Only show Last N Pages in the UI when the corresponding tab is visible.

components/ntp_snippets/offline_pages/recent_tab_suggestions_provider_unittest.cc

Index: components/ntp_snippets/offline_pages/recent_tab_suggestions_provider_unittest.cc
diff --git a/components/ntp_snippets/offline_pages/recent_tab_suggestions_provider_unittest.cc b/components/ntp_snippets/offline_pages/recent_tab_suggestions_provider_unittest.cc
index bc3d6d2f7f00a875bb94981200df1a53a62c2228..ea89b2422c963cafc4d13a56c56a8a667b96ebf4 100644
--- a/components/ntp_snippets/offline_pages/recent_tab_suggestions_provider_unittest.cc
+++ b/components/ntp_snippets/offline_pages/recent_tab_suggestions_provider_unittest.cc
@@ -10,14 +10,18 @@
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/test/test_simple_task_runner.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
 #include "components/ntp_snippets/category.h"
 #include "components/ntp_snippets/content_suggestions_provider.h"
 #include "components/ntp_snippets/mock_content_suggestions_provider_observer.h"
 #include "components/ntp_snippets/offline_pages/offline_pages_test_utils.h"
+#include "components/offline_pages/core/background/request_coordinator_stub_taco.h"
 #include "components/offline_pages/core/client_namespace_constants.h"
+#include "components/offline_pages/core/downloads/download_ui_adapter.h"
 #include "components/offline_pages/core/offline_page_item.h"
-#include "components/offline_pages/core/stub_offline_page_model.h"
+#include "components/offline_pages/core/recent_tabs/recent_tabs_ui_adapter_delegate.h"
 #include "components/prefs/testing_pref_service.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -27,7 +31,6 @@ using ntp_snippets::test::FakeOfflinePageModel;
 using offline_pages::ClientId;
 using offline_pages::MultipleOfflinePageItemCallback;
 using offline_pages::OfflinePageItem;
-using offline_pages::StubOfflinePageModel;
 using testing::_;
 using testing::IsEmpty;
 using testing::Mock;
@@ -38,11 +41,14 @@ namespace ntp_snippets {
 
 namespace {
 
-OfflinePageItem CreateDummyRecentTab(int id) {
-  OfflinePageItem item =
-      test::CreateDummyOfflinePageItem(id, offline_pages::kLastNNamespace);
-  item.client_id.id = base::IntToString(id);
-  return item;
+OfflinePageItem CreateDummyRecentTab(int offline_id) {
+  // This is used to assign unique tab IDs to pages.  Since offline IDs are
+  // typically small integers like 1, 2, 3 etc, we start at 1001 to ensure that
+  // they are different, and can catch bugs where offline page ID is used in
+  // place of tab ID and vice versa.
+  std::string tab_id = base::IntToString(offline_id + 1000);
+  ClientId client_id(offline_pages::kLastNNamespace, tab_id);
+  return test::CreateDummyOfflinePageItem(offline_id, client_id);
 }
 
 std::vector<OfflinePageItem> CreateDummyRecentTabs(
@@ -63,15 +69,25 @@ OfflinePageItem CreateDummyRecentTab(int id, base::Time time) {
 
 }  // namespace
 
-class RecentTabSuggestionsProviderTest : public testing::Test {
+class RecentTabSuggestionsProviderTestNoLoad : public testing::Test {
  public:
-  RecentTabSuggestionsProviderTest()
-      : pref_service_(new TestingPrefServiceSimple()) {
+  RecentTabSuggestionsProviderTestNoLoad()
+      : task_runner_(new base::TestSimpleTaskRunner()),
+        task_runner_handle_(task_runner_),
+        pref_service_(new TestingPrefServiceSimple()) {
     RecentTabSuggestionsProvider::RegisterProfilePrefs(
         pref_service()->registry());
 
-    provider_.reset(
-        new RecentTabSuggestionsProvider(&observer_, &model_, pref_service()));
+    taco_ = base::MakeUnique<offline_pages::RequestCoordinatorStubTaco>();
+    taco_->CreateRequestCoordinator();
+
+    ui_adapter_ = offline_pages::RecentTabsUIAdapterDelegate::
+        GetOrCreateRecentTabsUIAdapter(&model_, taco_->request_coordinator());
+    delegate_ =
+        offline_pages::RecentTabsUIAdapterDelegate::FromDownloadUIAdapter(
+            ui_adapter_);
+    provider_ = base::MakeUnique<RecentTabSuggestionsProvider>(
+        &observer_, ui_adapter_, pref_service());
   }
 
   Category recent_tabs_category() {
@@ -82,18 +98,25 @@ class RecentTabSuggestionsProviderTest : public testing::Test {
     return ContentSuggestion::ID(recent_tabs_category(), base::IntToString(id));
   }
 
+  void AddTabAndOfflinePageToModel(const OfflinePageItem& item) {
+    AddTab(offline_pages::RecentTabsUIAdapterDelegate::TabIdFromClientId(
+        item.client_id));
+    AddOfflinePageToModel(item);
+  }
+
+  void AddTab(int tab_id) { delegate_->RegisterTab(tab_id); }
+
+  void RemoveTab(int tab_id) { delegate_->UnregisterTab(tab_id); }
+
   void AddOfflinePageToModel(const OfflinePageItem& item) {
-    model_.mutable_items()->push_back(item);
-    provider_->OfflinePageAdded(&model_, item);
+    ui_adapter_->OfflinePageAdded(&model_, item);
   }
 
   void FireOfflinePageDeleted(const OfflinePageItem& item) {
-    auto iter = std::remove(model_.mutable_items()->begin(),
-                            model_.mutable_items()->end(), item);
-    auto end = model_.mutable_items()->end();
-    model_.mutable_items()->erase(iter, end);
-
-    provider_->OfflinePageDeleted(item.offline_id, item.client_id);
+    int tab_id = offline_pages::RecentTabsUIAdapterDelegate::TabIdFromClientId(
+        item.client_id);
+    RemoveTab(tab_id);
+    ui_adapter_->OfflinePageDeleted(item.offline_id, item.client_id);
   }
 
   std::set<std::string> ReadDismissedIDsFromPrefs() {
@@ -101,26 +124,45 @@ class RecentTabSuggestionsProviderTest : public testing::Test {
   }
 
   RecentTabSuggestionsProvider* provider() { return provider_.get(); }
-  FakeOfflinePageModel* model() { return &model_; }
   MockContentSuggestionsProviderObserver* observer() { return &observer_; }
   TestingPrefServiceSimple* pref_service() { return pref_service_.get(); }
+  base::TestSimpleTaskRunner* task_runner() { return task_runner_.get(); }
 
  private:
   FakeOfflinePageModel model_;
+  offline_pages::DownloadUIAdapter* ui_adapter_;
+  offline_pages::RecentTabsUIAdapterDelegate* delegate_;
+  scoped_refptr<base::TestSimpleTaskRunner> task_runner_;
+  base::ThreadTaskRunnerHandle task_runner_handle_;
+  std::unique_ptr<offline_pages::RequestCoordinatorStubTaco> taco_;
   MockContentSuggestionsProviderObserver observer_;
   std::unique_ptr<TestingPrefServiceSimple> pref_service_;
   // Last so that the dependencies are deleted after the provider.
   std::unique_ptr<RecentTabSuggestionsProvider> provider_;
 
+  DISALLOW_COPY_AND_ASSIGN(RecentTabSuggestionsProviderTestNoLoad);
+};
+
+// Test that always loads the model before the start of the test.
+class RecentTabSuggestionsProviderTest
+    : public RecentTabSuggestionsProviderTestNoLoad {
+ public:
+  RecentTabSuggestionsProviderTest() = default;
+
+  void SetUp() override {
+    // The UI adapter always fires asynchronously upon loading, so we want to
+    // run past that moment before each test.  Expect a call to hide warnings.
+    EXPECT_CALL(*observer(), OnNewSuggestions(_, _, _)).Times(1);
+    task_runner()->RunUntilIdle();
+    Mock::VerifyAndClearExpectations(observer());
+  }
+
+ private:
   DISALLOW_COPY_AND_ASSIGN(RecentTabSuggestionsProviderTest);
 };
 
 TEST_F(RecentTabSuggestionsProviderTest, ShouldConvertToSuggestions) {
-  auto recent_tabs_list = CreateDummyRecentTabs({1, 2});
   EXPECT_CALL(*observer(), OnNewSuggestions(_, _, _)).Times(2);
-  for (OfflinePageItem& recent_tab : recent_tabs_list)
-    AddOfflinePageToModel(recent_tab);
-
   EXPECT_CALL(
       *observer(),
       OnNewSuggestions(_, recent_tabs_category(),
@@ -131,7 +173,11 @@ TEST_F(RecentTabSuggestionsProviderTest, ShouldConvertToSuggestions) {
                                     GURL("http://dummy.com/2")),
                            Property(&ContentSuggestion::url,
                                     GURL("http://dummy.com/3")))));
-  AddOfflinePageToModel(CreateDummyRecentTab(3));
+
+  auto recent_tabs_list = CreateDummyRecentTabs({1, 2, 3});
+  for (OfflinePageItem& recent_tab : recent_tabs_list) {
+    AddTabAndOfflinePageToModel(recent_tab);
+  }
 }
 
 TEST_F(RecentTabSuggestionsProviderTest, ShouldSortByCreationTime) {
@@ -148,7 +194,7 @@ TEST_F(RecentTabSuggestionsProviderTest, ShouldSortByCreationTime) {
       OnNewSuggestions(_, recent_tabs_category(),
                        ElementsAre(Property(&ContentSuggestion::url,
                                             GURL("http://dummy.com/1")))));
-  AddOfflinePageToModel(CreateDummyRecentTab(1, now));
+  AddTabAndOfflinePageToModel(CreateDummyRecentTab(1, now));
 
   EXPECT_CALL(
       *observer(),
@@ -157,7 +203,7 @@ TEST_F(RecentTabSuggestionsProviderTest, ShouldSortByCreationTime) {
           ElementsAre(
               Property(&ContentSuggestion::url, GURL("http://dummy.com/1")),
               Property(&ContentSuggestion::url, GURL("http://dummy.com/2")))));
-  AddOfflinePageToModel(CreateDummyRecentTab(2, yesterday));
+  AddTabAndOfflinePageToModel(CreateDummyRecentTab(2, yesterday));
 
   offline_pages[1].last_access_time =
       offline_pages[0].last_access_time + base::TimeDelta::FromHours(1);
@@ -172,7 +218,7 @@ TEST_F(RecentTabSuggestionsProviderTest, ShouldSortByCreationTime) {
                                GURL("http://dummy.com/1")),
                       Property(&ContentSuggestion::url,
                                GURL("http://dummy.com/2")))));
-  AddOfflinePageToModel(CreateDummyRecentTab(3, tomorrow));
+  AddTabAndOfflinePageToModel(CreateDummyRecentTab(3, tomorrow));
 }
 
 TEST_F(RecentTabSuggestionsProviderTest, ShouldDeliverCorrectCategoryInfo) {
@@ -189,7 +235,7 @@ TEST_F(RecentTabSuggestionsProviderTest, ShouldDismiss) {
   EXPECT_CALL(*observer(), OnNewSuggestions(_, _, _)).Times(3);
   auto recent_tabs_list = CreateDummyRecentTabs({1, 2, 3});
   for (OfflinePageItem& recent_tab : recent_tabs_list) {
-    AddOfflinePageToModel(recent_tab);
+    AddTabAndOfflinePageToModel(recent_tab);
   }
 
   // Dismiss 2 and 3.
@@ -207,7 +253,7 @@ TEST_F(RecentTabSuggestionsProviderTest, ShouldDismiss) {
               Property(&ContentSuggestion::url, GURL("http://dummy.com/1")),
               Property(&ContentSuggestion::url, GURL("http://dummy.com/4")))));
 
-  AddOfflinePageToModel(CreateDummyRecentTab(4));
+  AddTabAndOfflinePageToModel(CreateDummyRecentTab(4));
   Mock::VerifyAndClearExpectations(observer());
 
   // And appear in the dismissed suggestions.
@@ -235,7 +281,7 @@ TEST_F(RecentTabSuggestionsProviderTest, ShouldDismiss) {
   // And appear in the reported suggestions for the category again.
   EXPECT_CALL(*observer(),
               OnNewSuggestions(_, recent_tabs_category(), SizeIs(5)));
-  AddOfflinePageToModel(CreateDummyRecentTab(5));
+  AddTabAndOfflinePageToModel(CreateDummyRecentTab(5));
   Mock::VerifyAndClearExpectations(observer());
 }
 
@@ -244,7 +290,7 @@ TEST_F(RecentTabSuggestionsProviderTest,
   EXPECT_CALL(*observer(), OnNewSuggestions(_, _, _)).Times(3);
   std::vector<OfflinePageItem> offline_pages = CreateDummyRecentTabs({1, 2, 3});
   for (OfflinePageItem& recent_tab : offline_pages)
-    AddOfflinePageToModel(recent_tab);
+    AddTabAndOfflinePageToModel(recent_tab);
 
   // Invalidation of suggestion 2 should be forwarded.
   EXPECT_CALL(*observer(), OnSuggestionInvalidated(_, GetDummySuggestionId(2)));
@@ -255,7 +301,7 @@ TEST_F(RecentTabSuggestionsProviderTest, ShouldClearDismissedOnInvalidate) {
   EXPECT_CALL(*observer(), OnNewSuggestions(_, _, _)).Times(3);
   std::vector<OfflinePageItem> offline_pages = CreateDummyRecentTabs({1, 2, 3});
   for (OfflinePageItem& recent_tab : offline_pages)
-    AddOfflinePageToModel(recent_tab);
+    AddTabAndOfflinePageToModel(recent_tab);
   EXPECT_THAT(ReadDismissedIDsFromPrefs(), IsEmpty());
 
   provider()->DismissSuggestion(GetDummySuggestionId(2));
@@ -269,7 +315,7 @@ TEST_F(RecentTabSuggestionsProviderTest, ShouldClearDismissedOnFetch) {
   EXPECT_CALL(*observer(), OnNewSuggestions(_, _, _)).Times(3);
   std::vector<OfflinePageItem> offline_pages = CreateDummyRecentTabs({1, 2, 3});
   for (OfflinePageItem& recent_tab : offline_pages)
-    AddOfflinePageToModel(recent_tab);
+    AddTabAndOfflinePageToModel(recent_tab);
 
   provider()->DismissSuggestion(GetDummySuggestionId(2));
   provider()->DismissSuggestion(GetDummySuggestionId(3));
@@ -294,8 +340,8 @@ TEST_F(RecentTabSuggestionsProviderTest, ShouldNotShowSameUrlMutlipleTimes) {
   // We leave IDs different, but make the URLs the same.
   offline_pages[2].url = offline_pages[0].url;
 
-  AddOfflinePageToModel(offline_pages[0]);
-  AddOfflinePageToModel(offline_pages[1]);
+  AddTabAndOfflinePageToModel(offline_pages[0]);
+  AddTabAndOfflinePageToModel(offline_pages[1]);
   Mock::VerifyAndClearExpectations(observer());
   EXPECT_CALL(*observer(),
               OnNewSuggestions(
@@ -304,13 +350,11 @@ TEST_F(RecentTabSuggestionsProviderTest, ShouldNotShowSameUrlMutlipleTimes) {
                       Property(&ContentSuggestion::publish_date, now),
                       Property(&ContentSuggestion::publish_date, tomorrow))));
 
-  AddOfflinePageToModel(offline_pages[2]);
+  AddTabAndOfflinePageToModel(offline_pages[2]);
 }
 
 TEST_F(RecentTabSuggestionsProviderTest,
        ShouldNotFetchIfAddedOfflinePageIsNotRecentTab) {
-  // The provider is not notified about the first recent tab yet.
-  model()->mutable_items()->push_back(CreateDummyRecentTab(1));
   // It should not fetch when not a recent tab is added, thus, it should not
   // report the first recent tab (which it is not aware about).
   EXPECT_CALL(*observer(), OnNewSuggestions(_, _, _)).Times(0);
@@ -318,12 +362,45 @@ TEST_F(RecentTabSuggestionsProviderTest,
       2, offline_pages::kDefaultNamespace));
 }
 
+TEST_F(RecentTabSuggestionsProviderTestNoLoad, ShouldFetchOnLoad) {

[vitaliii, 2017/02/16 08:11:04]

Could you please add a comment saying that this test class does not have SetUp
(and to bring attention that this is actually a different test class from other
tests)?

At first, I missed that there are 2 test classes and was confused how this
worked at all.

[dewittj, 2017/02/17 22:33:38]

Done. Also moved to the bottom to separate the two types of test fixtures.

+  // We should only fetch once, when the adapter is loaded.

[vitaliii, 2017/02/16 08:11:04]

s/ We should/ On startup we should

[dewittj, 2017/02/17 22:33:38]

Reworded.

+  EXPECT_CALL(
+      *observer(),
+      OnNewSuggestions(
+          _, recent_tabs_category(),
+          UnorderedElementsAre(
+              Property(&ContentSuggestion::url, GURL("http://dummy.com/1")),
+              Property(&ContentSuggestion::url, GURL("http://dummy.com/2")))));
+
+  AddTabAndOfflinePageToModel(CreateDummyRecentTab(1));

[vitaliii, 2017/02/16 08:11:04]

Could you please add recent tabs before EXPECT_CALL?

[dewittj, 2017/02/17 22:33:38]

In this top location, it catches improper |OnNewSuggestions| calls made before
load.  So I prefer the EXPECT at the top.

+  AddTabAndOfflinePageToModel(CreateDummyRecentTab(2));
+  // The provider is not notified about the recent tabs yet.
+  task_runner()->RunUntilIdle();
+  // However, it must return both tabs when the model is loaded.
+}
+
 TEST_F(RecentTabSuggestionsProviderTest,
-       ShouldFetchIfAddedOfflinePageIsRecentTab) {
-  // The provider is not notified about the first recent tab yet.
-  model()->mutable_items()->push_back(CreateDummyRecentTab(1));
-  // However, it must return the first recent tab (i.e. manually fetch it) even
-  // when notified about a different recent tab.
+       ShouldInvalidateSuggestionWhenTabGone) {
+  OfflinePageItem first_tab = CreateDummyRecentTab(1);
+  AddTabAndOfflinePageToModel(first_tab);
+  Mock::VerifyAndClearExpectations(observer());
+
+  EXPECT_CALL(*observer(), OnSuggestionInvalidated(_, GetDummySuggestionId(1)))
+      .Times(1);
+  RemoveTab(offline_pages::RecentTabsUIAdapterDelegate::TabIdFromClientId(
+      first_tab.client_id));
+  // Removing an unknown tab should not cause extra invalidations.
+  RemoveTab(42);
+}
+
+TEST_F(RecentTabSuggestionsProviderTest, ShouldNotShowPagesWithoutTab) {
+  EXPECT_CALL(*observer(), OnNewSuggestions(_, _, _)).Times(0);
+  // The provider is not notified about the first recent tab yet (no tab).
+  OfflinePageItem first_tab = CreateDummyRecentTab(1);
+  AddOfflinePageToModel(first_tab);
+
+  Mock::VerifyAndClearExpectations(observer());
+  EXPECT_CALL(*observer(), OnNewSuggestions(_, _, _)).Times(1);
   EXPECT_CALL(
       *observer(),
       OnNewSuggestions(
@@ -331,7 +408,30 @@ TEST_F(RecentTabSuggestionsProviderTest,
           UnorderedElementsAre(
               Property(&ContentSuggestion::url, GURL("http://dummy.com/1")),
               Property(&ContentSuggestion::url, GURL("http://dummy.com/2")))));
-  AddOfflinePageToModel(CreateDummyRecentTab(2));
+
+  AddTab(offline_pages::RecentTabsUIAdapterDelegate::TabIdFromClientId(
+      first_tab.client_id));
+  OfflinePageItem second_tab = CreateDummyRecentTab(2);
+  AddTabAndOfflinePageToModel(second_tab);
+
+  Mock::VerifyAndClearExpectations(observer());
+
+  EXPECT_CALL(*observer(), OnNewSuggestions(_, _, _)).Times(0);
+  // |RemoveTab| by itself doesn't cause OnNewSuggestions to be called.
+  RemoveTab(offline_pages::RecentTabsUIAdapterDelegate::TabIdFromClientId(
+      second_tab.client_id));
+  Mock::VerifyAndClearExpectations(observer());
+
+  // But when we get another tab, OnNewSuggestions will be called.
+  EXPECT_CALL(
+      *observer(),
+      OnNewSuggestions(
+          _, recent_tabs_category(),
+          UnorderedElementsAre(
+              Property(&ContentSuggestion::url, GURL("http://dummy.com/1")),
+              Property(&ContentSuggestion::url, GURL("http://dummy.com/3")))));
+
+  AddTabAndOfflinePageToModel(CreateDummyRecentTab(3));
 }
 
 }  // namespace ntp_snippets