NestJS Enterprise Backend APIs · Pelajaran

Pengujian Unit Kontrak Cerdas

Pelajari cara menulis pengujian unit yang menyeluruh untuk kontrak Solidity Anda guna memastikan kebenaran, keamanan, dan perilaku yang diharapkan.

Pengujian Unit Kontrak Cerdas adalah pelajaran NestJS Enterprise Backend APIs gratis di CoddyKit. Ini adalah pelajaran 4 dari 6. Kamu bisa membaca pelajaran lengkapnya di bawah secara gratis — lalu praktikkan langsung di browser dengan editor kode bawaan dan tutor AI 24/7. Ini adalah bagian dari jalur belajar NestJS Enterprise Backend APIs, dan progresmu tersinkronisasi di web dan aplikasi CoddyKit. Kursus NestJS Enterprise Backend APIs mencakup 6 pelajaran total.

Bagian dari pelajaran ini belum diterjemahkan dan ditampilkan dalam bahasa Inggris.

Unit Testing Smart Contracts

Welcome to unit testing for smart contracts! This lesson will guide you through writing effective tests for your Solidity code.

Unit tests are crucial in traditional software development, but they are absolutely vital in the blockchain world due to the immutable nature of smart contracts and the financial value they often secure.

Why Test Smart Contracts?

Unlike regular applications, smart contracts, once deployed, cannot be easily changed. Bugs can lead to significant financial losses or system failures.

Immutability: Deployed contracts are permanent.
High Stakes: Often manage valuable assets.
Security: Protect against vulnerabilities.
Reliability: Ensure functions behave as expected.
Gas Costs: Bugs can waste user funds.

Thorough testing helps catch issues before deployment.

Introducing Hardhat for Testing

Hardhat is a popular Ethereum development environment that includes a powerful testing framework. It provides a local Ethereum network (Hardhat Network) for fast, isolated testing.

Local Network: Deploy and test without real gas fees.
Ethers.js Integration: Interact with contracts using a familiar JavaScript library.
Debugging: Tools for understanding transaction failures.

We'll use Hardhat to write our unit tests.

Basic Contract for Testing

Let's start with a simple Solidity contract that we'll use for our unit tests. This Counter contract allows us to increment, decrement, and get a count.

Copy and save this as contracts/Counter.sol in your Hardhat project.

pragma solidity ^0.8.0;

contract Counter {
  uint public count;

  constructor() {
    count = 0;
  }

  function increment() public {
    count += 1;
  }

  function decrement() public {
    require(count > 0, "Count cannot be negative");
    count -= 1;
  }

  function getCount() public view returns (uint) {
    return count;
  }
}

Setting Up Your Test File

Hardhat expects test files to be in the test/ directory. We'll use Mocha for our test runner and Chai for assertions, both integrated with Hardhat.

describe(): Groups related tests.
it(): Defines an individual test case.
beforeEach(): Runs before each test in a describe block, useful for setup.

Let's create a file named test/Counter.js.

Deploying Your Contract in Tests

Before we can test our contract's functions, we need to deploy it to our local Hardhat network. The beforeEach block is perfect for this, ensuring a fresh deployment for every test.

Try running this test file. It should pass if your contract is correctly set up.

const { expect } = require("chai");
const { ethers } = require("hardhat");

describe("Counter", function () {
  let counter; // Declare 'counter' to be accessible in all tests

  beforeEach(async function () {
    const CounterFactory = await ethers.getContractFactory("Counter");
    counter = await CounterFactory.deploy();
    await counter.deployed(); // Wait for deployment to be confirmed
  });

  // A simple test to confirm deployment
  it("Should confirm the contract is deployed", async function () {
    expect(counter.address).to.not.be.null;
  });
});

Testing Initial State

The first thing to test is if our contract's initial state is correct. Our Counter contract's count should start at 0.

We use expect() from Chai to make assertions about our contract's behavior. to.equal() checks for equality.

const { expect } = require("chai");
const { ethers } = require("hardhat");

describe("Counter", function () {
  let counter;

  beforeEach(async function () {
    const CounterFactory = await ethers.getContractFactory("Counter");
    counter = await CounterFactory.deploy();
    await counter.deployed();
  });

  it("Should return the initial count of 0", async function () {
    expect(await counter.getCount()).to.equal(0);
  });

  it("Should confirm the contract is deployed", async function () {
    expect(counter.address).to.not.be.null;
  });
});

Testing State Changes (Increment)

Now let's test a function that changes the contract's state. After calling increment(), we expect the count to increase by one.

Remember that state-changing functions need to be awaited because they involve a transaction on the blockchain.

const { expect } = require("chai");
const { ethers } = require("hardhat");

describe("Counter", function () {
  let counter;

  beforeEach(async function () {
    const CounterFactory = await ethers.getContractFactory("Counter");
    counter = await CounterFactory.deploy();
    await counter.deployed();
  });

  it("Should return the initial count of 0", async function () {
    expect(await counter.getCount()).to.equal(0);
  });

  it("Should increment the count by 1", async function () {
    await counter.increment();
    expect(await counter.getCount()).to.equal(1);
  });

  it("Should confirm the contract is deployed", async function () {
    expect(counter.address).to.not.be.null;
  });
});

Testing Function Logic (Decrement)

We can also test the decrement() function. For this, we first need to increment the counter to ensure count is greater than zero.

This shows how tests can involve a sequence of operations to reach a desired state before asserting the outcome.

const { expect } = require("chai");
const { ethers } = require("hardhat");

describe("Counter", function () {
  let counter;

  beforeEach(async function () {
    const CounterFactory = await ethers.getContractFactory("Counter");
    counter = await CounterFactory.deploy();
    await counter.deployed();
  });

  it("Should return the initial count of 0", async function () {
    expect(await counter.getCount()).to.equal(0);
  });

  it("Should increment the count by 1", async function () {
    await counter.increment();
    expect(await counter.getCount()).to.equal(1);
  });

  it("Should decrement the count by 1", async function () {
    await counter.increment(); // First increment to make count > 0
    await counter.decrement();
    expect(await counter.getCount()).to.equal(0);
  });

  it("Should confirm the contract is deployed", async function () {
    expect(counter.address).to.not.be.null;
  });
});

Testing for Expected Reverts

Smart contracts often use require() or revert() to enforce conditions. It's vital to test that these conditions correctly trigger a revert when violated.

Chai's to.be.revertedWith() assertion allows us to check for specific error messages.

const { expect } = require("chai");
const { ethers } = require("hardhat");

describe("Counter", function () {
  let counter;

  beforeEach(async function () {
    const CounterFactory = await ethers.getContractFactory("Counter");
    counter = await CounterFactory.deploy();
    await counter.deployed();
  });

  it("Should return the initial count of 0", async function () {
    expect(await counter.getCount()).to.equal(0);
  });

  it("Should increment the count by 1", async function () {
    await counter.increment();
    expect(await counter.getCount()).to.equal(1);
  });

  it("Should decrement the count by 1", async function () {
    await counter.increment();
    await counter.decrement();
    expect(await counter.getCount()).to.equal(0);
  });

  it("Should revert if decrementing from zero", async function () {
    await expect(counter.decrement()).to.be.revertedWith("Count cannot be negative");
  });

  it("Should confirm the contract is deployed", async function () {
    expect(counter.address).to.not.be.null;
  });
});

Quick Check: Test Assertions

What are the key benefits of using expect().to.be.revertedWith("...") in smart contract unit tests?

Recap: Unit Testing Power

In this lesson, you've learned the critical importance of unit testing for smart contracts and how to write effective tests using Hardhat, Mocha, and Chai.

Smart contracts require rigorous testing due to their immutability.
Hardhat provides a powerful local environment for fast testing.
You can test initial states, state changes, function logic, and expected reverts.

Mastering unit testing is a fundamental skill for any secure and reliable DApp developer.

Pertanyaan yang Sering Diajukan

Apakah pelajaran “Pengujian Unit Kontrak Cerdas” gratis?

Ya — teks lengkap “Pengujian Unit Kontrak Cerdas” gratis dibaca di sini di web. Untuk praktiknya secara interaktif (editor kode bawaan dan tutor AI 24/7) dan buka sisa kursus NestJS Enterprise Backend APIs, upgrade ke CoddyKit PRO. Kursus NestJS Enterprise Backend APIs mencakup 6 pelajaran total.

Apa yang akan aku pelajari di “Pengujian Unit Kontrak Cerdas”?

Pelajari cara menulis pengujian unit yang menyeluruh untuk kontrak Solidity Anda guna memastikan kebenaran, keamanan, dan perilaku yang diharapkan. Kamu berlatih NestJS Enterprise Backend APIs dengan kode praktik yang langsung kamu jalankan di browser, dan tutor AI 24/7 menjawab pertanyaanmu saat kamu mengerjakan pelajaran ini.

Apakah aku perlu pengalaman untuk memulai NestJS Enterprise Backend APIs?

Tidak diperlukan pengalaman sebelumnya. NestJS Enterprise Backend APIs di CoddyKit dirancang untuk pemula hingga pelajar tingkat lanjut, jadi kamu bisa memulai di sini atau dari awal dan belajar sesuai kecepatan kamu sendiri. Ini adalah pelajaran 4 dari 6.

Berapa lama pelajaran “Pengujian Unit Kontrak Cerdas” memakan waktu?

Sebagian besar pelajaran CoddyKit memakan waktu sekitar 5–10 menit. Setiap pelajaran ringkas dan interaktif, jadi kamu membuat kemajuan stabil dan melanjutkan dari tempat kamu tinggalkan di web dan aplikasi.

Bisakah aku menulis dan menjalankan kode dalam pelajaran NestJS Enterprise Backend APIs ini?

Ya. Setiap pelajaran NestJS Enterprise Backend APIs menyertakan editor kode bawaan, jadi kamu menulis dan menjalankan kode nyata langsung di browser dan mendapatkan umpan balik AI instan — tidak diperlukan penyiapan lokal.

Semua pelajaran dalam kursus ini

Pengujian Unit dan E2E
Kerangka Kerja Hardhat dan Truffle
Pengujian Kinerja API
Pengujian Unit Kontrak Cerdas
Kontainerisasi dengan Docker dan Kubernetes
Penerapan ke Jaringan Uji dan Jaringan Utama

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