Init hardhat project

hardhat/.gitignore

+node_modules
+.env
+
+# Hardhat files
+/cache
+/artifacts
+
+# TypeChain files
+/typechain
+/typechain-types
+
+# solidity-coverage files
+/coverage
+/coverage.json
+
+# Hardhat Ignition default folder for deployments against a local node
+ignition/deployments/chain-31337

hardhat/README.md

+# Sample Hardhat Project
+
+This project demonstrates a basic Hardhat use case. It comes with a sample contract, a test for that contract, and a Hardhat Ignition module that deploys that contract.
+
+Try running some of the following tasks:
+
+```shell
+npx hardhat help
+npx hardhat test
+REPORT_GAS=true npx hardhat test
+npx hardhat node
+npx hardhat ignition deploy ./ignition/modules/Lock.ts
+```

hardhat/contracts/Lock.sol

+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.28;
+
+// 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);
+    }
+}

hardhat/hardhat.config.ts

+import { HardhatUserConfig } from "hardhat/config";
+import "@nomicfoundation/hardhat-toolbox";
+
+const config: HardhatUserConfig = {
+  solidity: "0.8.28",
+};
+
+export default config;

hardhat/ignition/modules/Lock.ts

+// This setup uses Hardhat Ignition to manage smart contract deployments.
+// Learn more about it at https://hardhat.org/ignition
+
+import { buildModule } from "@nomicfoundation/hardhat-ignition/modules";
+
+const JAN_1ST_2030 = 1893456000;
+const ONE_GWEI: bigint = 1_000_000_000n;
+
+const LockModule = 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 };
+});
+
+export default LockModule;

hardhat/package.json

+{
+  "name": "hardhat-project",
+  "devDependencies": {
+    "@nomicfoundation/hardhat-toolbox": "^5.0.0",
+    "hardhat": "^2.22.19"
+  }
+}

hardhat/test/Lock.ts

+import {
+  time,
+  loadFixture,
+} from "@nomicfoundation/hardhat-toolbox/network-helpers";
+import { anyValue } from "@nomicfoundation/hardhat-chai-matchers/withArgs";
+import { expect } from "chai";
+import hre from "hardhat";
+
+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 hre.ethers.getSigners();
+
+    const Lock = await hre.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 hre.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 hre.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]
+        );
+      });
+    });
+  });
+});

hardhat/tsconfig.json

+{
+  "compilerOptions": {
+    "target": "es2020",
+    "module": "commonjs",
+    "esModuleInterop": true,
+    "forceConsistentCasingInFileNames": true,
+    "strict": true,
+    "skipLibCheck": true,
+    "resolveJsonModule": true
+  }
+}