test: use mustNotCall() in test-stream2-objects

Use `common.mustNotCall()` in test-stream2-objects.js to confirm that
noop function is never invoked.
PR-URL: #13249
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: Trott

test/parallel/test-stream2-objects.js

@@ -1,5 +1,5 @@
 'use strict';
-require('../common');
+constcommon=require('../common');
 constReadable=require('_stream_readable');
 constWritable=require('_stream_writable');
 constassert=require('assert');
@@ -54,7 +54,7 @@ function toArray(callback) {
 
 functionfromArray(list){
 constr=newReadable({objectMode: true});
-r._read=noop;
+r._read=common.mustNotCall();
 list.forEach(function(chunk){
 r.push(chunk);
 });
@@ -63,8 +63,6 @@ function fromArray(list) {
 returnr;
 }
 
-functionnoop(){}
-
 test('can read objects from stream',function(t){
 constr=fromArray([{one: '1'},{two: '2'}]);
 
@@ -144,7 +142,7 @@ test('can read strings as objects', function(t) {
 constr=newReadable({
 objectMode: true
 });
-r._read=noop;
+r._read=common.mustNotCall();
 constlist=['one','two','three'];
 list.forEach(function(str){
 r.push(str);
@@ -162,7 +160,7 @@ test('read(0) for object streams', function(t) {
 constr=newReadable({
 objectMode: true
 });
-r._read=noop;
+r._read=common.mustNotCall();
 
 r.push('foobar');
 r.push(null);
@@ -178,7 +176,7 @@ test('falsey values', function(t) {
 constr=newReadable({
 objectMode: true
 });
-r._read=noop;
+r._read=common.mustNotCall();
 
 r.push(false);
 r.push(0);
@@ -229,7 +227,7 @@ test('high watermark push', function(t) {
 highWaterMark: 6,
 objectMode: true
 });
-r._read=function(n){};
+r._read=common.mustNotCall();
 for(leti=0;i<6;i++){
 constbool=r.push(i);
 assert.strictEqual(bool,i!==5);