diff --git a/testing/xvfb_unittest.py b/testing/xvfb_unittest.py
new file mode 100755
index 0000000..4aab40baa
--- /dev/null
+++ b/testing/xvfb_unittest.py
@@ -0,0 +1,108 @@
+#!/usr/bin/env python
+# Copyright (c) 2019 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Unit tests for xvfb.py functionality.
+
+Each unit test is launching xvfb_test_script.py
+through xvfb.py as a subprocess, then tests its expected output.
+"""
+
+import os
+import signal
+import subprocess
+import sys
+import time
+import unittest
+
+
+TEST_FILE = __file__.replace('.pyc', '.py')
+XVFB = TEST_FILE.replace('_unittest', '')
+XVFB_TEST_SCRIPT = TEST_FILE.replace('_unittest', '_test_script')
+
+
+def launch_process(args):
+  """Launches a sub process to run through xvfb.py."""
+  return subprocess.Popen(
+      [XVFB, XVFB_TEST_SCRIPT] + args, stdout=subprocess.PIPE,
+      stderr=subprocess.STDOUT, env=os.environ.copy())
+
+
+def read_subprocess_message(proc, starts_with):
+  """Finds the value after first line prefix condition."""
+  for line in proc.stdout:
+    if line.startswith(starts_with):
+      return line.rstrip().replace(starts_with, '')
+
+
+def send_signal(proc, sig, sleep_time=0.3):
+  """Sends a signal to subprocess."""
+  time.sleep(sleep_time)  # gives process time to launch.
+  os.kill(proc.pid, sig)
+  proc.wait()
+
+
+class XvfbLinuxTest(unittest.TestCase):
+
+  def setUp(self):
+    super(XvfbLinuxTest, self).setUp()
+    if sys.platform != 'linux2':
+      self.skipTest('linux only test')
+
+  def test_no_xvfb_display(self):
+    proc = launch_process(['--no-xvfb'])
+    proc.wait()
+    display = read_subprocess_message(proc, 'Display :')
+    self.assertEqual(display, os.environ.get('DISPLAY', 'None'))
+
+  def test_xvfb_display(self):
+    proc = launch_process([])
+    proc.wait()
+    display = read_subprocess_message(proc, 'Display :')
+    self.assertIsNotNone(display)
+    self.assertNotEqual(display, os.environ.get('DISPLAY', 'None'))
+
+  def test_no_xvfb_flag(self):
+    proc = launch_process(['--no-xvfb'])
+    proc.wait()
+    environ_flag = read_subprocess_message(proc, 'Inside_xvfb :')
+    self.assertEqual(environ_flag, 'None')
+
+  def test_xvfb_flag(self):
+    proc = launch_process([])
+    proc.wait()
+    environ_flag = read_subprocess_message(proc, 'Inside_xvfb :')
+    self.assertEqual(environ_flag, '1')
+
+  def test_xvfb_race_condition(self):
+    proc_list = [launch_process([]) for _ in range(15)]
+    for proc in proc_list:
+      proc.wait()
+    display_list = [read_subprocess_message(p, 'Display :') for p in proc_list]
+    for display in display_list:
+      self.assertIsNotNone(display)
+      self.assertNotEqual(display, os.environ.get('DISPLAY', 'None'))
+
+
+class XvfbTest(unittest.TestCase):
+
+  def setUp(self):
+    super(XvfbTest, self).setUp()
+    if sys.platform == 'win32':
+      self.skipTest('non-win32 test')
+
+  def test_send_sigint(self):
+    proc = launch_process(['--sleep'])
+    send_signal(proc, signal.SIGINT)
+    sig = read_subprocess_message(proc, 'Signal :')
+    self.assertEqual(sig, str(signal.SIGINT))
+
+  def test_send_sigterm(self):
+    proc = launch_process(['--sleep'])
+    send_signal(proc, signal.SIGTERM)
+    sig = read_subprocess_message(proc, 'Signal :')
+    self.assertEqual(sig, str(signal.SIGTERM))
+
+if __name__ == '__main__':
+  unittest.main()