diff --git a/lib/tty.js b/lib/tty.js
index 144fc86b8e8205..2a62fcb859a244 100644
--- a/lib/tty.js
+++ b/lib/tty.js
@@ -29,9 +29,9 @@ const errnoException = util._errnoException;
 const errors = require('internal/errors');
 const readline = require('readline');
 
-exports.isatty = function(fd) {
+function isatty(fd) {
   return Number.isInteger(fd) && fd >= 0 && isTTY(fd);
-};
+}
 
 
 function ReadStream(fd, options) {
@@ -60,8 +60,6 @@ function ReadStream(fd, options) {
 }
 inherits(ReadStream, net.Socket);
 
-exports.ReadStream = ReadStream;
-
 ReadStream.prototype.setRawMode = function(flag) {
   flag = !!flag;
   this._handle.setRawMode(flag);
@@ -102,7 +100,6 @@ function WriteStream(fd) {
   }
 }
 inherits(WriteStream, net.Socket);
-exports.WriteStream = WriteStream;
 
 
 WriteStream.prototype.isTTY = true;
@@ -143,3 +140,6 @@ WriteStream.prototype.clearScreenDown = function() {
 WriteStream.prototype.getWindowSize = function() {
   return [this.columns, this.rows];
 };
+
+
+module.exports = { isatty, ReadStream, WriteStream };
diff --git a/test/pseudo-tty/test-tty-stream-constructors.js b/test/pseudo-tty/test-tty-stream-constructors.js
new file mode 100644
index 00000000000000..27c33bad1868d6
--- /dev/null
+++ b/test/pseudo-tty/test-tty-stream-constructors.js
@@ -0,0 +1,21 @@
+'use strict';
+require('../common');
+const assert = require('assert');
+const { ReadStream, WriteStream } = require('tty');
+
+{
+  // Verify that tty.ReadStream can be constructed without new.
+  const stream = ReadStream(0);
+
+  stream.unref();
+  assert(stream instanceof ReadStream);
+  assert.strictEqual(stream.isTTY, true);
+}
+
+{
+  // Verify that tty.WriteStream can be constructed without new.
+  const stream = WriteStream(1);
+
+  assert(stream instanceof WriteStream);
+  assert.strictEqual(stream.isTTY, true);
+}
diff --git a/test/pseudo-tty/test-tty-stream-constructors.out b/test/pseudo-tty/test-tty-stream-constructors.out
new file mode 100644
index 00000000000000..e69de29bb2d1d6
diff --git a/test/pseudo-tty/test-tty-window-size.js b/test/pseudo-tty/test-tty-window-size.js
new file mode 100644
index 00000000000000..782b66802e3ada
--- /dev/null
+++ b/test/pseudo-tty/test-tty-window-size.js
@@ -0,0 +1,85 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const { WriteStream } = require('tty');
+const { TTY } = process.binding('tty_wrap');
+const getWindowSize = TTY.prototype.getWindowSize;
+
+function monkeyPatchGetWindowSize(fn) {
+  TTY.prototype.getWindowSize = function() {
+    TTY.prototype.getWindowSize = getWindowSize;
+    return fn.apply(this, arguments);
+  };
+}
+
+{
+  // tty.WriteStream constructor does not define columns and rows if an error
+  // occurs while retrieving the window size from the handle.
+  monkeyPatchGetWindowSize(function() {
+    return -1;
+  });
+
+  const stream = WriteStream(1);
+
+  assert(stream instanceof WriteStream);
+  assert.strictEqual(stream.columns, undefined);
+  assert.strictEqual(stream.rows, undefined);
+}
+
+{
+  // _refreshSize() emits an error if an error occurs while retrieving the
+  // window size from the handle.
+  const stream = WriteStream(1);
+
+  stream.on('error', common.mustCall((err) => {
+    assert.strictEqual(err.syscall, 'getWindowSize');
+  }));
+
+  monkeyPatchGetWindowSize(function() {
+    return -1;
+  });
+
+  stream._refreshSize();
+}
+
+{
+  // _refreshSize() emits a 'resize' event when the window size changes.
+  monkeyPatchGetWindowSize(function(size) {
+    size[0] = 80;
+    size[1] = 24;
+    return 0;
+  });
+
+  const stream = WriteStream(1);
+
+  stream.on('resize', common.mustCall(() => {
+    assert.strictEqual(stream.columns, 82);
+    assert.strictEqual(stream.rows, 26);
+  }));
+
+  assert.strictEqual(stream.columns, 80);
+  assert.strictEqual(stream.rows, 24);
+
+  monkeyPatchGetWindowSize(function(size) {
+    size[0] = 82;
+    size[1] = 26;
+    return 0;
+  });
+
+  stream._refreshSize();
+}
+
+{
+  // WriteStream.prototype.getWindowSize() returns the current columns and rows.
+  monkeyPatchGetWindowSize(function(size) {
+    size[0] = 99;
+    size[1] = 32;
+    return 0;
+  });
+
+  const stream = WriteStream(1);
+
+  assert.strictEqual(stream.columns, 99);
+  assert.strictEqual(stream.rows, 32);
+  assert.deepStrictEqual(stream.getWindowSize(), [99, 32]);
+}
diff --git a/test/pseudo-tty/test-tty-window-size.out b/test/pseudo-tty/test-tty-window-size.out
new file mode 100644
index 00000000000000..e69de29bb2d1d6