Receiver
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receive() external payable {
//...
}
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基本作用
让合约地址可以以纯转账的方式接收以太, 直接当向合约地址发送以太的时候, receive函数将被调用
比如:
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// SPDX-License-Identifier: SEE LICENSE IN LICENSE
pragma solidity ^0.8.4;
import "hardhat/console.sol";
contract Callee {
receive() external payable {
console.log(
"[LOG] got some money, from:",
msg.sender,
", value:",
msg.value
);
}
function getBalance() public view returns (uint) {
return address(this).balance;
}
}
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const { expect } = require('chai');
const { ethers } = require('hardhat'); // https://docs.ethers.io/v5/
const { loadFixture } = require("@nomicfoundation/hardhat-network-helpers");
describe('ReceiveEther Contract Test Suits', function () {
// https://hardhat.org/tutorial/testing-contracts#reusing-common-test-setups-with-fixtures
// loadFixture将在第一次运行设置，并在其他测试中快速返回到该状态。
async function deployContractFixture() {
const [owner, addr1] = await ethers.getSigners();
const facotry = await ethers.getContractFactory("Callee");
const contract = await facotry.deploy();
return { contract, owner, addr1 };
}
it("测试1", async function () {
const { contract, owner, addr1 } = await loadFixture(deployContractFixture);
let balance = await contract.getBalance();
expect(balance).to.equal(0);
//send ether to contract
await owner.sendTransaction({
to: contract.address,
value: ethers.utils.parseEther("0.01"),
gasLimit: 50000
});
balance = await contract.getBalance();
expect(balance).to.equal(ethers.utils.parseEther("0.01"));
});
});
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输出:
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❯ npx hardhat test ./test/receive.test.js
Compiled 1 Solidity file successfully
ReceiveEther Contract Test Suits
[LOG] got some money, from: 0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266 , value: 10000000000000000
✔ 测试1 (1044ms)
1 passing (1s)
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如果没有receive函数 (或其替代品, 见下面的fallback的附加作用), 则执行会报错
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1) ReceiveEther Contract Test Suits
测试1:
Error: Transaction reverted: function selector was not recognized and there's no fallback nor receive function
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注意
这里说的是让合约地址可以**以纯转账的方式**接收以太 而不是说合约地址上可以不存钱,
比如调用payable函数就不是"纯转账", 这时候是不需要receive函数的
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function giveMoney() external payable {
console.log(
"[LOG] giveMoney, from:",
msg.sender,
", value:",
msg.value
);
}
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Fallback
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fallback() external {
//...
}
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或
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fallback() external payable{
//...
}
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基本作用:
当对合约调用一个不存在的函数时, fallback()将被执行
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// SPDX-License-Identifier: SEE LICENSE IN LICENSE
pragma solidity ^0.8.4;
import "hardhat/console.sol";
contract Callee {
fallback() external {
console.log("[LOG] you called one function which not exist ");
}
function getBalance() public view returns (uint) {
return address(this).balance;
}
}
contract Caller {
function callFunctionDoesNotExist(address _addr) public {
(bool success, ) = _addr.call(
abi.encodeWithSignature("doesNotExist()")
);
console.log("[LOG] address call return: ", success);
}
}
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const { ethers } = require('hardhat');
describe('Caller Contract Test Suits', function () {
it("测试调用不存在的函数", async function () {
let facotry = await ethers.getContractFactory("Caller");
let callerContract = await facotry.deploy();
facotry = await ethers.getContractFactory("Callee");
let receiveContract = await facotry.deploy();
await callerContract.callFunctionDoesNotExist(receiveContract.address);
});
});
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输出
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❯ npx hardhat test ./test/caller.test.js
Compiled 1 Solidity file successfully
Caller Contract Test Suits
[LOG] you called one function which not exist
[LOG] address call return: true
✔ 测试调用不存在的函数 (1080ms)
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附加作用(不推荐的)
当没有receive函数, 并且 fallback() 为 payable时 (也就是fallback() external payable), 充当receive的角色.
2300gas
receive 和 fallback 由于并非用户明确调用, 所以gas是定死的2300, 那么不要在他们的函数体中做高消耗gas的操作, 记记日志就不错了:)
DMEO代码
https://github.com/yinhui1984/imagehosting/blob/main/images/1669789488023678000.7z
下载后, 调用makefile: make init 来安装依赖
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.PHONY: test
init:
@echo "Initializing the project"
npm init -y
npm install hardhat
npm install @nomicfoundation/hardhat-toolbox
compile:
npx hardhat compile
test:
@echo "\033[31m运行使用js编写的测试用例\033[m"
@# 后面跟文件路径可以只运行某个测试文件， 比如 npx hardhat test ./test/ZombieAttack.test.js
npx hardhat test
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