tty: enable buffering

HWM was set to 0 which would cause e.g. stdout.write(...) to
always return false.

Refs: nodejs#39246

PR-URL: nodejs#39253
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>

Author: ronag

lib/tty.js

@@ -57,7 +57,7 @@ function ReadStream(fd, options) {
   }
 
   net.Socket.call(this, {
-    highWaterMark: 0,
+    readableHighWaterMark: 0,
     handle: tty,
     manualStart: true,
     ...options
@@ -94,7 +94,7 @@ function WriteStream(fd) {
   }
 
   net.Socket.call(this, {
-    highWaterMark: 0,
+    readableHighWaterMark: 0,
     handle: tty,
     manualStart: true
   });

test/parallel/test-stdout-stderr-write.js

@@ -0,0 +1,8 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+
+// https://github.com/nodejs/node/pull/39246
+assert.strictEqual(process.stderr.write('asd'), true);
+assert.strictEqual(process.stdout.write('asd'), true);