diff --git a/au_test_harness/au_test.py b/au_test_harness/au_test.py
index a4c5758..c0f0de1 100644
--- a/au_test_harness/au_test.py
+++ b/au_test_harness/au_test.py
@@ -4,6 +4,8 @@
 
 """Module containing a test suite that is run to test auto updates."""
 
+from __future__ import print_function
+
 import os
 import re
 import time
@@ -71,7 +73,7 @@
         port_in=proxy_port,
         address_out='127.0.0.1',
         port_out=dev_server_wrapper.DEFAULT_PORT,
-        filter=update_filter
+        data_filter=update_filter
     )
     proxy.serve_forever_in_thread()
     try:
@@ -149,6 +151,7 @@
       def __init__(self):
         """Defines variable shared across all connections."""
         self.close_count = 0
+        self.data_size = 0
 
       def setup(self):
         """Called once at the start of each connection."""
@@ -212,6 +215,10 @@
       It does this by inserting 3 20 second delays when transmitting
       data after 2M has been sent.
       """
+      def __init__(self):
+        """Defines variable shared across all connections."""
+        self.data_size = 0
+        self.delay_count = 0
 
       def setup(self):
         """Called once at the start of each connection."""
diff --git a/au_test_harness/au_worker.py b/au_test_harness/au_worker.py
index 88ec805..4b3417a 100644
--- a/au_test_harness/au_worker.py
+++ b/au_test_harness/au_worker.py
@@ -9,13 +9,14 @@
 various types of target.  Types of targets include VM's, real devices, etc.
 """
 
+from __future__ import print_function
+
 import inspect
 import os
 
 from chromite.lib import cros_build_lib
 from chromite.lib import cros_logging as logging
 from chromite.lib import dev_server_wrapper
-from chromite.lib import path_util
 from crostestutils.au_test_harness import update_exception
 
 
@@ -41,6 +42,16 @@
       self.verify_suite = 'suite:%s' % (options.verify_suite_name or 'smoke')
     self.ssh_private_key = options.ssh_private_key
 
+    # Attributes to be initialized in Initialize.
+    self._ssh_port = None
+    self._kvm_pid_file = None
+
+    # Initialize test results directory.
+    self.test_name = None
+    self.all_results_directory = None
+    self.fail_results_directory = None
+    self.results_count = 0
+
   def CleanUp(self):
     """Called at the end of every test."""
 
@@ -52,8 +63,10 @@
     else:
       msg = 'Performing a full update to %s' % update_target
 
-    if from_vm: msg += ' in a VM'
-    if proxy: msg += ' using a proxy on port ' + str(proxy)
+    if from_vm:
+      msg += ' in a VM'
+    if proxy:
+      msg += ' using a proxy on port ' + str(proxy)
     return msg
 
   def PrepareBase(self, image_path, signed_base):
@@ -74,10 +87,7 @@
     """Implementation of an actual update.
 
     Subclasses must override this method with the correct update procedure for
-    the class.
-
-    Args:
-      See PerformUpdate for description of args.
+    the class. See PerformUpdate for args.
     """
 
   def UpdateUsingPayload(self, update_path, stateful_change='old',
@@ -88,11 +98,11 @@
     the class.
 
     Args:
-      update_path:  Path to the image to update with. This directory should
-        contain both update.gz, and stateful.image.gz
+      update_path: Path to the image to update with. This directory should
+          contain both update.gz, and stateful.image.gz
       stateful_change: How to perform the stateful update.
-      proxy_port:  Port to have the client connect to. For use with
-        CrosTestProxy.
+      proxy_port: Port to have the client connect to. For use with
+          CrosTestProxy.
     """
 
   def VerifyImage(self, unittest, percent_required_to_pass=100, test=''):
@@ -102,11 +112,11 @@
     override this method with the correct update procedure for the class.
 
     Args:
-      unittest: pointer to a unittest to fail if we cannot verify the image.
-      percent_required_to_pass:  percentage required to pass.  This should be
-        fall between 0-100.
-      test: test that will be used to verify the image. If omitted or equal to
-        the empty string the code will use self.verify_suite.
+      unittest: Pointer to a unittest to fail if we cannot verify the image.
+      percent_required_to_pass: Percentage required to pass.  This should be
+          fall between 0-100.
+      test: Test that will be used to verify the image. If omitted or equal to
+          the empty string the code will use self.verify_suite.
 
     Returns:
       Returns the percent that passed.
@@ -122,20 +132,21 @@
     instead.
 
     Args:
-      image_path:  Path to the image to update with.  This image must be a test
-        image.
-      src_image_path:  Optional.  If set, perform a delta update using the
-        image specified by the path as the source image.
+      image_path: Path to the image to update with.  This image must be a test
+          image.
+      src_image_path: Optional.  If set, perform a delta update using the
+          image specified by the path as the source image.
       stateful_change: How to modify the stateful partition.  Values are:
-          'old':  Don't modify stateful partition.  Just update normally.
-          'clean':  Uses clobber-state to wipe the stateful partition with the
-            exception of code needed for ssh.
-      proxy_port:  Port to have the client connect to. For use with
-        CrosTestProxy.
+          'old': Don't modify stateful partition.  Just update normally.
+          'clean': Uses clobber-state to wipe the stateful partition with the
+              exception of code needed for ssh.
+      proxy_port: Port to have the client connect to. For use with
+          CrosTestProxy.
       payload_signing_key: Path to the private key to use to sign payloads.
     Raises an update_exception.UpdateException if _UpdateImage returns an error.
     """
-    if not self.use_delta_updates: src_image_path = ''
+    if not self.use_delta_updates:
+      src_image_path = ''
     key_to_use = payload_signing_key
 
     self.UpdateImage(image_path, src_image_path, stateful_change, proxy_port,
@@ -184,11 +195,16 @@
     Modifies cmd in places by appending appropriate items given args.
 
     Args:
-      See PerformUpdate for description of args.
+      cmd: See PerformUpdate.
+      image_path: See PerformUpdate.
+      src_image_path: See PerformUpdate.
+      proxy_port: See PerformUpdate.
+      payload_signing_key: See PerformUpdate.
       for_vm: Additional optional argument to say that the payload is intended
-        for vm usage (so we don't patch the kernel).
+          for vm usage (so we don't patch the kernel).
     """
-    if proxy_port: cmd.append('--proxy_port=%s' % proxy_port)
+    if proxy_port:
+      cmd.append('--proxy_port=%s' % proxy_port)
     update_id = dev_server_wrapper.GenerateUpdateId(
         image_path, src_image_path, payload_signing_key,
         for_vm=for_vm)
@@ -204,11 +220,12 @@
   def RunUpdateCmd(self, cmd, log_directory=None):
     """Runs the given update cmd given verbose options.
 
-    Raises an update_exception.UpdateException if the update fails.
-
     Args:
-      cmd:  The shell cmd to run.
-      log_directory:  Where to store the logs for this cmd.
+      cmd: The shell cmd to run.
+      log_directory: Where to store the logs for this cmd.
+
+    Raises:
+      update_exception.UpdateException: If the update fails.
     """
     kwds = dict(print_cmd=False, combine_stdout_stderr=True, error_code_ok=True)
     if not self.verbose:
@@ -227,7 +244,8 @@
       unittest: the unittest object running this test.
       output: stdout from a test run.
       percent_required_to_pass: percentage required to pass.  This should be
-        fall between 0-100.
+          fall between 0-100.
+
     Returns:
       percent that passed.
     """
@@ -235,7 +253,7 @@
     self.TestInfo('Percent passed: %d vs. Percent required: %d' % (
         percent_passed, percent_required_to_pass))
     if percent_passed < percent_required_to_pass:
-      print output
+      print(output)
       unittest.fail('%d percent of tests are required to pass' %
                     percent_required_to_pass)
 
@@ -250,7 +268,7 @@
     Each test needs to specify a unique ssh port.
 
     Args:
-      port:  Unique port for ssh access.
+      port: Unique port for ssh access.
     """
     # Initialize port vars.
     self._ssh_port = port
@@ -277,6 +295,7 @@
 
     Args:
       label: The label used to describe this test phase.
+
     Returns:
       Returns a path for the results directory to use for this label.
     """
@@ -295,6 +314,7 @@
 
     Args:
       output: Output string for generate_test_report.py.
+
     Returns:
       The percentage of tests that passed.
     """
diff --git a/au_test_harness/cros_au_test_harness.py b/au_test_harness/cros_au_test_harness.py
index 8f5c388..be6bd07 100755
--- a/au_test_harness/cros_au_test_harness.py
+++ b/au_test_harness/cros_au_test_harness.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python2
 
 # Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
@@ -12,8 +12,10 @@
   being run during the update process.
 """
 
+from __future__ import print_function
+
+import argparse
 import functools
-import optparse
 import os
 import pickle
 import sys
@@ -91,17 +93,17 @@
   return None
 
 
-def _PrepareTestSuite(options):
-  """Returns a prepared test suite given by the options and test class."""
-  au_test.AUTest.ProcessOptions(options)
+def _PrepareTestSuite(opts):
+  """Returns a prepared test suite given by the opts and test class."""
+  au_test.AUTest.ProcessOptions(opts)
   test_loader = unittest.TestLoader()
-  test_loader.testMethodPrefix = options.test_prefix
+  test_loader.testMethodPrefix = opts.test_prefix
   return test_loader.loadTestsFromTestCase(au_test.AUTest)
 
 
-def _RunTestsInParallel(options):
-  """Runs the tests given by the options in parallel."""
-  test_suite = _PrepareTestSuite(options)
+def _RunTestsInParallel(opts):
+  """Runs the tests given by the opts in parallel."""
+  test_suite = _PrepareTestSuite(opts)
   steps = []
   for test in test_suite:
     test_name = test.id()
@@ -110,113 +112,113 @@
 
   logging.info('Running tests in test suite in parallel.')
   try:
-    parallel.RunParallelSteps(steps, max_parallel=options.jobs)
+    parallel.RunParallelSteps(steps, max_parallel=opts.jobs)
   except parallel.BackgroundFailure as ex:
     cros_build_lib.Die(ex)
 
 
-def CheckOptions(parser, options, leftover_args):
-  """Assert given options are valid.
+def CheckOpts(parser, opts):
+  """Assert given opts are valid.
 
   Args:
-    parser: Parser used to parse options.
-    options: Parsed options.
-    leftover_args: Args left after parsing.
+    parser: Parser used to parse opts.
+    opts: Parsed opts.
   """
 
-  if leftover_args: parser.error('Found unsupported flags ' + leftover_args)
-  if not options.type in ['real', 'vm', 'gce']:
+  if not opts.type in ['real', 'vm', 'gce']:
     parser.error('Failed to specify valid test type.')
 
   def _IsValidImage(image):
-    """Asserts that |image_path| is a valid image file for |options.type|."""
+    """Asserts that |image_path| is a valid image file for |opts.type|."""
     return (image is not None) and os.path.isfile(image)
 
-  if not _IsValidImage(options.target_image):
+  if not _IsValidImage(opts.target_image):
     parser.error('Testing requires a valid target image.\n'
                  'Given: type=%s, target_image=%s.' %
-                 (options.type, options.target_image))
+                 (opts.type, opts.target_image))
 
-  if not options.base_image:
+  if not opts.base_image:
     logging.info('No base image supplied.  Using target as base image.')
-    options.base_image = options.target_image
+    opts.base_image = opts.target_image
 
-  if not _IsValidImage(options.base_image):
+  if not _IsValidImage(opts.base_image):
     parser.error('Testing requires a valid base image.\n'
                  'Given: type=%s, base_image=%s.' %
-                 (options.type, options.base_image))
+                 (opts.type, opts.base_image))
 
-  if (options.payload_signing_key and not
-      os.path.isfile(options.payload_signing_key)):
+  if (opts.payload_signing_key and not
+      os.path.isfile(opts.payload_signing_key)):
     parser.error('Testing requires a valid path to the private key.')
 
-  if options.ssh_private_key and not os.path.isfile(options.ssh_private_key):
+  if opts.ssh_private_key and not os.path.isfile(opts.ssh_private_key):
     parser.error('Testing requires a valid path to the ssh private key.')
 
-  if options.test_results_root:
-    if not 'chroot/tmp' in options.test_results_root:
+  if opts.test_results_root:
+    if not 'chroot/tmp' in opts.test_results_root:
       parser.error('Must specify a test results root inside tmp in a chroot.')
 
-    if not os.path.exists(options.test_results_root):
-      os.makedirs(options.test_results_root)
+    if not os.path.exists(opts.test_results_root):
+      os.makedirs(opts.test_results_root)
 
   else:
     chroot_tmp = os.path.join(constants.SOURCE_ROOT, 'chroot', 'tmp')
-    options.test_results_root = tempfile.mkdtemp(
+    opts.test_results_root = tempfile.mkdtemp(
         prefix='au_test_harness', dir=chroot_tmp)
 
 
 def main():
   test_helper.SetupCommonLoggingFormat()
-  parser = optparse.OptionParser()
-  parser.add_option('-b', '--base_image',
-                    help='path to the base image.')
-  parser.add_option('-r', '--board',
-                    help='board for the images.')
-  parser.add_option('--no_delta', action='store_false', default=True,
-                    dest='delta',
-                    help='Disable using delta updates.')
-  parser.add_option('--no_graphics', action='store_true',
-                    help='Disable graphics for the vm test.')
-  parser.add_option('-j', '--jobs', default=test_helper.CalculateDefaultJobs(),
-                    type=int, help='Number of simultaneous jobs')
-  parser.add_option('--payload_signing_key', default=None,
-                    help='Path to the private key used to sign payloads with.')
-  parser.add_option('-q', '--quick_test', default=False, action='store_true',
-                    help='Use a basic test to verify image.')
-  parser.add_option('-m', '--remote',
-                    help='Remote address for real test.')
-  parser.add_option('-t', '--target_image',
-                    help='path to the target image.')
-  parser.add_option('--test_results_root', default=None,
-                    help='Root directory to store test results.  Should '
-                    'be defined relative to chroot root.')
-  parser.add_option('--test_prefix', default='test',
-                    help='Only runs tests with specific prefix i.e. '
-                    'testFullUpdateWipeStateful.')
-  parser.add_option('-p', '--type', default='vm',
-                    help='type of test to run: [vm, real, gce]. Default: vm.')
-  parser.add_option('--verbose', default=True, action='store_true',
-                    help='Print out rather than capture output as much as '
-                    'possible.')
-  parser.add_option('--whitelist_chrome_crashes', default=False,
-                    dest='whitelist_chrome_crashes', action='store_true',
-                    help='Treat Chrome crashes as non-fatal.')
-  parser.add_option('--verify_suite_name', default=None,
-                    help='Specify the verify suite to run.')
-  parser.add_option('--parallel', default=False, dest='parallel',
-                    action='store_true',
-                    help='Run multiple test stages in parallel (applies only '
-                         'to vm tests). Default: False')
-  parser.add_option('--ssh_private_key', default=None,
-                    help='Path to the private key to use to ssh into the image '
-                    'as the root user.')
-  (options, leftover_args) = parser.parse_args()
+  parser = argparse.ArgumentParser()
+  parser.add_argument('-b', '--base_image',
+                      help='path to the base image.')
+  parser.add_argument('-r', '--board',
+                      help='board for the images.')
+  parser.add_argument('--no_delta', action='store_false', default=True,
+                      dest='delta',
+                      help='Disable using delta updates.')
+  parser.add_argument('--no_graphics', action='store_true',
+                      help='Disable graphics for the vm test.')
+  parser.add_argument('-j', '--jobs',
+                      default=test_helper.CalculateDefaultJobs(), type=int,
+                      help='Number of simultaneous jobs')
+  parser.add_argument('--payload_signing_key', default=None,
+                      help='Path to the private key used to sign payloads '
+                      'with.')
+  parser.add_argument('-q', '--quick_test', default=False, action='store_true',
+                      help='Use a basic test to verify image.')
+  parser.add_argument('-m', '--remote',
+                      help='Remote address for real test.')
+  parser.add_argument('-t', '--target_image',
+                      help='path to the target image.')
+  parser.add_argument('--test_results_root', default=None,
+                      help='Root directory to store test results.  Should '
+                      'be defined relative to chroot root.')
+  parser.add_argument('--test_prefix', default='test',
+                      help='Only runs tests with specific prefix i.e. '
+                      'testFullUpdateWipeStateful.')
+  parser.add_argument('-p', '--type', default='vm',
+                      help='type of test to run: [vm, real, gce]. Default: vm.')
+  parser.add_argument('--verbose', default=True, action='store_true',
+                      help='Print out rather than capture output as much as '
+                      'possible.')
+  parser.add_argument('--whitelist_chrome_crashes', default=False,
+                      dest='whitelist_chrome_crashes', action='store_true',
+                      help='Treat Chrome crashes as non-fatal.')
+  parser.add_argument('--verify_suite_name', default=None,
+                      help='Specify the verify suite to run.')
+  parser.add_argument('--parallel', default=False, dest='parallel',
+                      action='store_true',
+                      help='Run multiple test stages in parallel (applies only '
+                      'to vm tests). Default: False')
+  parser.add_argument('--ssh_private_key', default=None,
+                      help='Path to the private key to use to ssh into the '
+                      'image as the root user.')
+  opts = parser.parse_args()
 
-  CheckOptions(parser, options, leftover_args)
+  CheckOpts(parser, opts)
 
   # Generate cache of updates to use during test harness.
-  update_cache = _ReadUpdateCache(options.type, options.target_image)
+  update_cache = _ReadUpdateCache(opts.type, opts.target_image)
   if not update_cache:
     msg = ('No update cache found. Update testing will not work.  Run '
            ' cros_generate_update_payloads if this was not intended.')
@@ -236,15 +238,15 @@
       if update_cache:
         my_server = dev_server_wrapper.DevServerWrapper(
             port=dev_server_wrapper.DEFAULT_PORT,
-            log_dir=options.test_results_root)
+            log_dir=opts.test_results_root)
         my_server.Start()
 
-      if options.type == 'vm' or options.type == 'gce' and options.parallel:
-        _RunTestsInParallel(options)
+      if opts.type == 'vm' or opts.type == 'gce' and opts.parallel:
+        _RunTestsInParallel(opts)
       else:
         # TODO(sosa) - Take in a machine pool for a real test.
         # Can't run in parallel with only one remote device.
-        test_suite = _PrepareTestSuite(options)
+        test_suite = _PrepareTestSuite(opts)
         test_result = unittest.TextTestRunner().run(test_suite)
         if not test_result.wasSuccessful():
           cros_build_lib.Die('Test harness failed.')
diff --git a/au_test_harness/cros_test_proxy.py b/au_test_harness/cros_test_proxy.py
index 22c9dd9..9a105f6 100644
--- a/au_test_harness/cros_test_proxy.py
+++ b/au_test_harness/cros_test_proxy.py
@@ -4,6 +4,8 @@
 
 """Module containing classes pertaining to inserting a proxy in a test."""
 
+from __future__ import print_function
+
 import os
 import select
 import socket
@@ -46,14 +48,14 @@
 
     def setup(self):
       """Setup is called once for each connection proxied."""
-      self.server.filter.setup()
+      self.server.data_filter.setup()
 
     def handle(self):
       """Handles each incoming connection.
 
          Opens a new connection to the port we are proxing to, then
          passes each packet along in both directions after passing
-         them through the filter object passed in.
+         them through the Filter object passed in.
       """
       # Open outgoing socket
       s_in = self.request
@@ -61,12 +63,13 @@
       s_out.connect((self.server.address_out, self.server.port_out))
 
       while True:
-        rlist, wlist, xlist = select.select([s_in, s_out], [], [])
+        rlist, _, _ = select.select([s_in, s_out], [], [])
 
         if s_in in rlist:
           data = s_in.recv(1024)
-          data = self.server.filter.InBound(data)
-          if not data: break
+          data = self.server.data_filter.InBound(data)
+          if not data:
+            break
           try:
             # If there is any error sending data, close both connections.
             s_out.sendall(data)
@@ -75,8 +78,9 @@
 
         if s_out in rlist:
           data = s_out.recv(1024)
-          data = self.server.filter.OutBound(data)
-          if not data: break
+          data = self.server.data_filter.OutBound(data)
+          if not data:
+            break
           try:
             # If there is any error sending data, close both connections.
             s_in.sendall(data)
@@ -87,21 +91,21 @@
       s_out.close()
 
   def __init__(self,
-               filter,
+               data_filter,
                port_in=8081,
                address_out='127.0.0.1', port_out=8080):
     """Configures the proxy object.
 
     Args:
-      filter: An instance of a subclass of Filter.
+      data_filter: An instance of a subclass of Filter.
       port_in: Port on which to listen for incoming connections.
       address_out: Address to which outgoing connections will go.
-      address_port: Port to which outgoing connections will go.
+      port_out: Port to which outgoing connections will go.
     """
     self.port_in = port_in
     self.address_out = address_out
     self.port_out = port_out
-    self.filter = filter
+    self.data_filter = data_filter
 
     # Used to coordinate startup/shutdown in a new thread.
     self.__is_started = threading.Event()
@@ -148,7 +152,7 @@
       # connecting to the socket to wake this up instead of
       # polling. Polling reduces our responsiveness to a
       # shutdown request and wastes cpu at all other times.
-      r, w, e = select.select([self], [], [], poll_interval)
+      r, _, _ = select.select([self], [], [], poll_interval)
       if r:
         self._handle_request_noblock()
 
@@ -167,4 +171,3 @@
     """
     self.__serving = False
     self.__is_shut_down.wait()
-
diff --git a/au_test_harness/gce_au_worker_unittest.py b/au_test_harness/gce_au_worker_unittest.py
index e88de00..20ba25b 100755
--- a/au_test_harness/gce_au_worker_unittest.py
+++ b/au_test_harness/gce_au_worker_unittest.py
@@ -306,15 +306,16 @@
                      return_value=(0, None, None))
 
     # Fake resource existance.
-    remote_instance = 'fake-remote-instance'
-    self.PatchObject(worker.gce_context, 'InstanceExists', autospec=True,
-                     side_effect=lambda instance: remote_instance is not None)
+    remote_instances = ('fake-remote-instance',)
+    self.PatchObject(
+        worker.gce_context, 'InstanceExists', autospec=True,
+        side_effect=lambda instance: instance in remote_instances)
 
     # Fake resource deletors.
     self.PatchObject(worker.gce_context, 'DeleteImage', autospec=True)
     # Make DeleteInstance delete the remote resource.
-    def _OverrideDeleteInstance(_):
-      remote_instance = None
+    def _OverrideDeleteInstance(instance):
+      remote_instances.remove(instance)
     self.PatchObject(worker.gce_context, 'DeleteInstance', autospec=True,
                      side_effect=_OverrideDeleteInstance)
 
diff --git a/au_test_harness/real_au_worker.py b/au_test_harness/real_au_worker.py
index 6da9ab9..b6fa0a2 100644
--- a/au_test_harness/real_au_worker.py
+++ b/au_test_harness/real_au_worker.py
@@ -4,6 +4,8 @@
 
 """Module containing class that implements an au_worker for a test device."""
 
+from __future__ import print_function
+
 import constants
 from chromite.lib import cros_build_lib
 from chromite.lib import path_util
@@ -47,13 +49,15 @@
            stateful_change_flag,
            '--verify',
           ]
-    if proxy_port: cmd.append('--proxy_port=%s' % proxy_port)
+    if proxy_port:
+      cmd.append('--proxy_port=%s' % proxy_port)
     self.RunUpdateCmd(cmd)
 
   def VerifyImage(self, unittest, percent_required_to_pass=100, test=''):
     """Verifies an image using test_that with verification suite."""
     test_directory, _ = self.GetNextResultsPath('autotest_tests')
-    if not test: test = self.verify_suite
+    if not test:
+      test = self.verify_suite
 
     cmd = ['test_that', '--no-quickmerge', '--results_dir=%s' % test_directory,
            self.remote, test]
@@ -67,4 +71,3 @@
 
     return self.AssertEnoughTestsPassed(unittest, result.output,
                                         percent_required_to_pass)
-
diff --git a/au_test_harness/vm_au_worker.py b/au_test_harness/vm_au_worker.py
index 4bfa724..7471978 100644
--- a/au_test_harness/vm_au_worker.py
+++ b/au_test_harness/vm_au_worker.py
@@ -4,6 +4,8 @@
 
 """Module containing implementation of an au_worker for virtual machines."""
 
+from __future__ import print_function
+
 import os
 import shutil
 import tempfile
@@ -23,7 +25,8 @@
     """Processes vm-specific options."""
     super(VMAUWorker, self).__init__(options, test_results_root)
     self.graphics_flag = ''
-    if options.no_graphics: self.graphics_flag = '--no_graphics'
+    if options.no_graphics:
+      self.graphics_flag = '--no_graphics'
     if not self.board:
       cros_build_lib.Die('Need board to convert base image to vm.')
     self.whitelist_chrome_crashes = options.whitelist_chrome_crashes
@@ -125,7 +128,8 @@
            '--ssh_port=%s' % self._ssh_port,
            stateful_change_flag,
           ]
-    if proxy_port: cmd.append('--proxy_port=%s' % proxy_port)
+    if proxy_port:
+      cmd.append('--proxy_port=%s' % proxy_port)
     self.TestInfo(self.GetUpdateMessage(update_path, None, True, proxy_port))
     try:
       self.RunUpdateCmd(cmd, log_directory)
@@ -137,10 +141,8 @@
                         payload_signing_key, for_vm=False):
     """Appends common args to an update cmd defined by an array.
 
-    Calls super function with for_vm set to True.
-
-    Args:
-      See AppendUpdateFlags for description of args.
+    Calls super function with for_vm set to True. See base class for
+    descriptions for arguments.
     """
     super(VMAUWorker, self).AppendUpdateFlags(
         cmd, image_path, src_image_path, proxy_port, payload_signing_key,
@@ -150,7 +152,7 @@
     # VMAUWorker disregards |unittest| and |percent_required_to_pass|.
     return self._VerifyImage(test)
 
-  # pylint: disable-msg=W0221
+  # pylint: disable=W0221
   def _VerifyImage(self, test=''):
     """Runs vm smoke suite or any single test to verify image.
 
@@ -160,7 +162,8 @@
     (_, _, log_directory_in_chroot) = log_directory.rpartition('chroot')
     # image_to_live already verifies lsb-release matching.  This is just
     # for additional steps.
-    if not test: test = self.verify_suite
+    if not test:
+      test = self.verify_suite
 
     command = ['./bin/cros_run_vm_test',
                '--board=%s' % self.board,
@@ -172,7 +175,8 @@
                '--verbose=0',
                test,
               ]
-    if self.graphics_flag: command.append(self.graphics_flag)
+    if self.graphics_flag:
+      command.append(self.graphics_flag)
     if self.whitelist_chrome_crashes:
       command.append('--whitelist_chrome_crashes')
     if self.ssh_private_key is not None:
@@ -186,7 +190,7 @@
 
     # If the command failed or printed warnings, print the output.
     if result.returncode != 0 or '@@@STEP_WARNINGS@@@' in result.output:
-      print result.output
+      print(result.output)
       self._HandleFail(log_directory, fail_directory)
 
     return result.returncode == 0
diff --git a/ctest/ctest.py b/ctest/ctest.py
index 940077f..7cc0675 100755
--- a/ctest/ctest.py
+++ b/ctest/ctest.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python2
 #
 # Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
@@ -6,8 +6,9 @@
 
 """Wrapper for tests that are run on builders."""
 
-import logging
-import optparse
+from __future__ import print_function
+
+import argparse
 import os
 import sys
 
@@ -17,6 +18,7 @@
 sys.path.append(constants.CROS_PLATFORM_ROOT)
 
 from chromite.lib import cros_build_lib
+from chromite.lib import cros_logging as logging
 from crostestutils.lib import image_extractor
 from crostestutils.lib import test_helper
 
@@ -46,25 +48,25 @@
     whitelist_chrome_crashes: Whether to treat Chrome crashes as non-fatal.
   """
 
-  def __init__(self, options):
+  def __init__(self, opts):
     """Initializes the test object.
 
     Args:
-      options:  Parsed options for module.
+      opts: Parsed args for module.
     """
     self.base = None
-    self.board = options.board
-    self.archive_dir = options.archive_dir
+    self.board = opts.board
+    self.archive_dir = opts.archive_dir
     self.crosutils_root = os.path.join(constants.SOURCE_ROOT, 'src', 'scripts')
-    self.no_graphics = options.no_graphics
-    self.remote = options.remote
+    self.no_graphics = opts.no_graphics
+    self.remote = opts.remote
     # TODO(sosa):  Remove once signed payload bug is resolved.
-    #self.sign_payloads = not options.cache
+    #self.sign_payloads = not opts.cache
     self.sign_payloads = False
-    self.target = options.target_image
-    self.test_results_root = options.test_results_root
-    self.type = options.type
-    self.whitelist_chrome_crashes = options.whitelist_chrome_crashes
+    self.target = opts.target_image
+    self.test_results_root = opts.test_results_root
+    self.type = opts.type
+    self.whitelist_chrome_crashes = opts.whitelist_chrome_crashes
 
     self.public_key = None
     if self.sign_payloads:
@@ -74,11 +76,11 @@
     else:
       self.payload_signing_key = None
 
-    self.jobs = options.jobs
-    self.nplus1_archive_dir = options.nplus1_archive_dir
+    self.jobs = opts.jobs
+    self.nplus1_archive_dir = opts.nplus1_archive_dir
 
     # An optional ssh private key used for testing.
-    self.ssh_private_key = options.ssh_private_key
+    self.ssh_private_key = opts.ssh_private_key
 
   def GeneratePublicKey(self):
     """Returns the path to a generated public key from the UE private key."""
@@ -143,7 +145,8 @@
     else:
       cmd.append('--basic_suite')
 
-    if self.type != 'vm': cmd.append('--novm')
+    if self.type != 'vm':
+      cmd.append('--novm')
     try:
       cros_build_lib.RunCommand(cmd, cwd=self.crosutils_root)
     except cros_build_lib.RunCommandError:
@@ -164,6 +167,8 @@
     Args:
       only_verify: Only verify the target image.
       quick_update: Do a quick update test.
+      suite: The suite of tests to run.
+
     Raises:
       TestException: If the cros_au_test_harness command returns an error code.
     """
@@ -189,10 +194,12 @@
     elif quick_update:
       cmd.append('--test_prefix=SimpleTestUpdateAndVerify')
 
-    if self.test_results_root: cmd.append('--test_results_root=%s' %
-                                          self.test_results_root)
-    if self.no_graphics: cmd.append('--no_graphics')
-    if self.whitelist_chrome_crashes: cmd.append('--whitelist_chrome_crashes')
+    if self.test_results_root:
+      cmd.append('--test_results_root=%s' % self.test_results_root)
+    if self.no_graphics:
+      cmd.append('--no_graphics')
+    if self.whitelist_chrome_crashes:
+      cmd.append('--whitelist_chrome_crashes')
 
     # We did not generate signed payloads if this is a |quick_update| test.
     if not quick_update and self.sign_payloads:
@@ -208,78 +215,74 @@
 
 def main():
   test_helper.SetupCommonLoggingFormat()
-  parser = optparse.OptionParser()
-  parser.add_option('-b', '--board',
-                    help='board for the image to compare against.')
-  parser.add_option('--archive_dir',
-                    help='Directory containing previously archived images.')
-  parser.add_option('--cache', default=False, action='store_true',
-                    help='Cache payloads')
-  parser.add_option('--jobs', default=test_helper.CalculateDefaultJobs(),
-                    type=int,
-                    help='Number of threads to run in parallel.')
-  parser.add_option('--no_graphics', action='store_true', default=False,
-                    help='Disable graphics for the vm test.')
-  parser.add_option('--only_verify', action='store_true', default=False,
-                    help='Only run basic verification suite.')
-  parser.add_option('--quick_update', action='store_true',
-                    help='Run a quick update test. This will run a subset of '
-                         'test suite after running autoupdate from target '
-                         'image to itself.')
-  parser.add_option('--nplus1_archive_dir', default=None,
-                    help='If set, directory to archive nplus1 payloads.')
-  parser.add_option('--remote', default='0.0.0.0',
-                    help='For real tests, ip address of the target machine.')
-  parser.add_option('--target_image', default=None,
-                    help='Target image to test.')
-  parser.add_option('--suite', default=None, help='Test suite to run.')
-  parser.add_option('--test_results_root', default=None,
-                    help='Root directory to store test results.  Should '
-                    'be defined relative to chroot root.')
-  parser.add_option('--type', default='vm',
-                    help='type of test to run: [vm, real, gce]. Default: vm.')
-  parser.add_option('--verbose', default=False, action='store_true',
-                    help='Print out added debugging information')
-  parser.add_option('--whitelist_chrome_crashes', default=False,
-                    dest='whitelist_chrome_crashes', action='store_true',
-                    help='Treat Chrome crashes as non-fatal.')
-  parser.add_option('--ssh_private_key', default=None,
-                    help='Path to the private key to use to ssh into the image '
-                    'as the root user')
+  parser = argparse.ArgumentParser()
+  parser.add_argument('-b', '--board',
+                      help='board for the image to compare against.')
+  parser.add_argument('--archive_dir',
+                      help='Directory containing previously archived images.')
+  parser.add_argument('--cache', default=False, action='store_true',
+                      help='Cache payloads')
+  parser.add_argument('--jobs', default=test_helper.CalculateDefaultJobs(),
+                      type=int,
+                      help='Number of threads to run in parallel.')
+  parser.add_argument('--no_graphics', action='store_true', default=False,
+                      help='Disable graphics for the vm test.')
+  parser.add_argument('--only_verify', action='store_true', default=False,
+                      help='Only run basic verification suite.')
+  parser.add_argument('--quick_update', action='store_true',
+                      help='Run a quick update test. This will run a subset of '
+                      'test suite after running autoupdate from target '
+                      'image to itself.')
+  parser.add_argument('--nplus1_archive_dir', default=None,
+                      help='If set, directory to archive nplus1 payloads.')
+  parser.add_argument('--remote', default='0.0.0.0',
+                      help='For real tests, ip address of the target machine.')
+  parser.add_argument('--target_image', default=None,
+                      help='Target image to test.')
+  parser.add_argument('--suite', default=None, help='Test suite to run.')
+  parser.add_argument('--test_results_root', default=None,
+                      help='Root directory to store test results.  Should '
+                      'be defined relative to chroot root.')
+  parser.add_argument('--type', default='vm',
+                      help='type of test to run: [vm, real, gce]. Default: vm.')
+  parser.add_argument('--verbose', default=False, action='store_true',
+                      help='Print out added debugging information')
+  parser.add_argument('--whitelist_chrome_crashes', default=False,
+                      dest='whitelist_chrome_crashes', action='store_true',
+                      help='Treat Chrome crashes as non-fatal.')
+  parser.add_argument('--ssh_private_key', default=None,
+                      help='Path to the private key to use to ssh into the '
+                      'image as the root user')
 
-  # Set the usage to include flags.
-  def _ParserError(msg):
-    print >> sys.stderr, parser.format_help()
-    print >> sys.stderr, 'Error: %s' % msg
-    sys.exit(2)
-  parser.error = _ParserError
-  (options, args) = parser.parse_args()
+  opts = parser.parse_args()
 
-  if args: parser.error('Extra args found %s.' % args)
-  if not options.board: parser.error('Need board for image to compare against.')
-  if options.only_verify and options.quick_update: parser.error(
-      'Only one of --only_verify or --quick_update should be specified.')
+  if not opts.board:
+    parser.error('Need board for image to compare against.')
+  if opts.only_verify and opts.quick_update:
+    parser.error(
+        'Only one of --only_verify or --quick_update should be specified.')
 
-  # force absolute path for these options, since a chdir occurs deeper in the
+  # force absolute path for these opts, since a chdir occurs deeper in the
   # codebase.
   for x in ('nplus1_archive_dir', 'target_image', 'test_results_root'):
-    if x == 'target_image' and options.type == 'gce':
+    if x == 'target_image' and opts.type == 'gce':
       # In this case |target_image| is a Google Storage path.
       continue
-    val = getattr(options, x)
+    val = getattr(opts, x)
     if val is not None:
-      setattr(options, x, os.path.abspath(val))
+      setattr(opts, x, os.path.abspath(val))
 
-  ctest = CTest(options)
-  if ctest.sign_payloads: ctest.GeneratePublicKey()
+  ctest = CTest(opts)
+  if ctest.sign_payloads:
+    ctest.GeneratePublicKey()
   ctest.FindTargetAndBaseImages()
-  if not options.only_verify:
-    ctest.GenerateUpdatePayloads(not options.quick_update)
+  if not opts.only_verify:
+    ctest.GenerateUpdatePayloads(not opts.quick_update)
   try:
-    ctest.RunAUTestHarness(options.only_verify, options.quick_update,
-                           options.suite)
+    ctest.RunAUTestHarness(opts.only_verify, opts.quick_update,
+                           opts.suite)
   except TestException as e:
-    if options.verbose:
+    if opts.verbose:
       cros_build_lib.Die(str(e))
 
     sys.exit(1)
diff --git a/ctest/ctest_unittest.py b/ctest/ctest_unittest.py
index 3732f57..d2a5656 100755
--- a/ctest/ctest_unittest.py
+++ b/ctest/ctest_unittest.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python2
 #
 # Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
@@ -6,6 +6,8 @@
 
 """Test module containing unittests for CTest."""
 
+from __future__ import print_function
+
 import mox
 import os
 import sys
@@ -37,12 +39,15 @@
 
     # TODO(sosa): Can we create mock objects but call a real method in an easier
     # way?
-    ctest.CTest.__init__()
+    ctest.CTest.__init__(None)
+    # pylint: disable=no-value-for-parameter
+    # For some reason pylint is not happy with the way mox mocks out functions.
     image_extractor.ImageExtractor.GetLatestImage(
         'target_version').AndReturn(None)
+    # pylint: enable=no-value-for-parameter
 
     self.mox.ReplayAll()
-    ctester = ctest.CTest() # Calls mocked out __init__.
+    ctester = ctest.CTest(None) # Calls mocked out __init__.
     ctester.target = 'some_image/target_version/file.bin'
     ctester.base = None
     ctester.archive_dir = self.ARCHIVE_DIR
@@ -64,14 +69,16 @@
     latest_base_path = os.path.join(
         '/some/fake/path', image_extractor.ImageExtractor.IMAGE_TO_EXTRACT)
 
-    ctest.CTest.__init__()
+    ctest.CTest.__init__(None)
+    # pylint: disable=no-value-for-parameter
     image_extractor.ImageExtractor.GetLatestImage('target_version').AndReturn(
         latest_base_dir)
     image_extractor.ImageExtractor.UnzipImage(latest_base_dir).AndReturn(
         latest_base_path)
+    # pylint: enable=no-value-for-parameter
 
     self.mox.ReplayAll()
-    ctester = ctest.CTest() # Calls mocked out __init__.
+    ctester = ctest.CTest(None) # Calls mocked out __init__.
     ctester.target = 'some_image/target_version/file.bin'
     ctester.base = None
     ctester.archive_dir = self.ARCHIVE_DIR
@@ -94,15 +101,17 @@
 
     fake_crosutils = os.path.join(self.FAKE_ROOT, 'src', 'scripts')
 
-    ctest.CTest.__init__()
+    ctest.CTest.__init__(None)
     cros_build_lib.RunCommand(
         mox.In('./get_latest_image.sh'), cwd=fake_crosutils, print_cmd=False,
         redirect_stdout=True).AndReturn(fake_result)
+    # pylint: disable=no-value-for-parameter
     image_extractor.ImageExtractor.GetLatestImage('latest_version').AndReturn(
         None)
+    # pylint: enable=no-value-for-parameter
 
     self.mox.ReplayAll()
-    ctester = ctest.CTest() # Calls mocked out __init__.
+    ctester = ctest.CTest(None) # Calls mocked out __init__.
     ctester.target = None
     ctester.base = None
     ctester.archive_dir = self.ARCHIVE_DIR
diff --git a/lib/constants.py b/lib/constants.py
index 9c01596..f8f7055 100644
--- a/lib/constants.py
+++ b/lib/constants.py
@@ -2,6 +2,10 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+"""Module containing contants to be used across crostestutils."""
+
+from __future__ import print_function
+
 import os
 
 _TEST_LIB_PATH = os.path.realpath(__file__)