Added integration test to Chrome Proxy to verify direct connection on remote site timeout

tools/chrome_proxy/integration_tests/chrome_proxy_metrics.py

 # Copyright 2014 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 logging
 import os
 import time
 
 from common import chrome_proxy_metrics
 from common import network_metrics
@@ skipping 854 matching lines @@
           'Expected 1 pingback success and no failures, but '
           'there were %d succesful pingbacks and %d failed pingback attempts'
           % (succeeded, count - succeeded))
     results.AddValue(scalar.ScalarValue(
         results.current_page, 'attempted', 'count', attempted))
     results.AddValue(scalar.ScalarValue(
         results.current_page, 'succeeded_count', 'count', count))
     results.AddValue(scalar.ScalarValue(
         results.current_page, 'succeeded_sum', 'count', succeeded))
 
+  def AddResultsForBypassOnTimeout(self, tab, results):
+    bypass_count = 0
+    tab.WaitForDocumentReadyStateToBeComplete(timeout=30)

[sclittle, 2016/08/09 21:31:31]

Is 30s long enough? Doesn't the origin site (e.g. your test page) take 60s to
respond? Wouldn't this depend on how long it would take for the proxy to timeout
and give up on the origin?

Could you also add a comment here explaining how long the timeout is expected to
be?

[Robert Ogden, 2016/08/09 21:56:22]

Comment added. 30 seconds comes out of a concern for user experience. The test
site takes 60s so that waiting 30s will force a timeout. Either way, for the
sake of the user, the proxy should bypass pretty quickly and let the user use a
direct connection.

[sclittle, 2016/08/09 22:12:03]

I'm worried about the negative case, e.g. what has to break for this test to
start failing, and how will it fail? 90s might be a better timeout here, so that
if the 60s-delayed response goes through, this might be easier to debug.

Also, >1 minute pageloads aren't uncommon on really really slow networks :). I'm
a little worried about flakiness here, e.g. we don't want the test to fail just
because the user's running on a slow network.

[Robert Ogden, 2016/08/09 22:17:55]

Good point. I'll make it 90 second timeout

+    for resp in self.IterResponses(tab):
+      if resp.HasChromeProxyViaHeader() and not resp.response.url.endswith(
+          'favicon.ico'):
+        r = resp.response
+        raise ChromeProxyMetricException, (
+            'Response for %s should not have via header after HTTP timeout.\n'
+            'Reponse: status=(%d)\nHeaders:\n %s' % (
+                r.url, r.status, r.headers))
+      elif not resp.response.url.endswith('favicon.ico'):
+        bypass_count += 1
+    if bypass_count == 0:
+      raise ChromeProxyMetricException('No pages were tested!')
+    results.AddValue(scalar.ScalarValue(
+        results.current_page, 'bypass', 'count', bypass_count))
+
 PROXIED = 'proxied'
 DIRECT = 'direct'
 
 
 class ChromeProxyVideoMetric(network_metrics.NetworkMetric):
   """Metrics for video pages.
 
   Wraps the video metrics produced by videowrapper.js, such as the video
   duration and size in pixels. Also checks a few basic HTTP response headers
   such as Content-Type and Content-Length in the video responses.
@@ skipping 112 matching lines @@
     except KeyError:
       raise ChromeProxyMetricException, 'No metrics found'
 
 # Returns whether |url| is a block-once test URL. Data Reduction Proxy has been
 # configured to always return block-once for these URLs.
 def IsTestUrlForBlockOnce(url):
   return (url == 'http://check.googlezip.net/blocksingle/' or
       url == ('http://chromeproxy-test.appspot.com/default?respBody=T0s='
               '&respHeader=eyJBY2Nlc3MtQ29udHJvbC1BbGxvdy1PcmlnaW4iOlsiKiJ'
               'dfQ==&respStatus=200&flywheelAction=block-once'))