This directory contains an example on how to run smart contracts written in Solidity.

The example does these things:

1. Compiles the contract `contracts/Greeter.sol`

1. Instantiates a VM

1. Creates an account

1. Funds the account with 1 ETH

1. Deploys the Greeter contract

1. Calls a constant function

1. Sends a transaction to the contract, modifying its state

1. Calls a constant function to verify the state change

To install this example you should

1. Run `npm install` in the root of this project

1. Run `npm install` in this directory

1. Run `npm run build:dist` in the root of this project

1. Run `npm run example` in this directory

pragma solidity ^0.5.10;

contract Greeter {

string greeting;

constructor(string memory _greeting) public {

greeting = _greeting;

}

function setGreeting(string memory _greeting) public {

greeting = _greeting;

}

function greet() public view returns (string memory) {

return greeting;

}

}

import VM from '../../dist'

import * as assert from 'assert'

import * as path from 'path'

import * as fs from 'fs'

import { promisify } from 'util'

import * as util from 'ethereumjs-util'

import Account from 'ethereumjs-account'

const Transaction = require('ethereumjs-tx') // Change when https://github.com/ethereumjs/ethereumjs-vm/pull/541 gets merged

const abi = require('ethereumjs-abi')

const solc = require('solc')

const INITIAL_GREETING = 'Hello, World!'

const SECOND_GREETING = 'Hola, Mundo!'

function getSolcInput() {

return {

language: 'Solidity',

sources: {

'contracts/Greeter.sol': {

content: fs.readFileSync(path.join(__dirname, 'contracts', 'Greeter.sol'), 'utf8'),

},

// If more contracts were to be compiled, they should have their own entries here

},

settings: {

optimizer: {

enabled: true,

runs: 200,

},

evmVersion: 'petersburg',

outputSelection: {

'*': {

'*': ['abi', 'evm.bytecode'],

},

},

},

}

function compileContracts() {

const input = getSolcInput()

const output = JSON.parse(solc.compile(JSON.stringify(input)))

let compilationFailed = false

if (output.errors) {

for (const error of output.errors) {

if (error.severity === 'error') {

console.error(error.formattedMessage)

compilationFailed = true

} else {

console.warn(error.formattedMessage)

}

}

}

if (compilationFailed) {

return undefined

}

return output

function getGreeterDeploymentBytecode(solcOutput: any): any {

return solcOutput.contracts['contracts/Greeter.sol'].Greeter.evm.bytecode.object

async function getAccountNonce(vm: VM, accountPrivateKey: Buffer) {

const account = (await promisify(vm.stateManager.getAccount.bind(vm.stateManager))(

util.privateToAddress(accountPrivateKey),

)) as Account

return account.nonce

async function deployContract(

vm: VM,

senderPrivateKey: Buffer,

deploymentBytecode: Buffer,

greeting: string,

): Promise<Buffer> {

// Contracts are deployed by sending their deployment bytecode to the address 0

// The contract params should be abi-encoded and appended to the deployment bytecode.

const params = abi.rawEncode(['string'], [greeting])

const tx = new Transaction({

to: null,

value: 0,

gas: 2000000, // We assume that 2M is enough,

gasPrice: 1,

data: '0x' + deploymentBytecode + params.toString('hex'),

nonce: await getAccountNonce(vm, senderPrivateKey),

})

tx.sign(senderPrivateKey)

const deploymentResult = await vm.runTx({ tx })

if (deploymentResult.vm.exception === 0) {

throw deploymentResult.vm.exceptionError

}

return deploymentResult.createdAddress!

async function setGreeting(

vm: VM,

senderPrivateKey: Buffer,

contractAddress: Buffer,

greeting: string,

) {

const params = abi.rawEncode(['string'], [greeting])

const tx = new Transaction({

to: contractAddress,

value: 0,

gas: 2000000, // We assume that 2M is enough,

gasPrice: 1,

data: '0x' + abi.methodID('setGreeting', ['string']).toString('hex') + params.toString('hex'),

nonce: await getAccountNonce(vm, senderPrivateKey),

})

tx.sign(senderPrivateKey)

const setGreetingResult = await vm.runTx({ tx })

if (setGreetingResult.vm.exception === 0) {

throw setGreetingResult.vm.exceptionError

}

async function getGreeting(vm: VM, contractAddress: Buffer, caller: Buffer) {

const greetResult = await vm.runCall({

to: contractAddress,

caller: caller,

origin: caller, // The tx.origin is also the caller here

data: abi.methodID('greet', []),

})

if (greetResult.vm.exception === 0) {

throw greetResult.vm.exceptionError

}

const results = abi.rawDecode(['string'], greetResult.vm.return)

return results[0]

async function main() {

const accountPk = new Buffer(

'e331b6d69882b4cb4ea581d88e0b604039a3de5967688d3dcffdd2270c0fd109',

'hex',

)

const accountAddress = util.privateToAddress(accountPk)

console.log('Account:', util.bufferToHex(accountAddress))

const account = new Account({ balance: 1e18 })

const vm = new VM()

await promisify(vm.stateManager.putAccount.bind(vm.stateManager))(accountAddress, account)

console.log('Set account a balance of 1 ETH')

console.log('Compiling...')

const solcOutput = compileContracts()

if (solcOutput === undefined) {

throw new Error('Compilation failed')

} else {

console.log('Compiled the contract')

}

const bytecode = getGreeterDeploymentBytecode(solcOutput)

console.log('Deploying the contract...')

const contractAddress = await deployContract(vm, accountPk, bytecode, INITIAL_GREETING)

console.log('Contract address:', util.bufferToHex(contractAddress))

const greeting = await getGreeting(vm, contractAddress, accountAddress)

console.log('Greeting:', greeting)

assert.equal(greeting, INITIAL_GREETING)

console.log('Changing greeting...')

await setGreeting(vm, accountPk, contractAddress, SECOND_GREETING)

const greeting2 = await getGreeting(vm, contractAddress, accountAddress)

console.log('Greeting:', greeting2)

assert.equal(greeting2, SECOND_GREETING)

console.log('Everything run correctly!')

.then(() => process.exit(0))

.catch(err => {

console.error(err)

process.exit(1)

})

{

"name": "run-solidity-contract",

"main": "index.js",

"scripts": {

"example": "ts-node index.ts"

},

"dependencies": {

"ethereumjs-abi": "^0.6.7",

"solc": "^0.5.10"

}

}