Following an aging tutorial, I'm trying to learn how to test a smart contract:

const assert = require('assert');
const ganache = require('ganache-cli');
const Web3 = require('web3');

const web3 =  new Web3(ganache.provider());  
const { abi, bytecode} = require('../compile')

let accounts;
let simpleStorage;

beforeEach(async ()=>{
    // Get a list of all accounts
    accounts = await web3.eth.getAccounts();
    //Use one of those account to deply the contract
    simpleStorage = await new web3.eth.Contract(abi)
        data: bytecode,
        arguments: ['Hi there!'] 
        from: accounts[0],
        gas: '1000000'

describe('SimpleStorage', ()=> {
    it('deploy a contract', ()=>{

The compile.js is like:

const path = require('path');
const fs = require('fs');
const solc = require('solc');

const inboxpath = path.resolve(__dirname, 'contracts', 'Inbox.sol');
const source = fs.readFileSync(inboxpath, 'UTF-8');

var input = {
    language: 'Solidity',
    sources: {
        'Inbox.sol' : {
            content: source
    settings: {
        outputSelection: {
            '*': {
                '*': [ '*' ]

var output = JSON.parse(solc.compile(JSON.stringify(input)));

exports.abi = output.contracts['Inbox.sol']['SimpleStorage'].abi;
exports.bytecode = output.contracts['Inbox.sol']['SimpleStorage'].evm.bytecode.object;

And the contract Inbox.sol:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;

contract SimpleStorage {
    uint256 public num;

    function set(uint256 _num) public {
        num = _num;
    function get() public view returns (uint256) {
        return num;

But I get this error:

0 passing (290ms)
  1 failing

  1) "before each" hook for "deploy a contract":
     Uncaught Error: Callback was already called.
      at /home/pc/Desktop/inbox/node_modules/ganache-cli/build/webpack:/ganache/node_modules/ganache-core/node_modules/merkle-patricia-tree/node_modules/async/lib/async.js:43:1
      at d.<anonymous> (node_modules/ganache-cli/build/webpack:/ganache/node_modules/ganache-core/node_modules/merkle-patricia-tree/node_modules/async/lib/async.js:358:1)
      at d.emit (node:events:390:28)
      at d.destroy (node_modules/ganache-cli/build/webpack:/ganache/node_modules/ganache-core/node_modules/level-ws/level-ws.js:140:1)
      at finish (node:internal/streams/writable:763:14)
      at processTicksAndRejections (node:internal/process/task_queues:83:21)

    throw err;

Error: done() called multiple times in hook <"before each" hook for "deploy a contract"> (of root suite)
    at createMultipleDoneError (/home/pc/Desktop/inbox/node_modules/mocha/lib/errors.js:428:13)
    at multiple (/home/pc/Desktop/inbox/node_modules/mocha/lib/runnable.js:290:24)
    at done (/home/pc/Desktop/inbox/node_modules/mocha/lib/runnable.js:301:14)
    at /home/pc/Desktop/inbox/node_modules/mocha/lib/runnable.js:371:11
    at processTicksAndRejections (node:internal/process/task_queues:96:5) {
  valueType: 'undefined',
  value: undefined

version in package.json:

"ganache-cli": "^6.1.8",
"mocha": "^9.1.3",
"solc": "^0.8.11",
"web3": "^1.6.1"

This error bugs me for hours now. Appreciate your help to resolve it.

4 Answers 4


the only issue I see is, the callback for it should be async

describe('SimpleStorage', ()=> {
    it('deploy a contract',  async  ()=>{

One issue is that you pass a constructor argument (Hi there!), but your contract doesn't take any constructor arguments, so this should probably be an empty array.

Edit: Actually I cannot reproduce this locally. What is your environment (e.g. node version, OS) and how do you run your test? Do you by any chance have a repo to share?


try "ganache-cli": "^6.12.2"


Install the latest version 7.0.3 of ganache instead ganache-cli

npm install --save-dev ganache

in code just use

const ganache = require('ganache');
const web3 = new Web3(ganache.provider());

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