注：本文不是教程，仅用于自己记录学习经验。
准备部分
安装hardhat
use npm7+
npm install --save-dev hardhat
开始构建
创建一个简单的项目
使用npx hardhat init命令初始化项目文件夹。
$ npx hardhat init
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👷 Welcome to Hardhat v2.22.2 👷
? What do you want to do? …
❯ Create a JavaScript project
Create a TypeScript project
Create a TypeScript project (with Viem)
Create an empty hardhat.config.js
Quit
在运行命令后，系统会让选择不同项目语言，默认的是js，本系列也是基于js的基本语言。
运行tasks
hardhat允许你通过在项目文件夹下运行npx hardhat来快速了解可用内容和查看正在发生的情况。
$ npx hardhat
Hardhat version 2.9.9
Usage: hardhat [GLOBAL OPTIONS] <TASK> [TASK OPTIONS]
GLOBAL OPTIONS:
--config A Hardhat config file.
--emoji Use emoji in messages.
--help Shows this message, or a task's help if its name is provided
--max-memory The maximum amount of memory that Hardhat can use.
--network The network to connect to.
--show-stack-traces Show stack traces.
--tsconfig A TypeScript config file.
--verbose Enables Hardhat verbose logging
--version Shows hardhat's version.
AVAILABLE TASKS:
check Check whatever you need
clean Clears the cache and deletes all artifacts
compile Compiles the entire project, building all artifacts
console Opens a hardhat console
coverage Generates a code coverage report for tests
flatten Flattens and prints contracts and their dependencies
help Prints this message
node Starts a JSON-RPC server on top of Hardhat Network
run Runs a user-defined script after compiling the project
test Runs mocha tests
typechain Generate Typechain typings for compiled contracts
verify Verifies contract on Etherscan
To get help for a specific task run: npx hardhat help [task]
同时，hardhat也允许你自己编写tasks，具体可以查看官方文档Writing tasks和Creating a task
编译合约
以下是contracts/文件夹下的Lock.sol，也是hardhat在初始化项目文件夹时自动构建的示例合约。
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.24;
// Uncomment this line to use console.log
// import "hardhat/console.sol";
contract Lock {
uint public unlockTime;
address payable public owner;
event Withdrawal(uint amount, uint when);
constructor(uint _unlockTime) payable {
require(
block.timestamp < _unlockTime,
"Unlock time should be in the future"
);
unlockTime = _unlockTime;
owner = payable(msg.sender);
}
function withdraw() public {
// Uncomment this line, and the import of "hardhat/console.sol", to print a log in your terminal
// console.log("Unlock time is %o and block timestamp is %o", unlockTime, block.timestamp);
require(block.timestamp >= unlockTime, "You can't withdraw yet");
require(msg.sender == owner, "You aren't the owner");
emit Withdrawal(address(this).balance, block.timestamp);
owner.transfer(address(this).balance);
}
}
运行npx hardhat compile，hardhat会自动编译contracts/文件夹下所有合约。
当然，也可以指定合约进行编译。
运行npx hardhat compile ./contracts/Lock.sol将达到同样的效果。
除此之外，还可以运行npx hardhat compile --help来查看npx hardhat compile的具体情况。
$ npx hardhat compile --help
Hardhat version 2.22.2
Usage: hardhat [GLOBAL OPTIONS] compile [--concurrency <INT>] [--force] [--no-typechain] [--quiet]
OPTIONS:
--concurrency Number of compilation jobs executed in parallel. Defaults to the number of CPU cores - 1 (default: 15)
--force Force compilation ignoring cache
--no-typechain Skip Typechain compilation
--quiet Makes the compilation process less verbose
compile: Compiles the entire project, building all artifacts
For global options help run: hardhat help
测试合约
hardhat允许使用并集成了Mocha, Chai, Ethers.js和Hardhat Ignition等测试工具。
在test/文件夹下，同样有一个hardhat初始化时为项目自动生成的测试文件：
const {
time,
loadFixture,
} = require("@nomicfoundation/hardhat-toolbox/network-helpers");
const { anyValue } = require("@nomicfoundation/hardhat-chai-matchers/withArgs");
const { expect } = require("chai");
describe("Lock", function () {
// We define a fixture to reuse the same setup in every test.
// We use loadFixture to run this setup once, snapshot that state,
// and reset Hardhat Network to that snapshot in every test.
async function deployOneYearLockFixture() {
const ONE_YEAR_IN_SECS = 365 * 24 * 60 * 60;
const ONE_GWEI = 1_000_000_000;
const lockedAmount = ONE_GWEI;
const unlockTime = (await time.latest()) + ONE_YEAR_IN_SECS;
// Contracts are deployed using the first signer/account by default
const [owner, otherAccount] = await ethers.getSigners();
const Lock = await ethers.getContractFactory("Lock");
const lock = await Lock.deploy(unlockTime, { value: lockedAmount });
return { lock, unlockTime, lockedAmount, owner, otherAccount };
}
describe("Deployment", function () {
it("Should set the right unlockTime", async function () {
const { lock, unlockTime } = await loadFixture(deployOneYearLockFixture);
expect(await lock.unlockTime()).to.equal(unlockTime);
});
it("Should set the right owner", async function () {
const { lock, owner } = await loadFixture(deployOneYearLockFixture);
expect(await lock.owner()).to.equal(owner.address);
});
it("Should receive and store the funds to lock", async function () {
const { lock, lockedAmount } = await loadFixture(
deployOneYearLockFixture
);
expect(await ethers.provider.getBalance(lock.target)).to.equal(
lockedAmount
);
});
it("Should fail if the unlockTime is not in the future", async function () {
// We don't use the fixture here because we want a different deployment
const latestTime = await time.latest();
const Lock = await ethers.getContractFactory("Lock");
await expect(Lock.deploy(latestTime, { value: 1 })).to.be.revertedWith(
"Unlock time should be in the future"
);
});
});
describe("Withdrawals", function () {
describe("Validations", function () {
it("Should revert with the right error if called too soon", async function () {
const { lock } = await loadFixture(deployOneYearLockFixture);
await expect(lock.withdraw()).to.be.revertedWith(
"You can't withdraw yet"
);
});
it("Should revert with the right error if called from another account", async function () {
const { lock, unlockTime, otherAccount } = await loadFixture(
deployOneYearLockFixture
);
// We can increase the time in Hardhat Network
await time.increaseTo(unlockTime);
// We use lock.connect() to send a transaction from another account
await expect(lock.connect(otherAccount).withdraw()).to.be.revertedWith(
"You aren't the owner"
);
});
it("Shouldn't fail if the unlockTime has arrived and the owner calls it", async function () {
const { lock, unlockTime } = await loadFixture(
deployOneYearLockFixture
);
// Transactions are sent using the first signer by default
await time.increaseTo(unlockTime);
await expect(lock.withdraw()).not.to.be.reverted;
});
});
describe("Events", function () {
it("Should emit an event on withdrawals", async function () {
const { lock, unlockTime, lockedAmount } = await loadFixture(
deployOneYearLockFixture
);
await time.increaseTo(unlockTime);
await expect(lock.withdraw())
.to.emit(lock, "Withdrawal")
.withArgs(lockedAmount, anyValue); // We accept any value as `when` arg
});
});
describe("Transfers", function () {
it("Should transfer the funds to the owner", async function () {
const { lock, unlockTime, lockedAmount, owner } = await loadFixture(
deployOneYearLockFixture
);
await time.increaseTo(unlockTime);
await expect(lock.withdraw()).to.changeEtherBalances(
[owner, lock],
[lockedAmount, -lockedAmount]
);
});
});
});
});
运行npx hardhat test，hardhat将自动测试test/文件夹下所有测试文件。
$ npx hardhat test
Compiled 2 Solidity files successfully
Lock
Deployment
✔ Should set the right unlockTime (610ms)
✔ Should set the right owner
✔ Should receive and store the funds to lock
✔ Should fail if the unlockTime is not in the future
Withdrawals
Validations
✔ Should revert with the right error if called too soon
✔ Should revert with the right error if called from another account
✔ Shouldn't fail if the unlockTime has arrived and the owner calls it
Events
✔ Should emit an event on withdrawals
Transfers
✔ Should transfer the funds to the owner
9 passing (790ms)
同样的，也可以通过npx hardhat test ./test/Lock.js来指定测试文件。
运行npx hardhat test --help，hardhat会显示test命令相关的详细信息。
$ npx hardhat test --help
Hardhat version 2.22.2
Usage: hardhat [GLOBAL OPTIONS] test [--bail] [--grep <STRING>] [--no-compile] [--parallel] [...testFiles]
OPTIONS:
--bail Stop running tests after the first test failure
--grep Only run tests matching the given string or regexp
--no-compile Don't compile before running this task
--parallel Run tests in parallel
POSITIONAL ARGUMENTS:
testFiles An optional list of files to test (default: [])
test: Runs mocha tests
For global options help run: hardhat help
部署合约
hardhat允许使用Ignition模块部署合约，合约部署文件放置在ignition/modules文件夹下。
以下是hardhat初始化时为Lock合约自动生成的部署文件Lock.js：
const { buildModule } = require("@nomicfoundation/hardhat-ignition/modules");
const JAN_1ST_2030 = 1893456000;
const ONE_GWEI = 1_000_000_000n;
module.exports = buildModule("LockModule", (m) => {
const unlockTime = m.getParameter("unlockTime", JAN_1ST_2030);
const lockedAmount = m.getParameter("lockedAmount", ONE_GWEI);
const lock = m.contract("Lock", [unlockTime], {
value: lockedAmount,
});
return { lock };
});
运行npx hardhat ignition deploy ./ignition/modules/Lock.js，正常情况控制台将打印以下类似内容：
$ npx hardhat ignition deploy ./ignition/modules/Lock.js
Compiled 1 Solidity file successfully (evm target: paris).
You are running Hardhat Ignition against an in-process instance of Hardhat Network.
This will execute the deployment, but the results will be lost.
You can use --network <network-name> to deploy to a different network.
Hardhat Ignition 🚀
Deploying [ LockModule ]
Batch #1
Executed LockModule#Lock
[ LockModule ] successfully deployed 🚀
Deployed Addresses
LockModule#Lock - 0x5FbDB2315678afecb367f032d93F642f64180aa3
运行npx hardhat ignition --help，可以发现ignition命令详细信息。
$ npx hardhat ignition --help
Hardhat version 2.22.2
Usage: hardhat [GLOBAL OPTIONS] ignition <TASK> [TASK OPTIONS]
AVAILABLE TASKS:
deploy Deploy a module to the specified network
status Show the current status of a deployment
verify Verify contracts from a deployment against the configured block explorers
visualize Visualize a module as an HTML report
wipe Reset a deployment's future to allow rerunning
ignition: Deploy your smart contracts using Hardhat Ignition
For global options help run: hardhat help
当然，除了使用Ignition，在test中也可以部署合约。
连接hardhat网络
默认情况下，Hardhat 将在启动时启动一个新的内存中 Hardhat 网络实例。还可以以独立方式运行 Hardhat Network，以便外部客户端可以连接到它。这可以是钱包、Dapp 前端或 Hardhat Ignition deployment。
运行npx hardhat node，hardhat会自动生成模拟账户，每个用户具有10000ETH，同时控制台会打印用户公私钥信息。
注意：建议重新打开一个控制台运行，因为该网络实例在开启时需要一直占用当前控制台
$ npx hardhat node
Started HTTP and WebSocket JSON-RPC server at http://127.0.0.1:8545/
运行npx hardhat node --help，控制台将打印该命令详细信息：
$ npx hardhat node --help
Hardhat version 2.22.2
Usage: hardhat [GLOBAL OPTIONS] node [--fork <STRING>] [--fork-block-number <INT>] [--hostname <STRING>] [--port <INT>]
OPTIONS:
--fork The URL of the JSON-RPC server to fork from
--fork-block-number The block number to fork from
--hostname The host to which to bind to for new connections (Defaults to 127.0.0.1 running locally, and 0.0.0.0 in Docker)
--port The port on which to listen for new connections (default: 8545)
node: Starts a JSON-RPC server on top of Hardhat Network
For global options help run: hardhat help