stream: fix misleading error message

The method to implement is `_write` not `_transform`.

PR-URL: nodejs#18604
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

lib/_stream_writable.js

@@ -541,7 +541,7 @@ function clearBuffer(stream, state) {
 }
 
 Writable.prototype._write = function(chunk, encoding, cb) {
-  cb(new errors.Error('ERR_METHOD_NOT_IMPLEMENTED', '_transform'));
+  cb(new errors.Error('ERR_METHOD_NOT_IMPLEMENTED', '_write'));
 };
 
 Writable.prototype._writev = null;

test/parallel/test-stream-writable-constructor-set-methods.js

@@ -1,5 +1,5 @@
 'use strict';
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 
 const Writable = require('stream').Writable;
@@ -26,6 +26,16 @@ w2.write(Buffer.from('blerg'));
 w2.write(Buffer.from('blerg'));
 w2.end();
 
+const w3 = new Writable();
+
+w3.on('error', common.expectsError({
+  type: Error,
+  code: 'ERR_METHOD_NOT_IMPLEMENTED',
+  message: 'The _write method is not implemented'
+}));
+
+w3.end(Buffer.from('blerg'));
+
 process.on('exit', function() {
   assert.strictEqual(w._write, _write);
   assert(_writeCalled);