[Sync] Initial implementation of foreign sessions suggestions provider.

components/ntp_snippets/sessions/foreign_sessions_suggestions_provider_unittest.cc

Index: components/ntp_snippets/sessions/foreign_sessions_suggestions_provider_unittest.cc
diff --git a/components/ntp_snippets/sessions/foreign_sessions_suggestions_provider_unittest.cc b/components/ntp_snippets/sessions/foreign_sessions_suggestions_provider_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ae22beb73c57d8dd50b8f246a1ab74286b3e0a9a
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+++ b/components/ntp_snippets/sessions/foreign_sessions_suggestions_provider_unittest.cc
@@ -0,0 +1,328 @@
+// Copyright 2016 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 "components/ntp_snippets/sessions/foreign_sessions_suggestions_provider.h"
+
+#include <map>
+#include <utility>
+
+#include "base/callback_forward.h"
+#include "base/memory/ptr_util.h"
+#include "base/strings/string_number_conversions.h"
+#include "components/ntp_snippets/category.h"
+#include "components/ntp_snippets/category_factory.h"
+#include "components/ntp_snippets/content_suggestions_provider.h"
+#include "components/ntp_snippets/mock_content_suggestions_provider_observer.h"
+#include "components/prefs/testing_pref_service.h"
+#include "components/sessions/core/serialized_navigation_entry.h"
+#include "components/sessions/core/serialized_navigation_entry_test_helper.h"
+#include "components/sessions/core/session_types.h"
+#include "components/sync_sessions/synced_session.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using base::Time;
+using base::TimeDelta;
+using sessions::SerializedNavigationEntry;
+using sessions::SessionTab;
+using sessions::SessionWindow;
+using sync_sessions::SyncedSession;
+using testing::ElementsAre;
+using testing::IsEmpty;
+using testing::Property;
+using testing::Test;
+using testing::UnorderedElementsAre;
+using testing::_;
+
+namespace ntp_snippets {
+namespace {
+
+const char kUrl1[] = "http://www.fake1.com/";
+const char kUrl2[] = "http://www.fake2.com/";
+const char kUrl3[] = "http://www.fake3.com/";
+const char kUrl4[] = "http://www.fake4.com/";
+const char kUrl5[] = "http://www.fake5.com/";
+const char kUrl6[] = "http://www.fake6.com/";
+const char kUrl7[] = "http://www.fake7.com/";
+const char kUrl8[] = "http://www.fake8.com/";
+const char kUrl9[] = "http://www.fake9.com/";
+const char kUrl10[] = "http://www.fake10.com/";
+const char kUrl11[] = "http://www.fake11.com/";
+const char kTitle[] = "title is ignored";
+
+SessionWindow* GetOrCreateWindow(SyncedSession* session, int window_id) {
+  if (session->windows.find(window_id) == session->windows.end()) {
+    // The session deletes the windows it points at upon destruction.
+    session->windows[window_id] = new SessionWindow();
+  }
+  return session->windows[window_id];
+}
+
+void AddTabToSession(SyncedSession* session,
+                     int window_id,
+                     const std::string& url,
+                     TimeDelta age) {
+  SerializedNavigationEntry navigation =
+      sessions::SerializedNavigationEntryTestHelper::CreateNavigation(url,
+                                                                      kTitle);
+
+  std::unique_ptr<SessionTab> tab = base::MakeUnique<SessionTab>();
+  tab->timestamp = Time::Now() - age;
+  tab->navigations.push_back(navigation);
+
+  SessionWindow* window = GetOrCreateWindow(session, window_id);
+  // The window deletes the tabs it points at upon destruction.
+  window->tabs.push_back(tab.release());
+}
+
+class FakeForeignSessionsProvider : public ForeignSessionsProvider {
+ public:
+  ~FakeForeignSessionsProvider() override {}
+  void SetAllForeignSessions(std::vector<const SyncedSession*> sessions) {
+    sessions_ = sessions;
+    change_callback_.Run();
+  }
+
+  // ForeignSessionsProvider implementation.
+  void SubscribeForForeignTabChange(
+      const base::Closure& change_callback) override {
+    change_callback_ = change_callback;
+  }
+  bool HasSessionsData() override { return true; }
+  std::vector<const sync_sessions::SyncedSession*> GetAllForeignSessions()
+      override {
+    return sessions_;
+  }
+
+ private:
+  std::vector<const SyncedSession*> sessions_;
+  base::Closure change_callback_;
+};
+}  // namespace
+
+class ForeignSessionsSuggestionsProviderTest : public Test {
+ public:
+  ForeignSessionsSuggestionsProviderTest() {
+    ForeignSessionsSuggestionsProvider::RegisterProfilePrefs(
+        pref_service_.registry());
+
+    std::unique_ptr<FakeForeignSessionsProvider>
+        fake_foreign_sessions_provider =
+            base::MakeUnique<FakeForeignSessionsProvider>();
+    fake_foreign_sessions_provider_ = fake_foreign_sessions_provider.get();
+
+    // During the provider's construction the following mock calls occur.
+    EXPECT_CALL(*observer(), OnNewSuggestions(_, category(), IsEmpty()));
+    EXPECT_CALL(*observer(), OnCategoryStatusChanged(
+                                 _, category(), CategoryStatus::AVAILABLE));
+
+    provider_ = base::MakeUnique<ForeignSessionsSuggestionsProvider>(
+        &observer_, &category_factory_,
+        std::move(fake_foreign_sessions_provider), &pref_service_);
+  }
+
+ protected:
+  SyncedSession* GetOrCreateSession(int session_id) {
+    if (sessions_map_.find(session_id) == sessions_map_.end()) {
+      std::string id_as_string = base::IntToString(session_id);
+      std::unique_ptr<SyncedSession> owned_session =
+          base::MakeUnique<SyncedSession>();
+      owned_session->session_tag = id_as_string;
+      owned_session->session_name = id_as_string;
+      sessions_map_[session_id] = std::move(owned_session);
+    }
+    return sessions_map_[session_id].get();
+  }
+
+  void AddTab(int session_id,
+              int window_id,
+              const std::string& url,
+              TimeDelta age) {
+    AddTabToSession(GetOrCreateSession(session_id), window_id, url, age);
+  }
+
+  void TriggerOnChange() {
+    std::vector<const SyncedSession*> sessions;
+    for (const auto& kv : sessions_map_) {
+      sessions.push_back(kv.second.get());
+    }
+    fake_foreign_sessions_provider_->SetAllForeignSessions(sessions);
+  }
+
+  void Dismiss(const std::string& url) {
+    // The url of a given suggestion is used as the |within_category_id|.
+    provider_->DismissSuggestion(provider_->MakeUniqueID(category(), url));
+  }
+
+  Category category() {
+    return category_factory_.FromKnownCategory(KnownCategories::FOREIGN_TABS);
+  }
+
+  MockContentSuggestionsProviderObserver* observer() { return &observer_; }
+
+ private:
+  FakeForeignSessionsProvider* fake_foreign_sessions_provider_;
+  MockContentSuggestionsProviderObserver observer_;
+  CategoryFactory category_factory_;
+  TestingPrefServiceSimple pref_service_;
+  std::unique_ptr<ForeignSessionsSuggestionsProvider> provider_;
+  std::map<int, std::unique_ptr<SyncedSession>> sessions_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(ForeignSessionsSuggestionsProviderTest);
+};
+
+TEST_F(ForeignSessionsSuggestionsProviderTest, Empty) {
+  // When no sessions data is added, expect no suggestions.
+  EXPECT_CALL(*observer(), OnNewSuggestions(_, category(), IsEmpty()));
+  TriggerOnChange();
+}
+
+TEST_F(ForeignSessionsSuggestionsProviderTest, Single) {
+  // Expect a single valid tab because that is what has been added.
+  EXPECT_CALL(*observer(),
+              OnNewSuggestions(
+                  _, category(),
+                  ElementsAre(Property(&ContentSuggestion::url, GURL(kUrl1)))));
+  AddTab(0, 0, kUrl1, TimeDelta::FromMinutes(1));
+  TriggerOnChange();
+}
+
+TEST_F(ForeignSessionsSuggestionsProviderTest, Old) {
+  // The only sessions data is too old to be suggested, so expect empty.
+  EXPECT_CALL(*observer(), OnNewSuggestions(_, category(), IsEmpty()));
+  AddTab(0, 0, kUrl1, TimeDelta::FromHours(4));
+  TriggerOnChange();
+}
+
+TEST_F(ForeignSessionsSuggestionsProviderTest, Ordered) {
+  // Suggestions ordering should be in reverse chronological order, or youngest
+  // first.
+  EXPECT_CALL(*observer(),
+              OnNewSuggestions(
+                  _, category(),
+                  ElementsAre(Property(&ContentSuggestion::url, GURL(kUrl1)),
+                              Property(&ContentSuggestion::url, GURL(kUrl2)),
+                              Property(&ContentSuggestion::url, GURL(kUrl3)),
+                              Property(&ContentSuggestion::url, GURL(kUrl4)))));
+  AddTab(0, 0, kUrl2, TimeDelta::FromMinutes(2));
+  AddTab(0, 0, kUrl4, TimeDelta::FromMinutes(4));
+  AddTab(0, 1, kUrl3, TimeDelta::FromMinutes(3));
+  AddTab(1, 0, kUrl1, TimeDelta::FromMinutes(1));
+  TriggerOnChange();
+}
+
+TEST_F(ForeignSessionsSuggestionsProviderTest, MaxPerDevice) {
+  // Each device, which is to equivalent a unique |session_tag|, has a limit to
+  // the number of suggestions it is allowed to contribute. Here all four
+  // suggestions are within the recency threshold, but only three are allowed
+  // per device. As such, expect that the oldest of the four will not be
+  // suggested.
+  EXPECT_CALL(*observer(),
+              OnNewSuggestions(
+                  _, category(),
+                  ElementsAre(Property(&ContentSuggestion::url, GURL(kUrl1)),
+                              Property(&ContentSuggestion::url, GURL(kUrl2)),
+                              Property(&ContentSuggestion::url, GURL(kUrl3)))));
+  AddTab(0, 0, kUrl1, TimeDelta::FromMinutes(1));
+  AddTab(0, 0, kUrl2, TimeDelta::FromMinutes(2));
+  AddTab(0, 0, kUrl3, TimeDelta::FromMinutes(3));
+  AddTab(0, 0, kUrl4, TimeDelta::FromMinutes(4));
+  TriggerOnChange();
+}
+
+TEST_F(ForeignSessionsSuggestionsProviderTest, MaxTotal) {
+  // There's a limit to the total nubmer of suggestions that the provider will
+  // ever return, which should be ten. Here there are eleven valid suggestion
+  // entries, spread out over multiple devices/sessions to avoid the per device
+  // cutoff. Expect that the least recent of the eleven to be dropped.
+  EXPECT_CALL(
+      *observer(),
+      OnNewSuggestions(
+          _, category(),
+          ElementsAre(Property(&ContentSuggestion::url, GURL(kUrl1)),
+                      Property(&ContentSuggestion::url, GURL(kUrl2)),
+                      Property(&ContentSuggestion::url, GURL(kUrl3)),
+                      Property(&ContentSuggestion::url, GURL(kUrl4)),
+                      Property(&ContentSuggestion::url, GURL(kUrl5)),
+                      Property(&ContentSuggestion::url, GURL(kUrl6)),
+                      Property(&ContentSuggestion::url, GURL(kUrl7)),
+                      Property(&ContentSuggestion::url, GURL(kUrl8)),
+                      Property(&ContentSuggestion::url, GURL(kUrl9)),
+                      Property(&ContentSuggestion::url, GURL(kUrl10)))));
+  AddTab(0, 0, kUrl1, TimeDelta::FromMinutes(1));
+  AddTab(0, 0, kUrl2, TimeDelta::FromMinutes(2));
+  AddTab(0, 0, kUrl3, TimeDelta::FromMinutes(3));
+  AddTab(1, 0, kUrl4, TimeDelta::FromMinutes(4));
+  AddTab(1, 0, kUrl5, TimeDelta::FromMinutes(5));
+  AddTab(1, 0, kUrl6, TimeDelta::FromMinutes(6));
+  AddTab(2, 0, kUrl7, TimeDelta::FromMinutes(7));
+  AddTab(2, 0, kUrl8, TimeDelta::FromMinutes(8));
+  AddTab(2, 0, kUrl9, TimeDelta::FromMinutes(9));
+  AddTab(3, 0, kUrl10, TimeDelta::FromMinutes(10));
+  AddTab(3, 0, kUrl11, TimeDelta::FromMinutes(11));
+  TriggerOnChange();
+}
+
+TEST_F(ForeignSessionsSuggestionsProviderTest, Duplicates) {
+  // The same url is never suggested more than once at a time. All the session
+  // data has the same url so only expect a single suggestion.
+  EXPECT_CALL(*observer(),
+              OnNewSuggestions(
+                  _, category(),
+                  ElementsAre(Property(&ContentSuggestion::url, GURL(kUrl1)))));
+  AddTab(0, 0, kUrl1, TimeDelta::FromMinutes(1));
+  AddTab(0, 1, kUrl1, TimeDelta::FromMinutes(2));
+  AddTab(1, 1, kUrl1, TimeDelta::FromMinutes(3));
+  TriggerOnChange();
+}
+
+TEST_F(ForeignSessionsSuggestionsProviderTest, DuplicatesChangingOtherSession) {
+  // Normally |kUrl4| wouldn't show up, because session_id=0 already has 3
+  // younger tabs, but session_id=1 has a younger |kUrl3| which gives |kUrl4| a
+  // spot.
+  EXPECT_CALL(*observer(),
+              OnNewSuggestions(
+                  _, category(),
+                  ElementsAre(Property(&ContentSuggestion::url, GURL(kUrl3)),
+                              Property(&ContentSuggestion::url, GURL(kUrl1)),
+                              Property(&ContentSuggestion::url, GURL(kUrl2)),
+                              Property(&ContentSuggestion::url, GURL(kUrl4)))));
+  AddTab(0, 0, kUrl1, TimeDelta::FromMinutes(1));
+  AddTab(0, 0, kUrl2, TimeDelta::FromMinutes(2));
+  AddTab(0, 0, kUrl3, TimeDelta::FromMinutes(3));
+  AddTab(0, 0, kUrl4, TimeDelta::FromMinutes(4));
+  AddTab(1, 0, kUrl3, TimeDelta::FromMinutes(0));
+  TriggerOnChange();
+}
+
+TEST_F(ForeignSessionsSuggestionsProviderTest, Dismissed) {
+  // Dimissed urls should not be suggested.
+  EXPECT_CALL(*observer(), OnNewSuggestions(_, category(), IsEmpty()));
+  Dismiss(kUrl1);
+  AddTab(0, 0, kUrl1, TimeDelta::FromMinutes(1));
+  TriggerOnChange();
+}
+
+TEST_F(ForeignSessionsSuggestionsProviderTest, DismissedChangingOwnSession) {
+  // Similar to DuplicatesChangingOtherSession, without dismissals we would
+  // expect urls 1-3. However, because of dismissals we reach all the down to
+  // |kUrl5| before the per device cutoff is hit.
+  EXPECT_CALL(*observer(),
+              OnNewSuggestions(
+                  _, category(),
+                  ElementsAre(Property(&ContentSuggestion::url, GURL(kUrl2)),
+                              Property(&ContentSuggestion::url, GURL(kUrl3)),
+                              Property(&ContentSuggestion::url, GURL(kUrl5)))));
+  Dismiss(kUrl1);
+  Dismiss(kUrl4);
+  AddTab(0, 0, kUrl1, TimeDelta::FromMinutes(1));
+  AddTab(0, 0, kUrl2, TimeDelta::FromMinutes(2));
+  AddTab(0, 0, kUrl3, TimeDelta::FromMinutes(3));
+  AddTab(0, 0, kUrl4, TimeDelta::FromMinutes(4));
+  AddTab(0, 0, kUrl5, TimeDelta::FromMinutes(5));
+  AddTab(0, 0, kUrl6, TimeDelta::FromMinutes(6));
+  TriggerOnChange();
+}
+
+}  // namespace ntp_snippets