Clean the machine before running commands in the mini_installer test framework.

chrome/test/mini_installer/uninstall_chrome.py

 # Copyright 2013 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.
 
 """Uninstalls Chrome.
 
 This script reads the uninstall command from registry, calls it, and verifies
 the output status code.
 """
 
 import _winreg
 import optparse
 import subprocess
 import sys
 
 
 def main():
   parser = optparse.OptionParser(description='Uninstall Chrome.')
   parser.add_option('--system-level', action='store_true', dest='system_level',
                     default=False, help='Uninstall Chrome at system level.')
   parser.add_option('--chrome-long-name', default='Google Chrome',
                     help='Google Chrome or Chromium)')
+  parser.add_option('--interactive', action='store_true', dest='interactive',
+                    default=False, help='Ask before uninstalling Chrome.')
+  parser.add_option('--no-error-if-absent', action='store_true',
+                    dest='no_error_if_absent', default=False,
+                    help='No error if the registry key for uninstalling Chrome '
+                         'is absent.')
   options, _ = parser.parse_args()
 
   # TODO(sukolsak): Add support for uninstalling MSI-based Chrome installs when
   # we support testing MSIs.
   if options.system_level:
     root_key = _winreg.HKEY_LOCAL_MACHINE
   else:
     root_key = _winreg.HKEY_CURRENT_USER
   sub_key = ('SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\%s' %
              options.chrome_long_name)
   # Query the key. It will throw a WindowsError if the key doesn't exist.
   try:
     key = _winreg.OpenKey(root_key, sub_key, 0, _winreg.KEY_QUERY_VALUE)
   except WindowsError:
+    if options.no_error_if_absent:
+      return 0
     raise KeyError('Registry key %s\\%s is missing' % (
         'HKEY_LOCAL_MACHINE' if options.system_level else 'HKEY_CURRENT_USER',
         sub_key))
+  if options.interactive:
+    prompt = ('Warning: This will uninstall %s at %s. Do you want to continue? '
+              '(y/N) ' % (options.chrome_long_name,
+                          'system-level' if
+                              options.system_level else 'user-level'))
+    if raw_input(prompt).strip() != 'y':
+      print >> sys.stderr, 'User aborted'
+      return 1
   uninstall_string, _ = _winreg.QueryValueEx(key, 'UninstallString')
   exit_status = subprocess.call(uninstall_string + ' --force-uninstall',
                                 shell=True)
   # The exit status for successful uninstallation of Chrome is 19 (see
   # chrome/installer/util/util_constants.h).
   if exit_status != 19:
     raise Exception('Could not uninstall Chrome. The installer exited with '
                     'status %d.' % exit_status)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())