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Hello Zeta

Hello Zeta

Overview

In this tutorial, we will walk through the process of creating, testing, and deploying a simple Solidity smart contract to the ZetaChain testnet using the Hardhat development environment. This tutorial will not feature any ZetaChain-specific features, but will instead focus on the basics of creating and testing a smart contract.

Set up your environment

note

This tutorial assumes that you have already completed the setup tutorial or cloned the template Hardhat project.

Create a new wallet and request tokens from the testnet faucet if you haven't done so already:

npx hardhat account --save

npx hardhat faucet

Create the contract

In the contracts directory, create a new file called HelloZeta.sol and add the following Solidity code to it:

hello/contracts/HelloZeta.sol

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This contract has a single function, helloZeta(), which returns a string "Hello Zeta".

Write a test for the contract

In the test directory, create a new file called HelloZeta.test.ts and add the following test code to it:

hello/test/HelloZeta.spec.ts

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First, we import the necessary modules. The expect function is imported from the Chai library, which is an assertion library that allows us to write human-readable assertions for our tests. The ethers object is imported from the Hardhat library, which provides a set of tools and utilities for smart contract development and testing.

We then define a test suite for the HelloZeta contract using the describe function from the Mocha framework. This function takes two arguments: a string describing the test suite, and a callback function that contains the tests.

Inside the test suite, we write a single test case using the it function. This function also takes two arguments: a string describing the test case, and an asynchronous callback function that performs the test.

In the test case, we begin by deploying the HelloZeta smart contract. We first get the contract factory using the ethers.getContractFactory() method, passing the name of the contract as an argument. Next, we deploy the contract by calling the deploy() method on the contract factory. We wait for the contract to be deployed using the deployed() method.

Once the contract is deployed, we call the helloZeta() function on the contract instance. This function should return the string "Hello Zeta". We store the result of this function call in a constant variable named result.

Finally, we check if the result matches our expectation using the expect function from the Chai library. We pass the result variable to the expect function and chain the to.equal() method to it, asserting that the result should be equal to the expected string "Hello Zeta".

In summary, this test suite is a simple example of testing a smart contract using Hardhat, Mocha, and Chai. It deploys the HelloZeta contract, calls the helloZeta() function, and checks if the returned result matches the expected value. This serves as a good starting point for understanding how to write tests for more complex smart contracts.

Run the test

Execute the following command to run the HelloZeta test using hardhat on the athens testnet:

npx hardhat test --network athens

HelloZeta
    ✔ Should return 'Hello Zeta' when calling helloZeta() (4709ms)

  1 passing (5s)

Create a deployment task

Now, we'll implement a simple Hardhat task that deploys a smart contract to the ZetaChain.

hello/tasks/deploy.ts

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Don't forget to import the deployment task in your hardhat.config.ts file.

hardhat.config.ts

import "./tasks/deploy";

The deployment task defines an asynchronous function called main that will execute the deployment process. Inside this function, the code first retrieves the deployer's address by getting a signer, which is an entity capable of signing transactions on the blockchain.

Once the deployer's address is obtained, the script proceeds to deploy the "HelloZeta" smart contract. It does so by first getting a contract factory for the "HelloZeta" contract using the ethers object. Then, it deploys the contract using the deploy method on the factory object, and waits for the deployment to complete. After the deployment is successful, the address of the deployed contract is logged to the console.

Deploy the contract to the ZetaChain testnet

Execute the following command to deploy HelloZeta contract to the athens testnet:

npx hardhat deploy --network athens

Deploying contracts with the account: 0x4bc06EAA43CA52BAaa857B21df6F49939a78274E
HelloZeta contract deployed to: 0xff4bB2F0F2F947320e1Aa09e14789E62cc429e9c