[Telemetry] Add MeasureMemory method to action_runner

telemetry/telemetry/internal/actions/action_runner_unittest.py

Index: telemetry/telemetry/internal/actions/action_runner_unittest.py
diff --git a/telemetry/telemetry/internal/actions/action_runner_unittest.py b/telemetry/telemetry/internal/actions/action_runner_unittest.py
index a708e0efba999f2e9d5cfe5cf5a52f99b001433f..902d12c4a716824e2b7d4e9bc1e77c28d5d0ca48 100644
--- a/telemetry/telemetry/internal/actions/action_runner_unittest.py
+++ b/telemetry/telemetry/internal/actions/action_runner_unittest.py
@@ -1,6 +1,7 @@
 # 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 mock
 import unittest
 
 from telemetry.core import exceptions
@@ -8,7 +9,7 @@ from telemetry import decorators
 from telemetry.internal.actions import action_runner as action_runner_module
 from telemetry.internal.actions import page_action
 from telemetry.testing import tab_test_case
-import mock
+from telemetry.timeline import chrome_trace_category_filter
 from telemetry.timeline import model
 from telemetry.timeline import tracing_config
 from telemetry.web_perf import timeline_interaction_record as tir_module
@@ -55,6 +56,47 @@ class ActionRunnerInteractionTest(tab_test_case.TabTestCase):
     self.VerifyIssuingInteractionRecords(repeatable=True)
 
 
+class ActionRunnerMeasureMemoryTest(tab_test_case.TabTestCase):
+  def setUp(self):
+    super(ActionRunnerMeasureMemoryTest, self).setUp()
+    self.action_runner = action_runner_module.ActionRunner(self._tab,
+                                                           skip_waits=True)
+    self.Navigate('blank.html')
+
+  def testWithoutTracing(self):
+    with mock.patch.object(self._tab.browser, 'DumpMemory') as mock_method:

[nednguyen, 2016/07/08 11:15:00]

Can we not use mock here but instead assert the expected tracing event to be in
the trace when MeasureMemory is called at the right time? Even better if you
assert that the event is inside an async event that is created by console.time +
console.timeEnd

From my experience, tests that exercise code path similar to production usually
catch most problems.

[perezju, 2016/07/08 11:25:44]

Note that I'm only using mock to assert that *something is not called*. Or to
fake a "failed dump" in testWithFailedDump.

_testWithTracing below does not mock the memory dumper and we do get an actual
trace with an actual dump. As you suggest, I'll try to assert that the dump is
actually there when we expect it.

[nednguyen, 2016/07/08 11:30:37]

Oh I see. Sorry for not looking at this carefully :P
sgtm

+      self.action_runner.MeasureMemory()
+      self.assertFalse(mock_method.called)  # No-op with no tracing.
+
+  def _testWithTracing(self, deterministic_mode=False):
+    trace_memory = chrome_trace_category_filter.ChromeTraceCategoryFilter(
+        filter_string='-*,blink.console,disabled-by-default-memory-infra')
+    config = tracing_config.TracingConfig()
+    config.enable_chrome_trace = True
+    config.chrome_trace_config.SetCategoryFilter(trace_memory)
+    self._browser.platform.tracing_controller.StartTracing(config)
+    try:
+      self.action_runner.MeasureMemory(deterministic_mode)
+    finally:
+      self._browser.platform.tracing_controller.StopTracing()
+
+  def testDeterministicMode(self):
+    # Does not raise exception if dump is successful.
+    self._testWithTracing(deterministic_mode=True)
+
+  def testRealisticMode(self):
+    with mock.patch.object(
+        self.action_runner, 'ForceGarbageCollection') as mock_method:
+      self._testWithTracing(deterministic_mode=False)
+      self.assertFalse(mock_method.called)  # No forced GC in "realistic" mode.
+
+  def testWithFailedDump(self):
+    with mock.patch.object(self._tab.browser, 'DumpMemory') as mock_method:
+      mock_method.return_value = False  # Dump fails!
+      with self.assertRaises(AssertionError):
+        self._testWithTracing()
+
+
 class ActionRunnerTest(tab_test_case.TabTestCase):
   def testExecuteJavaScript(self):
     action_runner = action_runner_module.ActionRunner(self._tab,