test: refactor test-net-reconnect-error

* var -> const/let
* assert.equal() -> assert.strictEqual()

PR-URL: #9903
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>

test/parallel/test-net-reconnect-error.js

@@ -1,13 +1,13 @@
 'use strict';
-var common = require('../common');
-var net = require('net');
-var assert = require('assert');
-var N = 20;
-var client_error_count = 0;
-var disconnect_count = 0;
+const common = require('../common');
+const net = require('net');
+const assert = require('assert');
+const N = 20;
+let client_error_count = 0;
+let disconnect_count = 0;
 
 // Hopefully nothing is running on common.PORT
-var c = net.createConnection(common.PORT);
+const c = net.createConnection(common.PORT);
 
 c.on('connect', function() {
   console.error('CLIENT connected');
@@ -17,7 +17,7 @@ c.on('connect', function() {
 c.on('error', function(e) {
   console.error('CLIENT error: ' + e.code);
   client_error_count++;
-  assert.equal('ECONNREFUSED', e.code);
+  assert.strictEqual('ECONNREFUSED', e.code);
 });
 
 c.on('close', function() {
@@ -27,6 +27,6 @@ c.on('close', function() {
 });
 
 process.on('exit', function() {
-  assert.equal(N + 1, disconnect_count);
-  assert.equal(N + 1, client_error_count);
+  assert.strictEqual(N + 1, disconnect_count);
+  assert.strictEqual(N + 1, client_error_count);
 });