Now that we’ve built the core logic for interacting with the Walnut contract, it’s time to tie everything together into a CLI that runs a multiplayer game session with two players - Alice and Bob. In this chapter, you’ll set up the environment variables for multiple players and write index.ts to simulate gameplay. Estimated time: ~20 minutes
Set Up Environment Variables
Before running the Walnut game, we need to define environment variables that store important configurations such as the RPC URL, chain ID, and player private keys.
• CHAIN_ID=31337 : 31337is the default chain ID for sanvil(your local Seismic node).
• RPC_URL=http://127.0.0.1:8545 : This is the RPC URL for interacting with the local Seismic node.
• ALICE_PRIVKEYand BOB_PRIVKEY : These are Alice and Bob’s private keys, allowing them to play the game. (These again are standard test keys provided by sanvil)
Write index.ts
Now, we’ll create the main entry point for our game session. This file will simulate gameplay, initializing players and having them interact with the Walnut contract. Open packages/cli/src/index.tsand follow these steps:
Import Dependencies
Import the required libraries to read environment variables, define network configurations, and interact with the Walnut contract.
import dotenv from 'dotenv'
import { join } from 'path'
import { seismicDevnet } from 'seismic-viem'
import { anvil } from 'viem/chains'
import { CONTRACT_DIR, CONTRACT_NAME } from '../lib/constants'
import { readContractABI, readContractAddress } from '../lib/utils'
import { App } from './app'
// Load environment variables from .env file
dotenv.config()
Define the main() function
This function initializes the contract and player wallets, then runs the game session.
async function main() {
if (!process.env.CHAIN_ID || !process.env.RPC_URL) {
console.error('Please set your environment variables.')
process.exit(1)
}
Read Contract Details
The contract’s ABI and deployed address are read from files generated during deployment.
console.log('=== Round 2 ===')
await app.reset('Bob')
await app.hit('Bob')
await app.shake('Bob', 1)
await app.hit('Bob')
await app.shake('Bob', 1)
await app.hit('Bob')
// Bob looks at the number in round 2
await app.look('Bob')
Alice Tries to Look in Round 2 (we expect this to fail since she has contributed in round 1 but not round 2)
// Alice tries to look in round 2, should fail by reverting
console.log('=== Testing Access Control ===')
console.log("Attempting Alice's look() in Bob's round (should revert)")
try {
await app.look('Alice')
console.error('❌ Expected look() to revert but it succeeded')
process.exit(1)
} catch (error) {
console.log('✅ Received expected revert')
}
}
Execute the main() function
This ensures that the script runs when executed.
main()
Running the CLI
Now, run the CLI from packages/cli by running:
bun dev
You should see something like this as the output:
=== Round 1 ===
- Player Alice writing shake()
- Player Alice writing hit()
- Player Alice writing shake()
- Player Alice writing hit()
- Player Alice writing shake()
- Player Alice writing hit()
- Player Alice reading look()
- Player Alice sees number: 7n
=== Round 2 ===
- Player Bob writing reset()
- Player Bob writing hit()
- Player Bob writing shake()
- Player Bob writing hit()
- Player Bob writing shake()
- Player Bob writing hit()
- Player Bob reading look()
- Player Bob sees number: 3n
=== Testing Access Control ===
- Attempting Alice's look() in Bob's round (should revert)
✅ Received expected revert
This output logs the events during two rounds of gameplay in the Walnut contract, showing interactions by Alice and Bob, along with a revert error when Alice attempts to call look()in Round 2.
