What is causing the MaxListenersExceededWarning warning in web3js test code

Question

I've testing code for a contract in ethereum

const assert = require("assert");
const ganache = require("ganache-cli");
const Web3 = require("web3");
const web3 = new Web3(ganache.provider());
const { abi, evm } = require("../compile");

let accounts;
let inbox;
beforeEach(async () => {
  // Get a list of all accounts
  accounts = await web3.eth.getAccounts();

  // Use one of those accounts to deploy the contract
  inbox = await new web3.eth.Contract(abi)
    .deploy({
      data: evm.bytecode.object,
      arguments: ["Hi there!"]
    })
    .send({ from: accounts[0], gas: "1000000" });
});

describe("Inbox", () => {
  it("deploys a contract", () => {
    console.log(accounts);
    console.log(inbox);
    assert.ok(inbox.options.address);
  });
});

This is showing the following warning

(node:52888) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 data listeners added. Use emitter.setMaxListeners() to increase limit

What is the probable reason for this and how to resolve it?

Answer 1

Got the answer. It's an issue in web3js with send function for version 1.

So either set max listeners using

web3.currentProvider.setMaxListeners(300);

Or upgrade to v2^ it's fixed there .