[chrome_remote_control] Use monkey patching for stubs.

tools/chrome_remote_control/chrome_remote_control/desktop_browser_finder_unittest.py

 # Copyright (c) 2012 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.
 import unittest
 
 from chrome_remote_control import browser_options
 from chrome_remote_control import desktop_browser_finder
-from chrome_remote_control.system_stub import (
-  OSModuleStub,
-  SysModuleStub
-  )
+from chrome_remote_control import system_stub
 
 # This file verifies the logic for finding a browser instance on all platforms
 # at once. It does so by providing stubs for the OS/sys/subprocess primitives
 # that the underlying finding logic usually uses to locate a suitable browser.
 # We prefer this approach to having to run the same test on every platform on
 # which we want this code to work.
 
-class StubSubprocess(object):
-  def __init__(self):
-    self.call_hook = None
-
-  def call(self, *args, **kwargs):
-    assert self.call_hook
-    return self.call_hook(*args, **kwargs)
-
 class FindTestBase(unittest.TestCase):
   def setUp(self):
     self._options = browser_options.BrowserOptions()
     self._options.chrome_root = '../../../'
-    self._sys_stub = SysModuleStub()
-    self._os_stub = OSModuleStub(self._sys_stub)
-    self._subprocess_stub = StubSubprocess()
+    self._stubs = system_stub.Override(desktop_browser_finder,
+                                       ['os', 'subprocess', 'sys'])
+
+  def tearDown(self):
+    self._stubs.Restore()
 
   @property
   def _files(self):
-    return self._os_stub.files
+    return self._stubs.os.path.files
 
   def DoFindAll(self):
-    return desktop_browser_finder.FindAllAvailableBrowsers(self._options,
-        self._os_stub, self._sys_stub, self._subprocess_stub)
+    return desktop_browser_finder.FindAllAvailableBrowsers(self._options)
 
   def DoFindAllTypes(self):
     browsers = self.DoFindAll()
     return [b.browser_type for b in browsers]
 
 def has_type(array, browser_type):
   return len([x for x in array if x.browser_type == browser_type]) != 0
 
 class OSXFindTest(FindTestBase):
   def setUp(self):
     super(OSXFindTest, self).setUp()
-    self._sys_stub.platform = 'darwin'
+    self._stubs.sys.platform = 'darwin'
     self._files.append('/Applications/Google Chrome Canary.app/'
                        'Contents/MacOS/Google Chrome Canary')
     self._files.append('/Applications/Google Chrome.app/' +
                        'Contents/MacOS/Google Chrome')
     self._files.append(
       '../../../out/Release/Chromium.app/Contents/MacOS/Chromium')
     self._files.append(
       '../../../out/Debug/Chromium.app/Contents/MacOS/Chromium')
     self._files.append(
       '../../../out/Release/Content Shell.app/Contents/MacOS/Content Shell')
     self._files.append(
       '../../../out/Debug/Content Shell.app/Contents/MacOS/Content Shell')
 
   def testFindAll(self):
     types = self.DoFindAllTypes()
     self.assertEquals(
       set(types),
       set(['debug', 'release',
            'content-shell-debug', 'content-shell-release',
            'canary', 'system']))
 
 
 class LinuxFindTest(FindTestBase):
   def setUp(self):
     super(LinuxFindTest, self).setUp()
 
-    self._sys_stub.platform = 'linux2'
+    self._stubs.sys.platform = 'linux2'
     self._files.append('/foo/chrome')
     self._files.append('../../../out/Release/chrome')
     self._files.append('../../../out/Debug/chrome')
     self._files.append('../../../out/Release/content_shell')
     self._files.append('../../../out/Debug/content_shell')
 
     self.has_google_chrome_on_path = False
     this = self
     def call_hook(*args, **kwargs): # pylint: disable=W0613
       if this.has_google_chrome_on_path:
         return 0
       raise OSError('Not found')
-    self._subprocess_stub.call_hook = call_hook
+    self._stubs.subprocess.call = call_hook
 
   def testFindAllWithExact(self):
     types = self.DoFindAllTypes()
     self.assertEquals(
         set(types),
         set(['debug', 'release',
              'content-shell-debug', 'content-shell-release']))
 
   def testFindWithProvidedExecutable(self):
     self._options.browser_executable = '/foo/chrome'
@@ skipping 13 matching lines @@
                       self.DoFindAllTypes())
 
   def testFindUsingRelease(self):
     self.assertTrue('release' in self.DoFindAllTypes())
 
 
 class WinFindTest(FindTestBase):
   def setUp(self):
     super(WinFindTest, self).setUp()
 
-    self._sys_stub.platform = 'win32'
-    self._os_stub.local_app_data = 'c:\\Users\\Someone\\AppData\\Local'
+    self._stubs.sys.platform = 'win32'
+    self._stubs.os.local_app_data = 'c:\\Users\\Someone\\AppData\\Local'
     self._files.append('c:\\tmp\\chrome.exe')
     self._files.append('..\\..\\..\\build\\Release\\chrome.exe')
     self._files.append('..\\..\\..\\build\\Debug\\chrome.exe')
     self._files.append('..\\..\\..\\build\\Release\\content_shell.exe')
     self._files.append('..\\..\\..\\build\\Debug\\content_shell.exe')
-    self._files.append(self._os_stub.local_app_data + '\\' +
+    self._files.append(self._stubs.os.local_app_data + '\\' +
                        'Google\\Chrome\\Application\\chrome.exe')
-    self._files.append(self._os_stub.local_app_data + '\\' +
+    self._files.append(self._stubs.os.local_app_data + '\\' +
                        'Google\\Chrome SxS\\Application\\chrome.exe')
 
   def testFindAllGivenDefaults(self):
     types = self.DoFindAllTypes()
     self.assertEquals(set(types),
                       set(['debug', 'release',
                            'content-shell-debug', 'content-shell-release',
                            'system', 'canary']))
 
   def testFindAllWithExact(self):
     self._options.browser_executable = 'c:\\tmp\\chrome.exe'
     types = self.DoFindAllTypes()
     self.assertEquals(
         set(types),
         set(['exact',
              'debug', 'release',
              'content-shell-debug', 'content-shell-release',
              'system', 'canary']))