Add UMA to report Preferences File Corruption

chrome/browser/prefs/pref_metrics_service_unittest.cc

Index: chrome/browser/prefs/pref_metrics_service_unittest.cc
diff --git a/chrome/browser/prefs/pref_metrics_service_unittest.cc b/chrome/browser/prefs/pref_metrics_service_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..3ce9994345ea21f44a2ddcadfac5a90363542443
--- /dev/null
+++ b/chrome/browser/prefs/pref_metrics_service_unittest.cc
@@ -0,0 +1,225 @@
+// Copyright (c) 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.
+
+#include "base/memory/scoped_ptr.h"
+#include "base/metrics/histogram.h"
+#include "base/metrics/statistics_recorder.h"
+#include "base/prefs/testing_pref_service.h"
+#include "base/values.h"
+#include "chrome/browser/prefs/pref_metrics_service.h"
+#include "chrome/browser/prefs/scoped_user_pref_update.h"
+#include "chrome/test/base/testing_pref_service_syncable.h"
+#include "chrome/test/base/testing_profile.h"
+#include "components/user_prefs/pref_registry_syncable.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+// The name of the dictionary pref in local state where hashes are stored.
+const char kProfilePreferenceHashes[] = "profile.preference_hashes";

[Mattias Nissler (ping if slow), 2013/08/20 12:53:54]

Use the constants defined in pref_names.{h,cc} instead.

[bbudge, 2013/08/20 18:17:50]

Done.

+
+static int preferences_checked_total;

[Mattias Nissler (ping if slow), 2013/08/20 12:53:54]

These should probably have a comment indicating that keeping these values is
necessary because there's cross-test interference (i.e. sample counts don't
reset). Also, for robustness I think it's better to make these member variables
of the test fixture and just run UpdateHistogramSamples once in SetUp() to
record the initial values when the test starts.

[bbudge, 2013/08/20 18:17:50]

Added a comment, made them member variables, and added a call in Setup(). Done.

+static int pref1_initialized_total;
+static int pref2_initialized_total;
+static int pref1_changed_total;
+static int pref2_changed_total;
+static int pref1_removed_total;
+static int pref2_removed_total;
+
+// TestingProfile may register some real preferences; to avoid interference,
+// define fake preferences for testing.
+const char* kTrackedPrefs[] = {
+  "pref_metrics_service_test.pref1",
+  "pref_metrics_service_test.pref2",
+};
+
+const int kTrackedPrefCount = arraysize(kTrackedPrefs);
+
+}  // namespace
+
+class PrefMetricsServiceTest : public testing::Test {
+ protected:
+  virtual void SetUp() {
+    preferences_checked_ = 0;
+    pref1_initialized_ = 0;
+    pref2_initialized_ = 0;
+    pref1_changed_ = 0;
+    pref2_changed_ = 0;
+    pref1_removed_ = 0;
+    pref2_removed_ = 0;
+
+    base::StatisticsRecorder::Initialize();
+
+    prefs_ = profile_.GetTestingPrefService();
+
+    // Register our test-only tracked prefs as string values.
+    for (int i = 0; i < kTrackedPrefCount; ++i) {
+      prefs_->registry()->RegisterStringPref(
+          kTrackedPrefs[i],
+          "test_default_value",
+          user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
+    }
+
+    // Initialize pref in local state that holds hashed values.
+    PrefMetricsService::RegisterPrefs(local_state_.registry());
+  }
+
+  scoped_ptr<PrefMetricsService> CreatePrefMetricsService() {
+    return scoped_ptr<PrefMetricsService>(
+        new PrefMetricsService(&profile_,
+                               &local_state_,
+                               "test_device_id",
+                               kTrackedPrefs,
+                               kTrackedPrefCount));
+  }
+
+  void GetSamples(const char* histogram_name, int* bucket1, int* bucket2) {
+    base::HistogramBase* histogram =
+        base::StatisticsRecorder::FindHistogram(histogram_name);
+    if (!histogram) {
+      *bucket1 = 0;
+      *bucket2 = 0;
+    } else {
+      scoped_ptr<base::HistogramSamples> samples(histogram->SnapshotSamples());
+      *bucket1 = samples->GetCount(0);
+      *bucket2 = samples->GetCount(1);
+    }
+  }
+
+  void UpdateHistogramSamples() {
+    int checked1, checked2;
+    GetSamples("Settings.TrackedPreferencesChecked", &checked1, &checked2);
+    EXPECT_EQ(0, checked1);
+    preferences_checked_ = checked2 - preferences_checked_total;
+    preferences_checked_total = checked2;
+
+    int inited1, inited2;
+    GetSamples("Settings.TrackedPreferenceInitialized", &inited1, &inited2);
+    pref1_initialized_ = inited1 - pref1_initialized_total;
+    pref2_initialized_ = inited2 - pref2_initialized_total;
+    pref1_initialized_total = inited1;
+    pref2_initialized_total = inited2;
+
+    int changed1, changed2;
+    GetSamples("Settings.TrackedPreferenceChanged", &changed1, &changed2);
+    pref1_changed_ = changed1 - pref1_changed_total;
+    pref2_changed_ = changed2 - pref2_changed_total;
+    pref1_changed_total = changed1;
+    pref2_changed_total = changed2;
+
+    int removed1, removed2;
+    GetSamples("Settings.TrackedPreferenceRemoved", &removed1, &removed2);
+    pref1_removed_ = removed1 - pref1_removed_total;
+    pref2_removed_ = removed2 - pref2_removed_total;
+    pref1_removed_total = removed1;
+    pref2_removed_total = removed2;
+  }
+
+  TestingProfile profile_;
+  TestingPrefServiceSyncable* prefs_;
+  TestingPrefServiceSimple local_state_;
+
+  int preferences_checked_;
+  int pref1_initialized_;
+  int pref2_initialized_;
+  int pref1_changed_;
+  int pref2_changed_;
+  int pref1_removed_;
+  int pref2_removed_;
+};
+
+TEST_F(PrefMetricsServiceTest, StartupNoUserPref) {
+  // Local state is empty and no user prefs are set. We should record that we
+  // checked preferences once but since there are no user preference values, no
+  // other histogram data should be collected.
+  scoped_ptr<PrefMetricsService> test = CreatePrefMetricsService();
+  UpdateHistogramSamples();
+  EXPECT_EQ(1, preferences_checked_);
+  EXPECT_EQ(0, pref1_initialized_);
+  EXPECT_EQ(0, pref2_initialized_);
+  EXPECT_EQ(0, pref1_changed_);
+  EXPECT_EQ(0, pref2_changed_);
+  EXPECT_EQ(0, pref1_removed_);
+  EXPECT_EQ(0, pref2_removed_);
+}
+
+TEST_F(PrefMetricsServiceTest, StartupUserPref) {
+  // Local state is empty. Set a value for one tracked pref. We should record
+  // that we checked preferences once and initialized a hash for the pref.
+  prefs_->SetString(kTrackedPrefs[0], "foo");
+  {
+    scoped_ptr<PrefMetricsService> test = CreatePrefMetricsService();
+    UpdateHistogramSamples();
+    EXPECT_EQ(1, preferences_checked_);
+    EXPECT_EQ(1, pref1_initialized_);
+    EXPECT_EQ(0, pref2_initialized_);
+    EXPECT_EQ(0, pref1_changed_);
+    EXPECT_EQ(0, pref2_changed_);
+    EXPECT_EQ(0, pref1_removed_);
+    EXPECT_EQ(0, pref2_removed_);
+
+    // Change the pref. This should be observed by the PrefMetricsService, which
+    // will update the hash in local_state_ to stay in sync.
+    prefs_->SetString(kTrackedPrefs[0], "bar");
+  }
+  // The next startup should record no changes.
+  {
+    scoped_ptr<PrefMetricsService> test = CreatePrefMetricsService();
+    UpdateHistogramSamples();
+    EXPECT_EQ(1, preferences_checked_);
+    EXPECT_EQ(0, pref1_initialized_);
+    EXPECT_EQ(0, pref2_initialized_);
+    EXPECT_EQ(0, pref1_changed_);
+    EXPECT_EQ(0, pref2_changed_);
+    EXPECT_EQ(0, pref1_removed_);
+    EXPECT_EQ(0, pref2_removed_);
+  }
+}
+
+TEST_F(PrefMetricsServiceTest, ChangedUserPref) {
+  // Local state is empty. Set a value for the tracked pref. We should record
+  // that we checked preferences once and initialized a hash for the pref.
+  prefs_->SetString(kTrackedPrefs[0], "foo");
+  {
+    scoped_ptr<PrefMetricsService> test = CreatePrefMetricsService();
+    UpdateHistogramSamples();
+    EXPECT_EQ(1, preferences_checked_);
+    EXPECT_EQ(1, pref1_initialized_);
+    EXPECT_EQ(0, pref2_initialized_);
+    EXPECT_EQ(0, pref1_changed_);
+    EXPECT_EQ(0, pref2_changed_);
+    EXPECT_EQ(0, pref1_removed_);
+    EXPECT_EQ(0, pref2_removed_);
+    // Hashed prefs should now be stored in local state.
+  }
+  // Change the value of the tracked pref while there is no PrefMetricsService
+  // to update the hash. We should observe a pref value change.
+  prefs_->SetString(kTrackedPrefs[0], "bar");
+  {
+    scoped_ptr<PrefMetricsService> test = CreatePrefMetricsService();
+    UpdateHistogramSamples();
+    EXPECT_EQ(1, preferences_checked_);
+    EXPECT_EQ(0, pref1_initialized_);
+    EXPECT_EQ(0, pref2_initialized_);
+    EXPECT_EQ(1, pref1_changed_);
+    EXPECT_EQ(0, pref2_changed_);
+    EXPECT_EQ(0, pref1_removed_);
+    EXPECT_EQ(0, pref2_removed_);
+  }
+  // Clear the value of the tracked pref while there is no PrefMetricsService
+  // to update the hash. We should observe a pref value removal.
+  prefs_->ClearPref(kTrackedPrefs[0]);
+  {
+    scoped_ptr<PrefMetricsService> test = CreatePrefMetricsService();
+    UpdateHistogramSamples();
+    EXPECT_EQ(1, preferences_checked_);
+    EXPECT_EQ(0, pref1_initialized_);
+    EXPECT_EQ(0, pref2_initialized_);
+    EXPECT_EQ(0, pref1_changed_);
+    EXPECT_EQ(0, pref2_changed_);
+    EXPECT_EQ(1, pref1_removed_);
+    EXPECT_EQ(0, pref2_removed_);
+  }
+}
+

[Mattias Nissler (ping if slow), 2013/08/20 12:53:54]

nit: remove trailing newline.

[bbudge, 2013/08/20 18:17:50]

Done.