node/test/parallel/test-net-error-twice.js

'use strict';
const common = require('../common');
const assert = require('assert');
const net = require('net');

const buf = Buffer.alloc(10 * 1024 * 1024, 0x62);

const errs = [];
let clientSocket;
let serverSocket;

function ready() {
  if (clientSocket && serverSocket) {
    clientSocket.destroy();
    serverSocket.write(buf);
  }
}

const srv = net.createServer(function onConnection(conn) {
  conn.on('error', function(err) {
    errs.push(err);
    if (errs.length > 1 && errs[0] === errs[1])
      common.fail('Should not emit the same error twice');
  });
  conn.on('close', function() {
    srv.unref();
  });
  serverSocket = conn;
  ready();
}).listen(0, function() {
  const client = net.connect({ port: this.address().port });

  client.on('connect', function() {
    clientSocket = client;
    ready();
  });
});

process.on('exit', function() {
  console.log(errs);
  assert.strictEqual(errs.length, 1);
});