详解如何把ERC20代币迁移到新合约（升级）

创建运行环境

1. 首先要初始化环境

$ npm init -y   //初始化npm环境
$ npm install truffle -g //安装truffle过就请跳过
$ truffle init  //初始化truffle环境
$ npm install @openzeppelin/contracts@2.5.0 //安装openzeppelin合约
$ npm install --save-dev @openzeppelin/test-helpers //安装openzeppelin测试助手
$ npm install --save-dev @openzeppelin/test-environment mocha chai  //安装openzeppelin //测试环境
$ npm install @truffle/debug-utils 

2. 修改package.json

$ vim package.json

// package.json

"scripts": {
  "test": "mocha --exit --recursive",
  "compile": "truffle compile",
  "ganache": "ganache-cli -e 1000",
  "migrate":"truffle migrate"
}

布署一个ERC20合约作为旧合约

1. 新建一个ERC20合约

$ vim contracts/ERC20LegacyToken.sol

合约内容:

pragma solidity >=0.4.21 <0.7.0;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20Detailed.sol";

contract ERC20LegacyToken is ERC20, ERC20Detailed {
    constructor(
        string memory name,   //代币名称
        string memory symbol, //代币缩写
        uint8 decimals,       //精度
        uint256 totalSupply   //发行总量
    ) public ERC20Detailed(name, symbol, decimals) {
        _mint(msg.sender, totalSupply * (10**uint256(decimals)));
    }
}

2. 编译合约

$ npm run compile

3.布署脚本

$ vim migrations/2_deploy_ERC20LegacyToken.js

const ERC20LegacyToken = artifacts.require("ERC20LegacyToken"); 
module.exports = function(deployer) {
    deployer.deploy(ERC20LegacyToken,
    "My Golden Coin","MGC",18,1000000000);
};

4. 布署合约

$ npm run ganache //创建一个测试节点
$ npm run migrate //在另一个窗口运行

创建并布署迁移合约

1. 创建迁移合约

$ vim contracts/ERC20Migrator.sol

pragma solidity ^0.5.0;
import "@openzeppelin/contracts/drafts/ERC20Migrator.sol";

//代币迁移合约
contract ERC20MigratorContract is ERC20Migrator {
    constructor(
        IERC20 legacyToken    //旧代币合约
    )
        ERC20Migrator(legacyToken)
        public
    {

    }
}

2. 编译合约

$ npm run compile

3. 布署脚本

$ vim migrations/3_deploy_ERC20Migrator.js

const ERC20MigratorContract = artifacts.require("ERC20MigratorContract"); 
const ERC20LegacyToken = artifacts.require("ERC20LegacyToken"); 
module.exports = async function(deployer) {
    const ERC20LegacyTokenInstance = await ERC20LegacyToken.deployed();
    deployer.deploy(
    ERC20MigratorContract,
        ERC20LegacyTokenInstance.address
    );
};

4. 布署合约

$ npm run migrate //请确保ganache测试节点还在运行

布署新的ERC20合约

1. 新建一个可增发的ERC20合约

$ vim contracts/ERC20NewToken.sol

合约内容:

pragma solidity >=0.4.21 <0.7.0;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20Detailed.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20Mintable.sol";

contract ERC20NewToken is ERC20, ERC20Detailed, ERC20Mintable {
    constructor(
        string memory name, //代币名称
        string memory symbol, //代币缩写
        uint8 decimals, //精度
        uint256 totalSupply //发行总量
    ) public ERC20Detailed(name, symbol, decimals) {
        _mint(msg.sender, totalSupply * (10**uint256(decimals)));
    }
}

2. 编译合约

$ npm run compile

3.布署脚本

$ vim migrations/4_deploy_ERC20NewToken.js

const ERC20NewToken = artifacts.require("ERC20NewToken"); 
module.exports = function(deployer) {
    deployer.deploy(ERC20NewToken,
    "My Golden Coin","MGC",18,0);//初始发行量为0
};

4. 布署合约

$ npm run migrate //请确保ganache测试节点还在运行

通过测试脚本来模拟运行

1.创建测试脚本

$ vim test/ERC20Migrator.js

const assert = require('assert');
const { contract, accounts, web3 } = require('@openzeppelin/test-environment');
const { ether, time, expectEvent } = require('@openzeppelin/test-helpers');
const ERC20LegacyToken = contract.fromArtifact("ERC20LegacyToken");
const ERC20Migrator = contract.fromArtifact("ERC20MigratorContract");
const ERC20NewToken = contract.fromArtifact("ERC20NewToken");

const totalSupply = '1000000000';//发行总量
[owner, sender, receiver, purchaser, beneficiary] = accounts;
EthValue = '100';
let balanceBefore = [];

//批准和迁移方法
migrateBalance = async (account) => {
    await ERC20Instance.approve(ERC20MigratorInstance.address, balanceBefore[account], { from: account });
    await ERC20MigratorInstance.migrate(account, balanceBefore[account]);
}
//验证余额方法
assertBalanceAfter = async (account) => {
    let balanceAfter = await ERC20NewTokenInstance.balanceOf(account);
    assert.equal(balanceBefore[account].toString(), balanceAfter.toString());
}
//传送方法
transfer = async (sender, receiver, amount) => {
    let receipt = await ERC20Instance.transfer(receiver, ether(amount), { from: sender });
    expectEvent(receipt, 'Transfer', {
        from: sender,
        to: receiver,
        value: ether(amount),
    });
}

describe("布署合约", function () {
    it('布署旧代币合约', async function () {
        ERC20Param = [
            "My Golden Coin",   //代币名称
            "MGC",              //代币缩写
            18,                 //精度
            totalSupply         //发行总量
        ];
        ERC20Instance = await ERC20LegacyToken.new(...ERC20Param, { from: owner });
    });
    it('布署代币迁移合约', async function () {
        ERC20MigratorInstance = await ERC20Migrator.new(
            ERC20Instance.address,        //旧代币合约地址
            { from: owner });
    });
    it('布署新代币合约', async function () {
        ERC20NewTokenParam = [
            "My Golden Coin",   //代币名称
            "MGC",              //代币缩写
            18,                 //精度
            0                   //发行总量
        ];
        ERC20NewTokenInstance = await ERC20NewToken.new(...ERC20NewTokenParam, { from: owner });
    });
});
describe("布署后首先执行", function () {
    it('将代币批准给众筹合约', async function () {
        await ERC20Instance.approve(ERC20MigratorInstance.address, ether(totalSupply.toString()), { from: owner });
    });
    it('添加众筹合约的铸造权: addMinter()', async function () {
        await ERC20NewTokenInstance.addMinter(ERC20MigratorInstance.address, { from: owner });
    });
    it('撤销发送者的铸造权: renounceMinter()', async function () {
        let receipt = await ERC20NewTokenInstance.renounceMinter({ from: owner });
        expectEvent(receipt, 'MinterRemoved', {
            account: owner
        });
    });
});
describe("迁移合约基本信息", function () {
    it('旧合约地址: legacyToken()', async function () {
        assert.equal(ERC20Instance.address, await ERC20MigratorInstance.legacyToken());
    });
});
describe("将旧合约代币分配给一些账户", function () {
    it('代币分配: transfer()', async function () {
        //代币发送给sender
        await transfer(owner, sender, (EthValue * 5).toString());
        //代币发送给receiver
        await transfer(owner, receiver, (EthValue * 10).toString());
        //代币发送给purchaser
        await transfer(owner, purchaser, (EthValue * 15).toString());
        //代币发送给beneficiary
        await transfer(owner, beneficiary, (EthValue * 25).toString());
    });
    it('记录账户旧合约余额: balanceOf()', async function () {
        balanceBefore[owner] = await ERC20Instance.balanceOf(owner);
        balanceBefore[sender] = await ERC20Instance.balanceOf(sender);
        balanceBefore[receiver] = await ERC20Instance.balanceOf(receiver);
        balanceBefore[purchaser] = await ERC20Instance.balanceOf(purchaser);
        balanceBefore[beneficiary] = await ERC20Instance.balanceOf(beneficiary);
    });
});
describe("开始迁移", function () {
    it('开始迁移: beginMigration()', async function () {
        await ERC20MigratorInstance.beginMigration(ERC20NewTokenInstance.address, { from: owner });
    });
    it('验证新约地址: newToken()', async function () {
        assert.equal(ERC20NewTokenInstance.address, await ERC20MigratorInstance.newToken());
    });
    it('迁移owner账户全部余额方法: migrateAll()', async function () {
        await ERC20MigratorInstance.migrateAll(owner);
    });
    it('迁移指定账户余额方法: migrate()', async function () {
        await migrateBalance(sender);
        await migrateBalance(receiver);
        await migrateBalance(purchaser);
        await migrateBalance(beneficiary);
    });
});
describe("验证余额", function () {
    it('验证账户迁移后新合约余额: balanceOf()', async function () {
        await assertBalanceAfter(owner);
        await assertBalanceAfter(sender);
        await assertBalanceAfter(receiver);
        await assertBalanceAfter(purchaser);
        await assertBalanceAfter(beneficiary);
    });
    it('验证账旧ERC20合约余额: balanceOf()', async function () {
        assert.equal('0', (await ERC20Instance.balanceOf(owner)).toString());
        assert.equal('0', (await ERC20Instance.balanceOf(sender)).toString());
        assert.equal('0', (await ERC20Instance.balanceOf(receiver)).toString());
        assert.equal('0', (await ERC20Instance.balanceOf(owner)).toString());
        assert.equal('0', (await ERC20Instance.balanceOf(beneficiary)).toString());
    });
});

2. 运行测试

$ npm run test

3. 运行结果

> truffle@1.0.0 test /home/Documents/truffle
> mocha --exit --recursive

  布署合约
    ✓ 布署旧代币合约 (404ms)
    ✓ 布署代币迁移合约 (47ms)
    ✓ 布署新代币合约 (91ms)

  布署后首先执行
    ✓ 将代币批准给众筹合约 (47ms)
    ✓ 添加众筹合约的铸造权: addMinter()
    ✓ 撤销发送者的铸造权: renounceMinter()

  迁移合约基本信息
    ✓ 旧合约地址: legacyToken()

  将旧合约代币分配给一些账户
    ✓ 代币分配: transfer() (134ms)
    ✓ 记录账户旧合约余额: balanceOf() (92ms)

  开始迁移
    ✓ 开始迁移: beginMigration()
    ✓ 验证新约地址: newToken()
    ✓ 迁移owner账户全部余额方法: migrateAll() (64ms)
    ✓ 迁移指定账户余额方法: migrate() (314ms)

  验证余额
    ✓ 验证账户迁移后新合约余额: balanceOf() (86ms)
    ✓ 验证账旧ERC20合约余额: balanceOf() (82ms)

  15 passing (2s)

在上面这个测试中,我们模拟了一个从旧ERC20代币合约迁移到新合约的全过程. 创建者首先转移了一些数量的代币给了几个用户.随后运行可迁移合约,开始迁移时指定了新合约的地址.当迁移合约布署好之后,持有旧合约代币的用户将余额批准给了迁移合约,然后从迁移合约中运行迁移方法.迁移合约先将旧合约中的批准的代币都转移到自己的账户上.然后再触发新合约中的铸币方法,在新合约中为迁移到用户生成了新的代币.

更多发行ERC20代币的方法请关注我的Github