test: use ES6 classes instead of util.inherits

PR-URL: https://github.com/nodejs/node/pull/16938
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>

1 files changed, 13 insertions, 18 deletions

diff --git a/test/parallel/test-stream-big-packet.js b/test/parallel/test-stream-big-packet.js
index 8575c3e43a..18b9b7ee4f 100644
--- a/test/parallel/test-stream-big-packet.js
+++ b/test/parallel/test-stream-big-packet.js
@@ -22,31 +22,26 @@
 'use strict';
 require('../common');
 const assert = require('assert');
-const util = require('util');
 const stream = require('stream');
 
 let passed = false;
 
-function PassThrough() {
-  stream.Transform.call(this);
+class PassThrough extends stream.Transform {
+  _transform(chunk, encoding, done) {
+    this.push(chunk);
+    done();
+  }
 }
-util.inherits(PassThrough, stream.Transform);
-PassThrough.prototype._transform = function(chunk, encoding, done) {
-  this.push(chunk);
-  done();
-};
 
-function TestStream() {
-  stream.Transform.call(this);
-}
-util.inherits(TestStream, stream.Transform);
-TestStream.prototype._transform = function(chunk, encoding, done) {
-  if (!passed) {
-    // Char 'a' only exists in the last write
-    passed = chunk.toString().includes('a');
+class TestStream extends stream.Transform {
+  _transform(chunk, encoding, done) {
+    if (!passed) {
+      // Char 'a' only exists in the last write
+      passed = chunk.toString().includes('a');
+    }
+    done();
   }
-  done();
-};
+}
 
 const s1 = new PassThrough();
 const s2 = new PassThrough();