Use devtools to set user agent in chromedriver

chrome/test/chromedriver/test/run_py_tests.py

 #!/usr/bin/env python
 # 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.
 
 """End to end tests for ChromeDriver."""
 
 import base64
 import json
 import math
@@ skipping 1818 matching lines @@
 
     Verifies that a log message is written into the specified log file.
     """
     tmp_log_path = tempfile.NamedTemporaryFile()
     driver = self.CreateDriver(chrome_log_path=tmp_log_path.name)
     driver.ExecuteScript('console.info("%s")' % self.LOG_MESSAGE)
     driver.Quit()
     self.assertTrue(self.LOG_MESSAGE in open(tmp_log_path.name).read())
 
 
-class MobileEmulationCapabilityTest(ChromeDriverBaseTest):
+class MobileEmulationCapabilityTest(ChromeDriverBaseTestWithWebServer):
   """Tests that ChromeDriver processes chromeOptions.mobileEmulation.
 
   Makes sure the device metrics are overridden in DevTools and user agent is
   overridden in Chrome.
   """
 
   @staticmethod
   def GlobalSetUp():
     def respondWithUserAgentString(request):
       return {}, """
@@ skipping 48 matching lines @@
     self.assertEqual(360, driver.ExecuteScript('return window.screen.width'))
     self.assertEqual(640, driver.ExecuteScript('return window.screen.height'))
 
   def testUserAgent(self):
     driver = self.CreateDriver(
         mobile_emulation = {'userAgent': 'Agent Smith'})
     driver.Load(self._http_server.GetUrl() + '/userAgent')
     body_tag = driver.FindElement('tag name', 'body')
     self.assertEqual("Agent Smith", body_tag.GetText())
 
+  def testUserAgentNewTab(self):
+    driver = self.CreateDriver(
+        mobile_emulation = {'userAgent': 'Agent Smith'})
+    driver.Load(self.GetHttpUrlForFile('/chromedriver/newtab.html'))
+    old_windows = driver.GetWindowHandles()
+    link = driver.FindElements('tag name', 'a')[0]
+    driver.MouseMoveTo(link)
+    driver.MouseClick()

[stgao, 2017/04/05 04:17:08]

What's the user-agent if the new tab itself directly loads the "/userAgent"
below before Devtools connects to the new tab and instructs it to simulate the
user-agent?

[irisu, 2017/04/05 06:44:33]

Sorry for that misunderstanding. Modified the test and you are correct - this
test now fails.

I will try looking at the docs for a fix, otherwise it may be best to add the
user-agent flag to headless after all to avoid this.

[Sami, 2017/04/05 13:52:04]

Right, looks like we need to support a default user agent after all for this
reason.

+    new_window = self.WaitForNewWindow(driver, old_windows)
+    driver.SwitchToWindow(new_window)
+    driver.Load(self._http_server.GetUrl() + '/userAgent')

[stgao, 2017/04/05 04:17:08]

Before this load, we already instruct the new tab to simulate the user-agent
above, so this load will return the simulated one for sure.

I'm curious about the user-agent of the page that the new tab loads by itself
when opened.

+    body_tag = driver.FindElement('tag name', 'body')
+    self.assertEqual("Agent Smith", body_tag.GetText())
+
   def testDeviceName(self):
     driver = self.CreateDriver(
         mobile_emulation = {'deviceName': 'Google Nexus 5'})
     driver.Load(self._http_server.GetUrl() + '/userAgentUseDeviceWidth')
     self.assertEqual(360, driver.ExecuteScript('return window.screen.width'))
     self.assertEqual(640, driver.ExecuteScript('return window.screen.height'))
     body_tag = driver.FindElement('tag name', 'body')
     self.assertEqual(
         'Mozilla/5.0 (Linux; Android 4.4.4; Nexus 5 Build/KTU84P) '
         'AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.114 Mobile '
@@ skipping 500 matching lines @@
 
   all_tests_suite = unittest.defaultTestLoader.loadTestsFromModule(
       sys.modules[__name__])
   tests = unittest_util.FilterTestSuite(all_tests_suite, options.filter)
   ChromeDriverTest.GlobalSetUp()
   MobileEmulationCapabilityTest.GlobalSetUp()
   result = unittest.TextTestRunner(stream=sys.stdout, verbosity=2).run(tests)
   ChromeDriverTest.GlobalTearDown()
   MobileEmulationCapabilityTest.GlobalTearDown()
   sys.exit(len(result.failures) + len(result.errors))