Best Development Practices for Applications and Smart Contracts: A Complete Guide

Today Blockchain has evolved rapidly, and with these technological changes, creating a project is no longer just about having a groundbreaking idea; it’s about strategic planning, execution, and ongoing enhancement. Blockchain has become similar to crafting an art piece with new technologies, platforms, and practices emerging rapidly. So, whether you’re starting fresh or are already a pro knowing what steps to follow can make all the difference.

This article walks you through key practices that will help you build a blockchain project that’s not only innovative but also secure, scalable, and built for the long run.

Key Sections:

• Testing blockchain applications
• Auditing smart contracts
• Gas optimization techniques
• Managing upgrades and forks

Imagine you are building a castle of blocks with your friends. Now everybody just randomly starts adding pieces without planning and strategizing. What do you think would happen? Pretty soon, the castle might look messy or even fall apart! The same thing can happen in blockchain development, only here you have much more to lose.

So, following best practices isn’t just about being “extra careful”; it’s about creating something strong, safe, and future-proof, so users and developers can count on it long-term. In the world of blockchain, a good foundation matters more than anything!

Let's get started and have a look at the Best practices to follow in Blockchain development.

Testing Blockchain Application 

Why do we need testing?  

Testing is the most important step of the Blockchain development life cycle. It ensures that applications function as expected and finds out issues and bugs if any. Since blockchain is decentralized it can lead a widespread errors that include financial loss and reputational damage. Hence testing ensures the security, functionality, and performance of your applications. A well-tested application not only protects users but also enhances trust in the technology.

Types of Testing 

• Unit testing: In unit testing, we focus on the smallest part of the application and treat it as an individual unit to ensure it performs as expected. By isolating and testing these components, developers can quickly identify and fix issues before they impact other parts of the code. 

Unit tests catch the bugs at an early stage and are a safety net, making it easier and less costly to fix them. Due to unit testing, if there are any and we resolve it, the new code doesn't break the existing functionality.

Here’s an example of a Solidity Unit Test with Hardhat and Chai

// Sample Solidity Smart Contract // SPDX-License-Identifier: MIT pragma solidity ^0.8.0; contract Token {     mapping(address => uint256) public balances;     constructor() {         balances[msg.sender] = 1000; // Initial balance for the contract deployer     }     function transfer(address recipient, uint256 amount) public returns (bool) {         require(balances[msg.sender] >= amount, "Insufficient balance");         balances[msg.sender] -= amount;         balances[recipient] += amount;         return true;     } }

• Integration Test: Integration testing ensures that different modules or components work together as intended. This type of testing is vital because even if individual units function correctly, they might not integrate seamlessly when combined.

Integration testing helps to identify and resolve issues arising from the interactions between different microservices in your application and helps in more cohesive functioning.

Example Code Snippet for Integration Testing:

// Integration test for contract interaction const { expect } = require("chai"); describe("Integration test between Token and Marketplace contracts", function () {   it("should allow token transfer for marketplace purchases", async function () {     const [owner, buyer] = await ethers.getSigners();     const Token = await ethers.getContractFactory("Token");     const Marketplace = await ethers.getContractFactory("Marketplace");     const token = await Token.deploy();     const marketplace = await Marketplace.deploy(token.address);     await token.deployed();     await marketplace.deployed();     // Transfer tokens to the buyer for marketplace use     await token.transfer(buyer.address, 500);     expect(await token.balances(buyer.address)).to.equal(500);     // Buyer approves tokens for marketplace contract    await token.connect(buyer).approve(marketplace.address, 200);     const purchaseTx = await marketplace.connect(buyer).buyItem(1, 200);     await purchaseTx.wait();     // Check balances post-purchase    expect(await token.balances(buyer.address)).to.equal(300);     expect(await token.balances(marketplace.address)).to.equal(200);   }); });

• Functional Testing: Functional testing ensures that the application meets the defined requirements and specifications. It tests the complete functionality of the software, ensuring that all user actions produce the desired outcome.

Functional testing is important because it assures that the application performs as intended in real-world scenarios.

// Functional test to validate smart contract requirements const { expect } = require("chai"); describe("Token contract - Functional Testing", function () {   it("should not allow transfer when balance is insufficient", async function () {     const [owner, addr1] = await ethers.getSigners();     const Token = await ethers.getContractFactory("Token");     const token = await Token.deploy();    await token.deployed();     // Attempting a transfer larger than balance     await expect(token.connect(addr1).transfer(owner.address, 50))       .to.be.revertedWith("Insufficient balance");   }); });

• Performance Testing: Performance testing evaluates how your blockchain application performs under different conditions, such as varying user loads or network speeds. It involves measuring responsiveness, stability, and scalability.

This testing ensures that the application can handle all real-world stress efficiently and how good and reliable the application is for the users. This is crucial for maintaining a good user experience and operational integrity, especially as the number of users grows. The metric used for testing is the number of transactions the blockchain can process per second (TPS).

Performance Testing is of three types:

• Load Testing: Determines how the application performs under expected user loads.
• Stress Testing:  Pushes the system beyond its limits to see how it behaves under extreme conditions.
• Scalability Testing:  Checks if the application can scale up or down based on changing user demands.

// Script for load testing using Web3.js and a test framework const Web3 = require('web3'); const web3 = new Web3(new Web3.providers.HttpProvider('http://localhost:8545')); async function performLoadTest(contractInstance, iterations, account) {   for (let i = 0; i < iterations; i++) {     try {       await contractInstance.methods.transfer('0xRecipientAddress', 1).send({ from: account });       console.log(`Transaction ${i + 1} completed`);     } catch (error) {      console.error(`Transaction ${i + 1} failed:`, error);     }   } } // Sample call (async () => {   const contract = new web3.eth.Contract(abi, contractAddress);   const accounts = await web3.eth.getAccounts();   await performLoadTest(contract, 1000, accounts[0]); // Run 1000 transactions })();

• Security Testing: Security tests evaluate the entire security of the application and detect vulnerabilities that could be exploited, weaknesses in smart contracts, or data leaks. Blockchain projects often involve sensitive data and financial transactions, making security testing non-negotiable.

// Sample vulnerable Solidity contract function withdraw(uint amount) public {     require(balance[msg.sender] >= amount);     (bool success, ) = msg.sender.call{value: amount}(""); // Vulnerable line     require(success);    balance[msg.sender] -= amount; } // Reentrancy attack simulation using JavaScript/Hardhat const { ethers } = require("hardhat"); describe("Reentrancy attack simulation", function () {   it("should exploit reentrancy vulnerability", async function () {     const [attacker, victim] = await ethers.getSigners();     const VulnerableContract = await ethers.getContractFactory("VulnerableContract");     const AttackerContract = await ethers.getContractFactory("AttackerContract");     const vulnerable = await VulnerableContract.deploy();    await vulnerable.deployed();    const attackerInstance = await AttackerContract.deploy(vulnerable.address);    await attackerInstance.deployed();     // Attack scenario    await attackerInstance.connect(attacker).attack({ value: ethers.utils.parseEther("1") });     expect(await ethers.provider.getBalance(vulnerable.address)).to.equal(0); // Check drained balance   }); });

Tools You need 

You must have a good idea about different types of testing and how to incorporate them at different stages. Now, let's look at the tools and libraries that come in handy while conducting these tests.

• Truffle suite: It is a comprehensive development framework designed for Ethereum that not only supports testing but also deployment and contract management.
• Ganache: Ganache is a personal Ethereum blockchain that runs on your local machine. It allows developers to deploy contracts, run tests, and execute commands without connecting to a public testnet or mainnet.
• Mocha and Chai:  Mocha is a JavaScript testing framework that runs on Node.js, and Chai is an assertion library that works seamlessly with Mocha to provide test case validations.
• Mythril:  Mythril is an open-source security analysis tool designed for Ethereum smart contracts.

Also, read our article on testing and deploying smart contracts

Best Practices

1. Automate Testing: Automating the testing process ensures that code changes are verified before deployment. Implement continuous integration (CI) pipelines using tools like GitHub Actions, Jenkins, or GitLab CI/CD to automate test runs after every code update.
2. Test Early and Often: Start testing your application as soon as development starts and continue testing throughout the development lifecycle. This can help to detect and resolve the issue before it gets complex and costly to resolve.
3. Write Clear Test Cases
4. Code Coverage Tools: Use tools like solidity-coverage to identify untested parts of your code.
5. Mock External Services: When testing contracts that interact with oracles or external data providers, use mocks to simulate responses and ensure reliable tests.

Auditing smart contracts

Significance of Auditing

Auditing plays an important role in blockchain as it ensures that the application is secure and functions as intended.. Smart contracts often manage substantial amounts of assets, and even a minor coding flaw can lead to severe financial loss, security breaches, and loss of trust among users.To prevent the hassles audits must be conducted.This preventive step is a sviour for developers and reassures users that their assets and interactions are safe.

Auditing Process  

The typical auditing takes place in stages: 

1. Initial Review: Initially just analyze  the contract’s code structure, functionality, and documentation to understand its overall intent and logic.

// Example: Check function visibility to avoid unintentional exposure function internalLogic() internal {      // Code logic  }

2. Automated Analysis:  Employ tools like MythX, Slither, and Oyente to detect known vulnerabilities such as reentrancy attacks, integer overflows, and unchecked external calls.

uint8 a = 255;  a += 1; // This would overflow without proper checks

3. Manual Code Review: A detailed, manual line-by-line review identifies logical errors and potential vulnerabilities that automated tools might miss. This includes examining business logic and security issues like race conditions.

// Example of a reentrancy vulnerability function withdraw(uint256 _amount) public {     require(balances[msg.sender] >= _amount, "Insufficient balance");     (bool success, ) = msg.sender.call{value: _amount}("");     require(success, "Transfer failed");     balances[msg.sender] -= _amount; // Reduces balance after the transfer (reentrancy risk) }

4. Testing and Simulation:  Use frameworks such as Hardhat or Truffle to create unit tests and simulate different scenarios to identify vulnerabilities that could occur under various conditions.

// Example test in JavaScript for Hardhat describe("Audit test for smart contract", function () {   it("Should prevent non-owners from calling restricted functions", async function () {     await expect(contract.connect(nonOwner).restrictedFunction()).to.be.revertedWith("Only the owner can call this function");   }); });

5. Reporting and Recommendations: Prepare a comprehensive report outlining identified vulnerabilities, categorized by severity, and provide recommendations for addressing each issue.

Audit Tools  

To conduct a thorough audit you needs tools as follows:

• MythX: An advanced security analysis service for Ethereum smart contracts that scans for a wide array of vulnerabilities.
• Slither: A powerful open-source static analysis tool that flags issues such as unused variables and compliance with Solidity best practices.
• Oyente: Examines Ethereum bytecode for known vulnerabilities, ensuring code robustness.
• Hardhat: A development environment that includes testing and debugging capabilities, making it useful for in-depth contract analysis.

Best Practices

• Keep Code simple
• Ensure contracts can handle errors without partial execution or unintended consequences.
• Use safe external calls 

Gas optimization techniques

Understanding Gas 

Gas optimization plays a crucial role in keeping transaction costs low and ensuring that smart contracts operate smoothly. To optimize effectively, it’s important to understand how gas works. Gas fees reflect the computational power needed to execute operations on the Ethereum Virtual Machine (EVM). Each operation has its own gas cost, and contracts with high gas consumption can become too expensive to use, especially as network congestion increases.

 Optimization Techniques 

One common optimization technique is to use fixed-size arrays rather than dynamic ones, as they require less gas. Additionally, when dealing with variables that don’t need to persist beyond a function’s execution, using memory instead of storage is beneficial. This is because reading from and writing to storage is far more costly than using memory. For example, when iterating over data within a loop, using memory variables can significantly improve performance and reduce gas costs.

function processData(uint256[] memory data) public pure returns (uint256) {     uint256 sum = 0;     for (uint i = 0; i < data.length; i++) {         sum += data[i];     }     return sum; // Efficient use of memory }

Best Practices

Managing upgrades and forks

Understanding Upgrades 

Upgrading smart contracts can be tricky because blockchain is inherently immutable. However, there are strategies to work around this limitation, with proxy contracts being one of the most effective solutions. A proxy contract acts as a go-between, directing function calls to the main contract that holds the core logic. When an update or improvement is needed, developers only replace the contract containing the logic, while the proxy and storage remain intact. This approach ensures that all existing data stays safe and consistent, even as the underlying code is improved or fixed.

contract Proxy {     address implementation;     function upgrade(address _newImplementation) external {         implementation = _newImplementation;     }     fallback() external payable {         (bool success, ) = implementation.delegatecall(msg.data);         require(success, "Delegate call failed");     } }

Upgrade Strategies 

Upgrading smart contracts on a blockchain is no small task because the data is designed to be permanent and unchangeable. To work around this, developers often use proxy contracts. A proxy acts like a middleman, routing calls to the main contract where the logic lives. If updates or fixes are needed, only the logic contract gets replaced while the proxy and storage parts stay the same. This approach keeps existing data safe and intact while allowing the code to evolve over time.

Handling Forks 

Forks can be a major challenge, as they involve changes to a blockchain’s underlying rules or even the creation of a new chain altogether. To handle forks effectively, developers need a proactive approach that keeps their smart contracts running smoothly. This often means testing how contracts behave in fork scenarios and preparing contingency plans in case changes need to be made.

Flexibility is critical. Developers should consider adding features that let them pause functions or migrate the contract if necessary. Keeping users informed and providing clear documentation is just as important. It ensures trust and transparency, which can make navigating a fork much easier for everyone involved.

Best Practices

• Use Use proxy contracts to separate the logic from data storage, allowing for seamless updates without disrupting stored data.
• Implement upgradability frameworks such as OpenZeppelin’s Transparent Proxy Pattern for reliable and simplified upgrade management.
• Maintain modular contract structures, enabling independent updates of different contract components for better flexibility.
• Thoroughly test upgrades in a simulated environment before deploying changes to the mainnet.
• Incorporate pause and migration functions to halt operations or migrate data safely if an upgrade or change is needed.
• Ensure backward compatibility to avoid breaking existing functionalities for users.
• Document the upgrade process and changes in detail for future reference and transparency.

Conclusion

In blockchain development, following best practices is key to building secure, efficient, and easy-to-use applications. Writing clean and maintainable code makes it easier to manage and scale your project. Focus on security by using trusted libraries and thoroughly testing your code to avoid vulnerabilities. Using proxy contracts for upgrades and being ready for forks help your project stay flexible. Keep communication open with users to build trust and ensure your app remains reliable. By sticking to these practices, you can create solid blockchain applications that stand the test of time.Keep Learning and Happy Coding!!