init hardhat

.gitignore

@@ -27,3 +27,15 @@ coverage/
 
 # Playwright
 /playwright/
+
+node_modules
+.env
+coverage
+coverage.json
+typechain
+typechain-types
+
+# Hardhat files
+cache
+artifacts
+

contracts/Lock.sol

@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.9;
+
+// 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.config.cjs

@@ -0,0 +1,6 @@
+require("@nomicfoundation/hardhat-toolbox");
+
+/** @type import('hardhat/config').HardhatUserConfig */
+module.exports = {
+  solidity: "0.8.19",
+};

package.json

@@ -12,7 +12,6 @@
 		"test": "npm run test:unit && npm run test:e2e",
 		"test:unit": "vitest --coverage --run",
 		"test:e2e": "playwright test",
-
 		"install:test": "playwright install --with-deps"
 	},
 	"dependencies": {
@@ -22,10 +21,13 @@
 		"@dzeio/object-util": "^1",
 		"@dzeio/url-manager": "^1",
 		"astro": "^2",
+		"ethers": "^6.7.0",
+		"hardhat": "^2.17.1",
 		"lucide-astro": "^0.262.0",
 		"tailwindcss": "^3"
 	},
 	"devDependencies": {
+		"@nomicfoundation/hardhat-toolbox": "^3.0.0",
 		"@playwright/test": "^1.36.1",
 		"@types/node": "^20",
 		"@vitest/coverage-v8": "^0.33.0",

scripts/deploy.js

@@ -0,0 +1,24 @@
+// We require the Hardhat Runtime Environment explicitly here. This is optional
+// but useful for running the script in a standalone fashion through `node <script>`.
+//
+// You can also run a script with `npx hardhat run <script>`. If you do that, Hardhat
+// will compile your contracts, add the Hardhat Runtime Environment's members to the
+// global scope, and execute the script.
+import hre from "hardhat";
+
+const currentTimestampInSeconds = Math.round(Date.now() / 1000);
+const unlockTime = currentTimestampInSeconds + 60;
+
+const lockedAmount = hre.ethers.parseEther("0.001");
+
+const lock = await ethers.deployContract("Lock", [unlockTime], {
+  value: lockedAmount,
+});
+
+await lock.waitForDeployment();
+
+console.log(
+  `Lock with ${ethers.formatEther(
+    lockedAmount
+  )}ETH and unlock timestamp ${unlockTime} deployed to ${lock.target}`
+);

test/Lock.js

@@ -0,0 +1,126 @@
+import {
+  time,
+  loadFixture,
+} from "@nomicfoundation/hardhat-toolbox/network-helpers.js";
+import { anyValue } from "@nomicfoundation/hardhat-chai-matchers/withArgs.js";
+import { expect } from "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]
+        );
+      });
+    });
+  });
+});