Truffle with the Zen EVM sidechain

Setup

Installation

First of all it’s required to install the framework itself.

npm install -g truffle

If any problem, please refer to the Truffle installation guide.

Initialize a new Truffle project

This will create the basic directory structure of a Truffle project in a new folder.

mkdir truffle-project
cd truffle-project
truffle init
npm init -y

Edit configuration to support ZEN network

In the truffle-config.js file, add into the "networks" section the following code:

{
  ...
  networks: {
    zen: {
      provider: () => new HDWalletProvider({
        mnemonic: "word1 ... word12",
        providerOrUrl: "https://evm-tn-m2.horizenlabs.io/ethv1"
      }),
      network_id: 1661,
      production: false
    }
  }
  ...
}

Replacing the "word1 ... word12" with the mnemonic phrase for a valid Wallet. Please, note that network_id is different depending on the environment you are using.

Also uncomment the line:

const HDWalletProvider = require('@truffle/hdwallet-provider');

and install it via NPM: npm install @truffle/hdwallet-provider.

Usage

Get basic information

Using truffle console --network zen you can enter an interactive JavaScript console which comes preconfigured with Truffle and the configuration already setup. This way you can get information like the current block height, the chainId and much more:

truffle(zen)> web3.eth.getBlockNumber()
2976
truffle(zen)> web3.eth.getChainId()
1661

Deploy a contract

Deploying a standard ERC20 contract based on the implementation by OpenZeppelin can be done with the following steps:

• install the openzeppelin contracts via NPM: npm install @openzeppelin/contracts
• create a new contract in the contracts folder, see contracts/DemoERC20.sol
• add a deployment script in the migrations folder, see migrations/1_deploy_DemoToken.js
• execute the script: truffle migrate --network zen

Example output

> truffle migrate --network zen

Compiling your contracts...
===========================
> Compiling ./contracts/DemoToken.sol
> Compiling @openzeppelin/contracts/token/ERC20/ERC20.sol
> Compiling @openzeppelin/contracts/token/ERC20/IERC20.sol
> Compiling @openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol
> Compiling @openzeppelin/contracts/utils/Context.sol
> Artifacts written to /home/gigo/code/zen-sidechain-truffle/build/contracts
> Compiled successfully using:
   - solc: 0.8.17+commit.8df45f5f.Emscripten.clang


Starting migrations...
======================
> Network name:    'zen'
> Network id:      1661
> Block gas limit: 30000000 (0x1c9c380)


1_deploy_DemoToken.js
=====================

   Deploying 'DemoToken'
   ---------------------
   > transaction hash:    0x41063db41456727a863e33670450cdb8b8bd87e5e25decf76b551e5b6b88110f
   > Blocks: 0            Seconds: 188
   > contract address:    0x3aeFC08E17f681155396D061FBf1Aa622823122b
   > block number:        3624
   > block timestamp:     1666287964
   > account:             0x7507Cebb915af00019be3a5FE8897b2eE115B166
   > balance:             0.397071852433176985
   > gas used:            1171259 (0x11df3b)
   > gas price:           2.500000007 gwei
   > value sent:          0 ETH
   > total cost:          0.002928147508198813 ETH

   > Saving artifacts
   -------------------------------------
   > Total cost:     0.002928147508198813 ETH

Summary
=======
> Total deployments:   1
> Final cost:          0.002928147508198813 ETH

Interacting with the contract

Using the Truffle console interacting with the deployed contract becomes very convenient:

> truffle console --network zen
truffle(zen)> const contract = await DemoToken.deployed()
truffle(zen)> contract.name()
'Demo Token'
truffle(zen)> contract.symbol()
'DEMO'
truffle(zen)> const myAccounts = await web3.eth.getAccounts()
undefined
truffle(zen)> myAccounts
[ '0x7507Cebb915af00019be3a5FE8897b2eE115B166' ]
truffle(zen)> contract.balanceOf(myAccounts[0])
BN {
  negative: 0,
  words: [ 100, <1 empty item> ],
  length: 1,
  red: null
}
truffle(zen)> contract.transfer("0x03f14683E2f95883815f0df3C9145Efe24575163", 12)
{
  tx: '0xa19ffcb54152804ed10c778828215d505656d7a112921f11e7c9ffb47c749341',
  receipt: ...,
  logs: ...
}
truffle(zen)> contract.balanceOf(myAccounts[0])
BN { negative: 0, words: [ 88, <1 empty item> ], length: 1, red: null }

EOA to EOA transfer

truffle(zen)> web3.eth.sendTransaction({ from: myAccounts[0], to: "0x03f14683E2f95883815f0df3C9145Efe24575163", value: 100 })
{
  type: '0x02',
  transactionHash: '0x8577a509da611abb479bed415677e04c7083d75d96b45f4f38ad794f8b2a0799',
  transactionIndex: 0,
  blockHash: '0x14c0a80f8d913e0433d69af367d249c4f431935911df51201e6a77aa31860a57',
  blockNumber: 3633,
  from: '0x7507cebb915af00019be3a5fe8897b2ee115b166',
  to: '0x03f14683e2f95883815f0df3c9145efe24575163',
  cumulativeGasUsed: 21000,
  gasUsed: 21000,
  logs: [],
  logsBloom: '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000',
  status: true,
  effectiveGasPrice: 2500000007
}

Interacting with native smart contracts

The easiest way to access the native smart contracts with Truffle is using the Solidity interfaces:

• contracts/ForgerStakes.sol
• contracts/WithdrawalRequests.sol

Submit withdrawal request

Here we send some Zen to the submitWithdrawalRequest on the native contract for Withdrawal Requests. Note the mcAddress variable, which will be the address on the Zen mainchain the Zen will be withdrawn to.

truffle compile
truffle console --network zen
truffle(zen)> const withdrawalContract = await WithdrawalRequests.at("0x0000000000000000000011111111111111111111")
undefined
truffle(zen)> const mcAddress = "0x0000000000000000000000000000000000001234"
truffle(zen)> withdrawalContract.submitWithdrawalRequest("0x0000000000000000000000000000000000001234", { value: 1000000000000 })
{
  tx: '0x07d1efe3e4cba65ae9049a456650960c6a8b8dd547c71a8db751d0deac9dd86d',
  receipt: {
    type: '0x02',
    transactionHash: '0x07d1efe3e4cba65ae9049a456650960c6a8b8dd547c71a8db751d0deac9dd86d',
    transactionIndex: 0,
    blockHash: '0xdfca20a6aeb95d43fd9d813e70ca5d9ee54bda0e96fb8a22e7d6932ddc518d14',
    blockNumber: 3637,
    from: '0x7507cebb915af00019be3a5fe8897b2ee115b166',
    to: '0x0000000000000000000011111111111111111111',
    cumulativeGasUsed: 24167,
    gasUsed: 24167,
    logs: [],
    logsBloom: '0x01000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000400000000000000000010000000000000008000000000000000000000000000000000000000000000000000000000000000000000000000000000000000080000008000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000001000000000000008000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000001000000000000000000000',
    status: true,
    effectiveGasPrice: 2500000007,
    rawLogs: [ [Object] ]
  },
  logs: []
}