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, 15 insertions, 16 deletions

diff --git a/test/parallel/test-stream2-writable.js b/test/parallel/test-stream2-writable.js
index 2af3f683a2..712440368c 100644
--- a/test/parallel/test-stream2-writable.js
+++ b/test/parallel/test-stream2-writable.js
@@ -26,24 +26,23 @@ const W = require('_stream_writable');
 const D = require('_stream_duplex');
 const assert = require('assert');
 
-const util = require('util');
-util.inherits(TestWriter, W);
-
-function TestWriter() {
-  W.apply(this, arguments);
-  this.buffer = [];
-  this.written = 0;
+class TestWriter extends W {
+  constructor(opts) {
+    super(opts);
+    this.buffer = [];
+    this.written = 0;
+  }
+
+  _write(chunk, encoding, cb) {
+    // simulate a small unpredictable latency
+    setTimeout(() => {
+      this.buffer.push(chunk.toString());
+      this.written += chunk.length;
+      cb();
+    }, Math.floor(Math.random() * 10));
+  }
 }
 
-TestWriter.prototype._write = function(chunk, encoding, cb) {
-  // simulate a small unpredictable latency
-  setTimeout(function() {
-    this.buffer.push(chunk.toString());
-    this.written += chunk.length;
-    cb();
-  }.bind(this), Math.floor(Math.random() * 10));
-};
-
 const chunks = new Array(50);
 for (let i = 0; i < chunks.length; i++) {
   chunks[i] = 'x'.repeat(i);