Michael.W基于Foundry精读Openzeppelin第53期——ERC20PresetFixedSupply.sol

0. 版本

[openzeppelin]：v4.8.3，[forge-std]：v1.5.6

0.1 ERC20PresetFixedSupply.sol

Github: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v4.8.3/contracts/token/ERC20/presets/ERC20PresetFixedSupply.sol

ERC20PresetFixedSupply库是一种带预铸造功能的ERC20实现，即在合约部署时直接将全部流通量都铸造给某一地址且部署后无法增发。该库同时继承了ERC20Burnable库，支持销毁和委托销毁功能。ERC20Burnable库详解参见：https://learnblockchain.cn/article/7038

1. 目标合约

ERC20PresetFixedSupply合约可直接部署。

全部foundry测试合约：

Github: https://github.com/RevelationOfTuring/foundry-openzeppelin-contracts/blob/master/test/token/ERC20/preset/ERC20PresetFixedSupply.t.sol

2. 代码精读

2.1 constructor()

    constructor(
        string memory name,
        string memory symbol,
        uint256 initialSupply,
        address owner
    ) ERC20(name, symbol) {
        // 在合约部署时，将全部的流通量都铸造给owner
        _mint(owner, initialSupply);
    }

foundry代码验证：

contract ERC20PresetFixedSupplyTest is Test {
    uint private _initialSupply = 100;
    address private _owner = address(this);
    ERC20PresetFixedSupply private _testing = new ERC20PresetFixedSupply("test name", "test symbol", _initialSupply, _owner);

    function test_Constructor() external {
        assertEq(_testing.totalSupply(), _initialSupply);
        assertEq(_testing.balanceOf(_owner), _initialSupply);

        // support {burn} && {burnFrom} of ERC20Burnable
        // test {burn}
        uint amountToBurn = 1;
        _testing.burn(amountToBurn);
        assertEq(_testing.totalSupply(), _initialSupply - amountToBurn);
        assertEq(_testing.balanceOf(_owner), _initialSupply - amountToBurn);

        // test {burnFrom}
        address spender = address(1);
        _testing.approve(spender, amountToBurn);
        vm.prank(spender);
        _testing.burnFrom(_owner, amountToBurn);
        assertEq(_testing.totalSupply(), _initialSupply - amountToBurn - amountToBurn);
        assertEq(_testing.balanceOf(_owner), _initialSupply - amountToBurn - amountToBurn);
    }
}

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