telemetry: Create a helper class to quickly extend profiles.

tools/perf/profile_creators/fast_navigation_profile_extender_unittest.py

+# Copyright 2015 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 profile_creators.fast_navigation_profile_extender import (
+    FastNavigationProfileExtender)
+from telemetry.core import util
+
+util.AddDirToPythonPath(util.GetTelemetryDir(), 'third_party', 'mock')
+import mock
+
+
+class FakeTab(object):
+  pass
+
+
+class FakeBrowser(object):
+  def __init__(self, tab_count):
+    self.tabs = []
+    for _ in range(tab_count):
+      self.tabs.append(FakeTab())
+
+
+# Testing private method.
+# pylint: disable=W0212
+class FastNavigationProfileExtenderTest(unittest.TestCase):
+  def testPerformNavigations(self):
+    extender = FastNavigationProfileExtender()
+    num_urls = extender._NUM_PARALLEL_PAGES * 3 + 4
+    num_tabs = extender._NUM_TABS
+
+    navigation_urls = []
+    for i in range(num_urls):
+      navigation_urls.append('http://test%s.com' % i)
+
+    extender._navigation_urls = navigation_urls
+    extender._browser = FakeBrowser(num_tabs)
+    extender._BatchNavigateTabs = mock.MagicMock()
+
+    # Set up a callback to record the tabs and urls in each navigation.
+    batch_callback_tabs = []
+    batch_callback_urls = []
+    def SideEffect(*args, **_):
+      batch = args[0]
+      for tab, url in batch:
+        batch_callback_tabs.append(tab)
+        batch_callback_urls.append(url)
+    extender._BatchNavigateTabs.side_effect = SideEffect
+
+    # Perform the navigations.
+    extender._PerformNavigations()
+
+    # Each url should have been navigated to exactly once.
+    self.assertEqual(set(batch_callback_urls), set(navigation_urls))
+
+    # The first 4 tabs should have been navigated 4 times. The remaining tabs
+    # should have been navigated 3 times.
+    num_navigations_per_tab = 3
+    num_tabs_with_one_extra_navigation = 4
+    for i in range(len(extender._browser.tabs)):
+      tab = extender._browser.tabs[i]
+
+      expected_tab_navigation_count = num_navigations_per_tab
+      if i < num_tabs_with_one_extra_navigation:
+        expected_tab_navigation_count += 1
+
+      count = batch_callback_tabs.count(tab)
+      self.assertEqual(count, expected_tab_navigation_count)