[NTP Snippets] Refactor background scheduling for remote suggestions

components/ntp_snippets/remote/remote_suggestions_scheduler_unittest.cc

Index: components/ntp_snippets/remote/remote_suggestions_scheduler_unittest.cc
diff --git a/components/ntp_snippets/remote/remote_suggestions_scheduler_unittest.cc b/components/ntp_snippets/remote/remote_suggestions_scheduler_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..1bf9caed0eb06270172339cc4aadf9141799bd36
--- /dev/null
+++ b/components/ntp_snippets/remote/remote_suggestions_scheduler_unittest.cc
@@ -0,0 +1,242 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.

[Marc Treib, 2016/12/09 12:25:27]

2016

[jkrcal, 2016/12/19 09:40:23]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/ntp_snippets/remote/remote_suggestions_scheduler.h"
+
+#include <memory>
+#include <set>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "base/command_line.h"
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "base/time/time.h"
+#include "components/ntp_snippets/features.h"
+#include "components/ntp_snippets/ntp_snippets_constants.h"
+#include "components/ntp_snippets/pref_names.h"
+#include "components/ntp_snippets/remote/remote_suggestions_hard_scheduler.h"
+#include "components/ntp_snippets/remote/test_utils.h"
+#include "components/ntp_snippets/user_classifier.h"
+#include "components/prefs/testing_pref_service.h"
+#include "components/variations/variations_params_manager.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using testing::ElementsAre;
+using testing::Eq;
+using testing::InSequence;
+using testing::Invoke;
+using testing::IsEmpty;
+using testing::Mock;
+using testing::MockFunction;
+using testing::NiceMock;
+using testing::Not;
+using testing::SaveArg;
+using testing::SizeIs;
+using testing::StartsWith;
+using testing::WithArgs;
+using testing::_;
+
+namespace ntp_snippets {
+
+namespace {
+
+const char* kDifferentWiFiInterval = "2";
+
+class MockHardScheduler : public RemoteSuggestionsHardScheduler {
+ public:
+  MOCK_METHOD2(Schedule,
+               bool(base::TimeDelta period_wifi,
+                    base::TimeDelta period_fallback));
+  MOCK_METHOD0(Unschedule, bool());
+};
+
+class MockUpdater : public RemoteSuggestionsScheduler::Updater {
+ public:
+  MOCK_METHOD0(UpdateRemoteSuggestionsBySchedule, void());
+};
+
+}  // namespace
+
+class RemoteSuggestionsSchedulerTest : public ::testing::Test {
+ public:
+  RemoteSuggestionsSchedulerTest()
+      : user_classifier_(/*pref_service=*/nullptr) {
+    RemoteSuggestionsScheduler::RegisterProfilePrefs(
+        utils_.pref_service()->registry());
+  }
+
+  std::unique_ptr<RemoteSuggestionsScheduler> MakeScheduler(bool enabled) {
+    auto scheduler = base::MakeUnique<RemoteSuggestionsScheduler>(
+        &mock_scheduler(), &user_classifier_, utils_.pref_service());
+
+    scheduler->SetUpdater(&updater());
+
+    if (enabled) {

[Marc Treib, 2016/12/09 12:25:27]

Hm. Might be better to do this in the individual tests directly - WDYT?

+      scheduler->Schedule();
+    } else {
+      scheduler->Unschedule();
+    }
+    return scheduler;
+  }
+
+ protected:
+  MockHardScheduler& mock_scheduler() { return hard_scheduler_; }

[Marc Treib, 2016/12/09 12:25:27]

Please rename, otherwise it's difficult to keep the two "schedulers" apart. (Per
the other comment, maybe this class should be renamed anyway.)

Non-const references are discouraged at best in Chromium, so maybe return
pointers instead?

[jkrcal, 2016/12/19 09:40:23]

Done.

+  MockUpdater& updater() { return updater_; }
+
+ private:
+  test::RemoteSuggestionsTestUtils utils_;
+  UserClassifier user_classifier_;
+  NiceMock<MockHardScheduler> hard_scheduler_;
+  NiceMock<MockUpdater> updater_;
+
+  DISALLOW_COPY_AND_ASSIGN(RemoteSuggestionsSchedulerTest);
+};
+
+TEST_F(RemoteSuggestionsSchedulerTest, SchedulesOnStart) {
+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);
+  EXPECT_CALL(mock_scheduler(), Unschedule()).Times(0);
+
+  auto scheduler = MakeScheduler(/*enabled=*/true);
+}
+
+TEST_F(RemoteSuggestionsSchedulerTest, UnschedulesAfterBeingScheduled) {
+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);

[Marc Treib, 2016/12/09 12:25:27]

Probably you mostly copy-pasted this code, but: Times(1) is the default, so no
need to specify, unless it's really crucial to this test.

[jkrcal, 2016/12/19 09:40:23]

Done.

+  auto scheduler = MakeScheduler(/*enabled=*/true);
+
+  Mock::VerifyAndClearExpectations(&mock_scheduler());

[Marc Treib, 2016/12/09 12:25:27]

FYI: Tim considers VerifyAndClearExpectations an anti-pattern, though in this
case it seems okay to me. I guess an alternative would be testing::InSequence,
which would however provide slightly less strict guarantees here.

+  EXPECT_CALL(mock_scheduler(), Unschedule()).Times(1);
+  scheduler->Unschedule();
+}
+
+TEST_F(RemoteSuggestionsSchedulerTest, DoesNotUnscheduleOnShutdown) {
+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);
+  EXPECT_CALL(mock_scheduler(), Unschedule()).Times(0);
+
+  auto scheduler = MakeScheduler(/*enabled=*/true);
+
+  scheduler.reset();

[Marc Treib, 2016/12/09 12:25:27]

Not really necessary; it'll go out of scope anyway. Maybe worth a comment
though?

[jkrcal, 2016/12/19 09:40:24]

Done.

+}
+
+TEST_F(RemoteSuggestionsSchedulerTest, UnscheduleOnlyOnce) {

[Marc Treib, 2016/12/09 12:25:27]

nitty nit: UnschedulesOnlyOnce (add an "s")

[jkrcal, 2016/12/19 09:40:23]

Done.

+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);
+  auto scheduler = MakeScheduler(/*enabled=*/true);
+
+  // Unschedule for the first time.
+  Mock::VerifyAndClearExpectations(&mock_scheduler());
+  EXPECT_CALL(mock_scheduler(), Unschedule()).Times(1);
+  scheduler->Unschedule();
+
+  // When unscheduling again, we should not get any |Schedule| calls:
+  // The tasks are already unscheduled, so no need to do it again.
+  Mock::VerifyAndClearExpectations(&mock_scheduler());
+  EXPECT_CALL(mock_scheduler(), Unschedule()).Times(0);
+  scheduler->Unschedule();
+}
+
+TEST_F(RemoteSuggestionsSchedulerTest, ScheduleOnlyOnce) {

[Marc Treib, 2016/12/09 12:25:27]

Also here: +s (and a few more below)

[jkrcal, 2016/12/19 09:40:23]

Done.

+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);
+
+  auto scheduler = MakeScheduler(/*enabled=*/true);
+
+  // When scheduling again, we should not get any |Schedule| calls:
+  // The tasks are already scheduled with the correct intervals, so no need to
+  // do it again.
+  Mock::VerifyAndClearExpectations(&mock_scheduler());
+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(0);
+  scheduler->Schedule();
+}
+
+TEST_F(RemoteSuggestionsSchedulerTest, RescheduleWhenWifiParamChanges) {
+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);
+  auto scheduler = MakeScheduler(/*enabled=*/true);
+
+  // UserClassifier defaults to UserClass::ACTIVE_NTP_USER if PrefService is
+  // null. Change the wifi interval for this class.
+  variations::testing::VariationParamsManager params_manager(
+      ntp_snippets::kStudyName,
+      {{"fetching_interval_hours-wifi-active_ntp_user",
+        kDifferentWiFiInterval}},
+      {kArticleSuggestionsFeature.name});
+
+  Mock::VerifyAndClearExpectations(&mock_scheduler());
+  // After the change of a paramter, it should reschedule.
+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);
+  scheduler->Schedule();
+}
+
+TEST_F(RemoteSuggestionsSchedulerTest, RescheduleWhenFallbackParamChanges) {
+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);
+  auto scheduler = MakeScheduler(/*enabled=*/true);
+
+  // UserClassifier defaults to UserClass::ACTIVE_NTP_USER if PrefService is
+  // null. Change the wifi interval for this class.
+  variations::testing::VariationParamsManager params_manager(
+      ntp_snippets::kStudyName,
+      {{"fetching_interval_hours-fallback-active_ntp_user",
+        kDifferentWiFiInterval}},
+      {kArticleSuggestionsFeature.name});
+
+  Mock::VerifyAndClearExpectations(&mock_scheduler());
+  // After the change of a paramter, it should reschedule.
+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);
+  scheduler->Schedule();
+}
+
+TEST_F(RemoteSuggestionsSchedulerTest, HandlesForcedReschedules) {
+  {
+    InSequence s;
+    // The initial scheduling.
+    EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);
+    // Forced rescheduling.
+    EXPECT_CALL(mock_scheduler(), Unschedule()).Times(1);
+    EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);
+  }
+
+  auto scheduler = MakeScheduler(/*enabled=*/true);
+  // Forced reschedule
+  scheduler->Unschedule();
+  scheduler->Schedule();
+}
+
+TEST_F(RemoteSuggestionsSchedulerTest, ReschedulesAfterSuccessfulUpdate) {
+  // The initial scheduling.
+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);
+  auto scheduler = MakeScheduler(/*enabled=*/true);
+  Mock::VerifyAndClearExpectations(&mock_scheduler());
+
+  // Simulate a succesfull update.

[Marc Treib, 2016/12/09 12:25:27]

nitty nit: successful (only one "l")

[jkrcal, 2016/12/19 09:40:23]

Done.

+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);
+  scheduler->PerformHardUpdate();
+  scheduler->OnSuccessfulUpdate();

[Marc Treib, 2016/12/09 12:25:27]

Why do we need both of these calls?
OnSuccessfulUpdate should really be called by the updater, right? So maybe a
Fake implementation of that would be the right choice here?

[jkrcal, 2016/12/19 09:40:23]

Done.

+}
+
+TEST_F(RemoteSuggestionsSchedulerTest, DoesNotRescheduleAfterFailedUpdate) {
+  // The initial scheduling.
+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);
+  auto scheduler = MakeScheduler(/*enabled=*/true);
+  Mock::VerifyAndClearExpectations(&mock_scheduler());
+
+  // Simulate a succesfull update.
+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(0);
+  scheduler->PerformHardUpdate();
+  // Failed -> do not call OnSuccessfulUpdate().
+}
+
+TEST_F(RemoteSuggestionsSchedulerTest, CallsUpdater) {
+  // The initial scheduling.
+  EXPECT_CALL(mock_scheduler(), Schedule(_, _)).Times(1);
+  auto scheduler = MakeScheduler(/*enabled=*/true);
+
+  // Simulate a succesfull update.
+  EXPECT_CALL(updater(), UpdateRemoteSuggestionsBySchedule()).Times(1);
+  scheduler->PerformHardUpdate();
+}
+
+}  // namespace ntp_snippets