元测试？

Question

上下文

在尝试设置用于测试 this Chainlink VRF random number contract 的基本自托管单元测试环境（和 CI）时，我在如何在本地模拟任何相关区块链/测试网时遇到了一些困难。

例如，我找到了this repository that tests Chainlinks VRF。但是，对于默认部署，它建议/需要免费的KOVAN_RPC_URL，例如来自 Infura 的网站，甚至对于“本地部署”，它建议/需要来自例如的免费 MAINNET_RPC_URL Alchemy 的网站。

尝试/基线

我采用了来自 waffle 框架的单元测试环境，描述为：

文件结构

src____AmIRichAlready.sol
   |____RandomNumberConsumer.sol
   |
test____AmIRichAlready.test.ts
   |____mocha.opts
package.json
tsconfig.json
waffle.json
yarn.lock

文件内容

AmIRichAlready.sol

pragma solidity ^0.6.2;

interface IERC20 {
    function balanceOf(address account) external view returns (uint256);
}

contract AmIRichAlready {
    IERC20 private tokenContract;
    uint public richness = 1000000 * 10 ** 18;

    constructor (IERC20 _tokenContract) public {
        tokenContract = _tokenContract;
    }

    function check() public view returns (bool) {
        uint balance = tokenContract.balanceOf(msg.sender);
        return balance > richness;
    }

    // IS THIS NEEDED???
    function setRichness(uint256 _richness) public {
      richness = _richness;
    }
}

RandomNumberConsumer.sol 文件内容已在 stackexange over here 上。

AmIRichAlready.test.ts

import {expect, use} from 'chai';
import {Contract, utils, Wallet} from 'ethers';
import {deployContract, deployMockContract, MockProvider, solidity} from 'ethereum-waffle';

import IERC20 from '../build/IERC20.json';
import AmIRichAlready from '../build/AmIRichAlready.json';

use(solidity);

describe('Am I Rich Already', () => {
  let mockERC20: Contract;
  let contract: Contract;
  let vrfContract: Contract;
  let wallet: Wallet;

  beforeEach(async () => {
    [wallet] = new MockProvider().getWallets();
    mockERC20 = await deployMockContract(wallet, IERC20.abi);
    contract = await deployContract(wallet, AmIRichAlready, [mockERC20.address]);
    vrfContract = await deployContract(wallet, RandomNumberConsumer);
  });

  it('checks if contract called balanceOf with certain wallet on the ERC20 token', async () => {
    await mockERC20.mock.balanceOf
      .withArgs(wallet.address)
      .returns(utils.parseEther('999999'));
    await contract.check();
    expect('balanceOf').to.be.calledOnContractWith(mockERC20, [wallet.address]);
  });

  it('returns false if the wallet has less than 1000000 coins', async () => {
    await mockERC20.mock.balanceOf
      .withArgs(wallet.address)
      .returns(utils.parseEther('999999'));
    expect(await contract.check()).to.be.equal(false);
  });

  it('returns true if the wallet has at least 1000000 coins', async () => {
    await mockERC20.mock.balanceOf
      .withArgs(wallet.address)
      .returns(utils.parseEther('1000000'));
    expect(await contract.check()).to.be.equal(false);
  });
});

mocha.opts

-r ts-node/register/transpile-only
--timeout 50000
--no-warnings
test/**/*.test.{js,ts}

package.json

{
  "name": "example-dynamic-mocking-and-testing-calls",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "scripts": {
    "test": "export NODE_ENV=test && mocha",
    "build": "waffle",
    "lint": "eslint '{src,test}/**/*.ts'",
    "lint:fix": "eslint --fix '{src,test}/**/*.ts'"
  },
  "devDependencies": {
    "@openzeppelin/contracts": "^4.3.1",
    "@types/chai": "^4.2.3",
    "@types/mocha": "^5.2.7",
    "@typescript-eslint/eslint-plugin": "^2.30.0",
    "@typescript-eslint/parser": "^2.30.0",
    "chai": "^4.3.4",
    "eslint": "^6.8.0",
    "eslint-plugin-import": "^2.20.2",
    "ethereum-waffle": "^3.4.0",
    "ethers": "^5.0.17",
    "mocha": "^7.2.0",
    "ts-node": "^8.9.1",
    "typescript": "^3.8.3"
  }
}

tsconfig.json

{
  "compilerOptions": {
    "declaration": true,
    "esModuleInterop": true,
    "lib": [
      "ES2018"
    ],
    "module": "CommonJS",
    "moduleResolution": "node",
    "outDir": "dist",
    "resolveJsonModule": true,
    "skipLibCheck": true,
    "strict": true,
    "target": "ES2018"
  }

  // custom test in vrfContract
  it('Tests if a random number is returned', async () => {
    expect(await vrfContract.getRandomNumber()).to.be.equal(7);
  });
}

waffle.json

{
  "compilerType": "solcjs",
  "compilerVersion": "0.6.2",
  "sourceDirectory": "./src",
  "outputDirectory": "./build"
}

yarn.lock 文件内容有点大，而且是自动生成的，所以你可以找到它on the Waffle framework repository。同样，package.json 可以在同一存储库中找到 here。

命令

也可以简单地克隆具有指定文件结构here 的 repo，并使用以下命令运行测试：

git clone git@github.com:a-t-2/chainlink.git
git clone git@github.com:a-t-2/test_vrf3.git
cd test_vrf3
sudo apt install npm
npm install
npm audit fix
npm install --save-dev ethereum-waffle
npm install @openzeppelin/contracts -D
npm i chai -D
npm i mocha -D
rm -r build
npx waffle
npx mocha
npm test

测试输出

这将测试AmIRichAlready.sol 文件并输出：

  Am I Rich Already
    ✓ checks if contract called balanceOf with certain wallet on the ERC20 token (249ms)
    ✓ returns false if the wallet has less than 1000000 coins (190ms)
    ✓ returns true if the wallet has at least 1000000 coins (159ms)
    Tests if a random number is returned:
     Error: cannot estimate gas; transaction may fail or may require manual gas limit (error={"name":"RuntimeError","results":{"0x0a0b028de6cf6e8446853a300061305501136cefa5f5eb3e96afd95dbd73dd92":{"error":"revert","program_counter":609,"return":"0x"}},"hashes":["0x0a0b028de6cf6e8446853a300061305501136cefa5f5eb3e96afd95dbd73dd92"],"message":"VM Exception while processing transaction: revert"}, tx={"data":"0xdbdff2c1","to":{},"from":"0x17ec8597ff92C3F44523bDc65BF0f1bE632917ff","gasPrice":{"type":"BigNumber","hex":"0x77359400"},"type":0,"nonce":{},"gasLimit":{},"chainId":{}}, code=UNPREDICTABLE_GAS_LIMIT, version=abstract-signer/5.4.1)
      at Logger.makeError (node_modules/@ethersproject/logger/src.ts/index.ts:225:28)
      at Logger.throwError (node_modules/@ethersproject/logger/src.ts/index.ts:237:20)
      at /home/name/git/trucol/tested/new_test/test_vrf3/node_modules/@ethersproject/abstract-signer/src.ts/index.ts:301:31
      at process._tickCallback (internal/process/next_tick.js:68:7)



  3 passing (4s)

问题

如果提供了足够的“gas”，我需要哪些文件、文件结构和命令来自动测试getRandomNumber() 合约是否返回整数，否则返回错误？

Answer 1

我也遇到过这个问题，通过 mocking 解决了。这是我的 MockVRFCoordinator：

//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@chainlink/contracts/src/v0.8/VRFConsumerBaseV2.sol";

contract MockVRFCoordinator {
    uint256 internal counter = 0;

    function requestRandomWords(
        bytes32,
        uint64,
        uint16,
        uint32,
        uint32
    ) external returns (uint256 requestId) {
        VRFConsumerBaseV2 consumer = VRFConsumerBaseV2(msg.sender);
        uint256[] memory randomWords = new uint256[](1);
        randomWords[0] = counter;
        consumer.rawFulfillRandomWords(requestId, randomWords);
        counter += 1;
    }
}

您可以在我的repository 中查看测试示例

Answer 2

要在本地进行测试，您需要使用mocks，它可以模拟拥有一个预言机网络。因为您在本地工作，所以 Chainlink 节点不知道您的本地区块链，因此您实际上无法执行正确的 VRF 请求。请注意，您可以尝试部署本地 Chainlink 节点和本地区块链并让它们交谈，但它还没有完全支持，因此您可能会得到不同的结果。无论如何，根据您链接的hardhat starter kit，您可以在 hardhat.config.js 文件中将 defaultNetwork 设置为“hardhat”，然后在部署和运行集成测试（yarn test-integration）时，它将使用mocks 模拟 VRF 节点，并测试随机数的请求。查看测试here，模拟合约和链接令牌被部署here