test: use ES6 classes instead of util.inherits

PR-URL: #16938
Backport-PR-URL: #16946
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>

test/parallel/test-crypto-lazy-transform-writable.js

@@ -7,7 +7,6 @@ if (!common.hasCrypto)
 const assert = require('assert');
 const crypto = require('crypto');
 const Stream = require('stream');
-const util = require('util');
 
 const hasher1 = crypto.createHash('sha256');
 const hasher2 = crypto.createHash('sha256');
@@ -18,12 +17,12 @@ hasher1.end();
 
 const expected = hasher1.read().toString('hex');
 
-function OldStream() {
-  Stream.call(this);
-
-  this.readable = true;
+class OldStream extends Stream {
+  constructor() {
+    super();
+    this.readable = true;
+  }
 }
-util.inherits(OldStream, Stream);
 
 const stream = new OldStream();
 

test/parallel/test-crypto-stream.js

@@ -26,26 +26,26 @@ if (!common.hasCrypto)
 
 const assert = require('assert');
 const stream = require('stream');
-const util = require('util');
 const crypto = require('crypto');
 
-// Small stream to buffer converter
-function Stream2buffer(callback) {
-  stream.Writable.call(this);
+if (!common.hasFipsCrypto) {
+  // Small stream to buffer converter
+  class Stream2buffer extends stream.Writable {
+    constructor(callback) {
+      super();
 
-  this._buffers = [];
-  this.once('finish', function() {
-    callback(null, Buffer.concat(this._buffers));
-  });
-}
-util.inherits(Stream2buffer, stream.Writable);
+      this._buffers = [];
+      this.once('finish', function() {
+        callback(null, Buffer.concat(this._buffers));
+      });
+    }
 
-Stream2buffer.prototype._write = function(data, encodeing, done) {
-  this._buffers.push(data);
-  return done(null);
-};
+    _write(data, encodeing, done) {
+      this._buffers.push(data);
+      return done(null);
+    }
+  }
 
-if (!common.hasFipsCrypto) {
   // Create an md5 hash of "Hallo world"
   const hasher1 = crypto.createHash('md5');
   hasher1.pipe(new Stream2buffer(common.mustCall(function end(err, hash) {

test/parallel/test-event-emitter-listeners.js

@@ -24,12 +24,9 @@
 require('../common');
 const assert = require('assert');
 const events = require('events');
-const util = require('util');
 
 function listener() {}
 function listener2() {}
-class TestStream { constructor() { } }
-util.inherits(TestStream, events.EventEmitter);
 
 {
   const ee = new events.EventEmitter();
@@ -81,6 +78,7 @@ util.inherits(TestStream, events.EventEmitter);
 }
 
 {
+  class TestStream extends events.EventEmitter {}
   const s = new TestStream();
   assert.deepStrictEqual(s.listeners('foo'), []);
 }

test/parallel/test-http-client-read-in-error.js

@@ -2,38 +2,34 @@
 require('../common');
 const net = require('net');
 const http = require('http');
-const util = require('util');
 
-function Agent() {
-  http.Agent.call(this);
-}
-util.inherits(Agent, http.Agent);
-
-Agent.prototype.createConnection = function() {
-  const self = this;
-  const socket = new net.Socket();
+class Agent extends http.Agent {
+  createConnection() {
+    const socket = new net.Socket();
 
-  socket.on('error', function() {
-    socket.push('HTTP/1.1 200\r\n\r\n');
-  });
+    socket.on('error', function() {
+      socket.push('HTTP/1.1 200\r\n\r\n');
+    });
 
-  socket.on('newListener', function onNewListener(name) {
-    if (name !== 'error')
-      return;
-    socket.removeListener('newListener', onNewListener);
+    let onNewListener;
+    socket.on('newListener', onNewListener = (name) => {
+      if (name !== 'error')
+        return;
+      socket.removeListener('newListener', onNewListener);
 
-    // Let other listeners to be set up too
-    process.nextTick(function() {
-      self.breakSocket(socket);
+      // Let other listeners to be set up too
+      process.nextTick(() => {
+        this.breakSocket(socket);
+      });
     });
-  });
 
-  return socket;
-};
+    return socket;
+  }
 
-Agent.prototype.breakSocket = function breakSocket(socket) {
-  socket.emit('error', new Error('Intentional error'));
-};
+  breakSocket(socket) {
+    socket.emit('error', new Error('Intentional error'));
+  }
+}
 
 const agent = new Agent();
 

test/parallel/test-http-client-readable.js

@@ -23,41 +23,37 @@
 const common = require('../common');
 const assert = require('assert');
 const http = require('http');
-const util = require('util');
 
 const Duplex = require('stream').Duplex;
 
-function FakeAgent() {
-  http.Agent.call(this);
-}
-util.inherits(FakeAgent, http.Agent);
-
-FakeAgent.prototype.createConnection = function() {
-  const s = new Duplex();
-  let once = false;
+class FakeAgent extends http.Agent {
+  createConnection() {
+    const s = new Duplex();
+    let once = false;
 
-  s._read = function() {
-    if (once)
-      return this.push(null);
-    once = true;
+    s._read = function() {
+      if (once)
+        return this.push(null);
+      once = true;
 
-    this.push('HTTP/1.1 200 Ok\r\nTransfer-Encoding: chunked\r\n\r\n');
-    this.push('b\r\nhello world\r\n');
-    this.readable = false;
-    this.push('0\r\n\r\n');
-  };
+      this.push('HTTP/1.1 200 Ok\r\nTransfer-Encoding: chunked\r\n\r\n');
+      this.push('b\r\nhello world\r\n');
+      this.readable = false;
+      this.push('0\r\n\r\n');
+    };
 
-  // Blackhole
-  s._write = function(data, enc, cb) {
-    cb();
-  };
+    // Blackhole
+    s._write = function(data, enc, cb) {
+      cb();
+    };
 
-  s.destroy = s.destroySoon = function() {
-    this.writable = false;
-  };
+    s.destroy = s.destroySoon = function() {
+      this.writable = false;
+    };
 
-  return s;
-};
+    return s;
+  }
+}
 
 let received = '';
 

test/parallel/test-pipe-outgoing-message-data-emitted-after-ended.js

@@ -2,17 +2,13 @@
 const common = require('../common');
 const http = require('http');
 const assert = require('assert');
-const util = require('util');
 const stream = require('stream');
 
 // Verify that when piping a stream to an `OutgoingMessage` (or a type that
 // inherits from `OutgoingMessage`), if data is emitted after the
 // `OutgoingMessage` was closed - a `write after end` error is raised
 
-function MyStream() {
-  stream.call(this);
-}
-util.inherits(MyStream, stream);
+class MyStream extends stream {}
 
 const server = http.createServer(common.mustCall(function(req, res) {
   const myStream = new MyStream();

test/parallel/test-readline-interface.js

@@ -27,17 +27,14 @@ const assert = require('assert');
 const readline = require('readline');
 const internalReadline = require('internal/readline');
 const EventEmitter = require('events').EventEmitter;
-const inherits = require('util').inherits;
 const { Writable, Readable } = require('stream');
 
-function FakeInput() {
-  EventEmitter.call(this);
+class FakeInput extends EventEmitter {
+  resume() {}
+  pause() {}
+  write() {}
+  end() {}
 }
-inherits(FakeInput, EventEmitter);
-FakeInput.prototype.resume = () => {};
-FakeInput.prototype.pause = () => {};
-FakeInput.prototype.write = () => {};
-FakeInput.prototype.end = () => {};
 
 function isWarned(emitter) {
   for (const name in emitter) {

test/parallel/test-readline-keys.js

@@ -2,14 +2,9 @@
 const common = require('../common');
 const PassThrough = require('stream').PassThrough;
 const assert = require('assert');
-const inherits = require('util').inherits;
 const Interface = require('readline').Interface;
 
-
-function FakeInput() {
-  PassThrough.call(this);
-}
-inherits(FakeInput, PassThrough);
+class FakeInput extends PassThrough {}
 
 function extend(k) {
   return Object.assign({ ctrl: false, meta: false, shift: false }, k);

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();

test/parallel/test-stream-events-prepend.js

@@ -1,26 +1,23 @@
 'use strict';
 const common = require('../common');
 const stream = require('stream');
-const util = require('util');
 
-function Writable() {
-  this.writable = true;
-  stream.Writable.call(this);
-  this.prependListener = undefined;
+class Writable extends stream.Writable {
+  constructor() {
+    super();
+    this.prependListener = undefined;
+  }
+
+  _write(chunk, end, cb) {
+    cb();
+  }
 }
-util.inherits(Writable, stream.Writable);
-Writable.prototype._write = function(chunk, end, cb) {
-  cb();
-};
 
-function Readable() {
-  this.readable = true;
-  stream.Readable.call(this);
+class Readable extends stream.Readable {
+  _read() {
+    this.push(null);
+  }
 }
-util.inherits(Readable, stream.Readable);
-Readable.prototype._read = function() {
-  this.push(null);
-};
 
 const w = new Writable();
 w.on('pipe', common.mustCall());