Sei EVM Smart Contract Development with Foundry

Since Sei is an EVM compatible chain, existing EVM tooling like foundry forge or other could be re-used.

In this example we will be using foundry tooling .

Install the foundry tooling by following this Installation guide .

Create a new project following the Creating New Project Guide .

Also make sure you have a wallet on Sei network.

Once project is created, tweak the contract code to the following, by adding a getCounter function:


// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.22;
 
contract Counter {
    uint256 public number;
 
    function setNumber(uint256 newNumber) public {
        number = newNumber;
    }
 
    function increment() public {
        number++;
    }
 
    function getCount() public view returns (uint256) {
        return number;
    }
}

And the test code to the following:


// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.22;
 
import {Test, console} from "forge-std/Test.sol";
import {Counter} from "../src/Counter.sol";
 
contract CounterTest is Test {
    Counter public counter;
 
    function setUp() public {
        counter = new Counter();
        counter.setNumber(0);
    }
 
    function test_Increment() public {
        counter.increment();
        assertEq(counter.number(), 1);
    }
 
    function testFuzz_SetNumber(uint256 x) public {
        counter.setNumber(x);
        assertEq(counter.number(), x);
    }
 
    function test_GetCount() public {
        uint256 initialCount = counter.getCount();
        counter.increment();
        assertEq(counter.getCount(), initialCount + 1);
    }
}

Run the tests with the following command:


$ forge test

If tests pass, deploy the contract to the Sei chain with the following command:


$ forge create --rpc-url $SEI_NODE_URI --mnemonic $MNEMONIC src/Counter.sol:Counter --broadcast

Where $SEI_NODE_URI is the URI of the Sei node and $MNEMONIC is the mnemonic of the account that will deploy the contract. If you run local Sei node, the address will be http://localhost:8545 , otherwise you could grab a evm_rpc url from the registry . If deployment is successful, you will get the EVM contract address in the output.


[⠒] Compiling...
No files changed, compilation skipped
Deployer: $0X_DEPLOYER_ADDRESS
Deployed to: $0X_CONTRACT_ADDRESS
Transaction hash: $0X_TX_HASH

Let’s use the cast command to query the contract:


$ cast call $0X_CONTRACT_ADDRESS "getCount()(uint256)" --rpc-url $SEI_NODE_URI

The command should return 0 as the initial value of the counter.

Now we can use the cast command to call the increment function:


$ cast send $0X_CONTRACT_ADDRESS "increment()" --mnemonic $MNEMONIC --rpc-url $SEI_NODE_URI

If command is successful, you will get the transaction hash and other info back.

Now let’s call the getCount function again and this case it should return 1.


$ cast call $0X_CONTRACT_ADDRESS "getCount()(uint256)" --rpc-url $SEI_NODE_URI

Foundry generates the ABI for the contract in the out folder. You can use this ABI to interact with the contract from other tools like ethers.js or web3.js.

Calling contract using ethers.js

To call or query the contract from a frontend or a NodeJS script, you could use ethers.js like:


import { ethers } from 'ethers';
 
const privateKey = YOUR_PRIVATE_KEY;
const evmRpcEndpoint = YOUR_EVM_RPC_ENDPOINT;
const provider = new ethers.JsonRpcProvider(evmRpcEndpoint);
const signer = new ethers.Wallet(privateKey, provider);
 
if (!signer) {
    console.log('No signer found');
    return;
}
const abi = [
 {
      "type": "function",
      "name": "setNumber",
      "inputs": [
        {
          "name": "newNumber",
          "type": "uint256",
          "internalType": "uint256"
        }
      ],
      "outputs": [],
      "stateMutability": "nonpayable"
    },
    {
        "type": "function",
        "name": "getCount",
        "inputs": [],
        "outputs": [
            {
                "name": "",
                "type": "int256",
                "internalType": "int256"
            }
        ],
        "stateMutability": "view"
    },
    {
        "type": "function",
        "name": "increment",
        "inputs": [],
        "outputs": [],
        "stateMutability": "nonpayable"
    }
];
 
// Define the address of the deployed contract
const contractAddress = `0X_CONTRACT_ADDRESS`;
 
// Create a new instance of the ethers.js Contract object
const contract = new ethers.Contract(contractAddress, abi, signer);
 
// Call the contract's functions
async function getCount() {
    const count = await contract.getCount();
    console.log(count.toString());
}
 
async function increment() {
    const txResponse = await contract.increment();
    const mintedTx = await txResponse.wait();
    console.log(mintedTx);
}
 
await increment();
await getCount();