Adding a CORS bypass integration test

tools/chrome_proxy/webdriver/bypass.py

 # Copyright 2017 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 common
 from common import TestDriver
 from common import IntegrationTest
 
 
 class Bypass(IntegrationTest):
 
   # Ensure Chrome does not use Data Saver for block=0, which uses the default
   # proxy retry delay.
   def testBypass(self):
     with TestDriver() as t:
       t.AddChromeArg('--enable-spdy-proxy-auth')
       t.LoadURL('http://check.googlezip.net/block/')
       for response in t.GetHTTPResponses():
         self.assertNotHasChromeProxyViaHeader(response)
 
       # Load another page and check that Data Saver is not used.
       t.LoadURL('http://check.googlezip.net/test.html')
       for response in t.GetHTTPResponses():
         self.assertNotHasChromeProxyViaHeader(response)
 
+  # Verify that CORS requests receive a block-once from the data reduction
+  # proxy by checking that those requests are retried without data reduction
+  # proxy.
+  def testCorsBypass(self):
+    with TestDriver() as test_driver:
+      test_driver.AddChromeArg('--enable-spdy-proxy-auth')
+      test_driver.LoadURL('http://www.gstatic.com/chrome/googlezip/cors/')
+
+      # Navigate to a different page to verify that later requests are not
+      # blocked.
+      test_driver.LoadURL('http://check.googlezip.net/test.html')
+
+      cors_requests = 0
+      same_origin_requests = 0
+      for response in test_driver.GetHTTPResponses():
+        # The origin header implies that |response| is a CORS request.
+        if ('origin' not in response.request_headers):
+          self.assertHasChromeProxyViaHeader(response)
+          same_origin_requests = same_origin_requests + 1
+        else:
+          self.assertNotHasChromeProxyViaHeader(response)
+          cors_requests = cors_requests + 1
+      # Verify that both CORS and same origin requests were seen.
+      self.assertNotEqual(0, same_origin_requests)
+      self.assertNotEqual(0, cors_requests)
+
 if __name__ == '__main__':
   IntegrationTest.RunAllTests()