[NTP::SectionOrder] First version of click based category ranker.

components/ntp_snippets/category_rankers/click_based_category_ranker_unittest.cc

Index: components/ntp_snippets/category_rankers/click_based_category_ranker_unittest.cc
diff --git a/components/ntp_snippets/category_rankers/click_based_category_ranker_unittest.cc b/components/ntp_snippets/category_rankers/click_based_category_ranker_unittest.cc
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+++ b/components/ntp_snippets/category_rankers/click_based_category_ranker_unittest.cc
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+// 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/category_rankers/click_based_category_ranker.h"
+
+#include "base/memory/ptr_util.h"
+#include "components/ntp_snippets/category.h"
+#include "components/ntp_snippets/category_rankers/constant_category_ranker.h"
+#include "components/prefs/testing_pref_service.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace ntp_snippets {
+
+class ClickBasedCategoryRankerTest : public testing::Test {
+ public:
+  ClickBasedCategoryRankerTest()
+      : pref_service_(base::MakeUnique<TestingPrefServiceSimple>()),
+        unused_remote_category_id_(
+            static_cast<int>(KnownCategories::LAST_KNOWN_REMOTE_CATEGORY) + 1) {
+    ClickBasedCategoryRanker::RegisterProfilePrefs(pref_service_->registry());
+
+    ranker_ = base::MakeUnique<ClickBasedCategoryRanker>(pref_service_.get());
+  }
+
+  int GetUnusedRemoteCategoryID() { return unused_remote_category_id_++; }
+
+  Category GetUnusedRemoteCategory() {
+    return Category::FromIDValue(GetUnusedRemoteCategoryID());
+  }
+
+  bool CompareCategories(const Category& left, const Category& right) {
+    return ranker()->Compare(left, right);
+  }
+
+  Category AddUnusedRemoteCategory() {
+    Category category = GetUnusedRemoteCategory();
+    ranker()->AppendCategoryIfNecessary(category);
+    return category;
+  }
+
+  void AddUnusedRemoteCategories(int quantity) {
+    for (int i = 0; i < quantity; ++i) {
+      AddUnusedRemoteCategory();
+    }
+  }
+
+  void ResetRanker() {
+    ranker_ = base::MakeUnique<ClickBasedCategoryRanker>(pref_service_.get());
+  }
+
+  void NotifyOnSuggestionOpened(int times, Category category) {
+    for (int i = 0; i < times; ++i) {
+      ranker()->OnSuggestionOpened(category);
+    }
+  }
+
+  ClickBasedCategoryRanker* ranker() { return ranker_.get(); }
+
+ private:
+  std::unique_ptr<TestingPrefServiceSimple> pref_service_;
+  int unused_remote_category_id_;
+  std::unique_ptr<ClickBasedCategoryRanker> ranker_;
+
+  DISALLOW_COPY_AND_ASSIGN(ClickBasedCategoryRankerTest);
+};
+
+TEST_F(ClickBasedCategoryRankerTest, ShouldSortRemoteCategoriesByWhenAdded) {
+  const Category first = GetUnusedRemoteCategory();
+  const Category second = GetUnusedRemoteCategory();
+  // Categories are added in decreasing id order to test that they are not
+  // compared by id.
+  ranker()->AppendCategoryIfNecessary(second);
+  ranker()->AppendCategoryIfNecessary(first);
+  EXPECT_TRUE(CompareCategories(second, first));
+  EXPECT_FALSE(CompareCategories(first, second));
+}
+
+TEST_F(ClickBasedCategoryRankerTest, ShouldSortLocalCategoriesBeforeRemote) {
+  const Category remote_category = AddUnusedRemoteCategory();
+  const Category local_category =
+      Category::FromKnownCategory(KnownCategories::BOOKMARKS);
+  EXPECT_TRUE(CompareCategories(local_category, remote_category));
+  EXPECT_FALSE(CompareCategories(remote_category, local_category));
+}
+
+TEST_F(ClickBasedCategoryRankerTest,
+       CompareShouldReturnFalseForSameCategories) {
+  const Category remote_category = AddUnusedRemoteCategory();
+  EXPECT_FALSE(CompareCategories(remote_category, remote_category));
+
+  const Category local_category =
+      Category::FromKnownCategory(KnownCategories::BOOKMARKS);
+  EXPECT_FALSE(CompareCategories(local_category, local_category));
+}
+
+TEST_F(ClickBasedCategoryRankerTest,
+       AddingMoreRemoteCategoriesShouldNotChangePreviousOrder) {
+  AddUnusedRemoteCategories(3);
+
+  Category first = AddUnusedRemoteCategory();
+  Category second = AddUnusedRemoteCategory();
+
+  ASSERT_TRUE(CompareCategories(first, second));
+  ASSERT_FALSE(CompareCategories(second, first));
+
+  AddUnusedRemoteCategories(3);
+
+  EXPECT_TRUE(CompareCategories(first, second));
+  EXPECT_FALSE(CompareCategories(second, first));
+}
+
+TEST_F(ClickBasedCategoryRankerTest, ShouldChangeOrderOfNonTopCategories) {
+  // Add dummy remote categories to ensure that the following categories are not
+  // in the top anymore.
+  AddUnusedRemoteCategories(
+      ClickBasedCategoryRanker::GetNumTopCategoriesWithExtraMargin());
+
+  Category first = AddUnusedRemoteCategory();
+  Category second = AddUnusedRemoteCategory();
+
+  ASSERT_TRUE(CompareCategories(first, second));
+  ASSERT_FALSE(CompareCategories(second, first));
+
+  NotifyOnSuggestionOpened(
+      /*times=*/ClickBasedCategoryRanker::GetPassingMargin(), second);
+
+  EXPECT_TRUE(CompareCategories(second, first));
+  EXPECT_FALSE(CompareCategories(first, second));
+}
+
+TEST_F(ClickBasedCategoryRankerTest,
+       ShouldNotChangeOrderRightAfterOrderChange) {
+  // Add dummy remote categories to ensure that the following categories are not
+  // in the top anymore.
+  AddUnusedRemoteCategories(
+      ClickBasedCategoryRanker::GetNumTopCategoriesWithExtraMargin());
+
+  // Two non-top categories are added.
+  Category first = AddUnusedRemoteCategory();
+  Category second = AddUnusedRemoteCategory();
+  ASSERT_TRUE(CompareCategories(first, second));
+  ASSERT_FALSE(CompareCategories(second, first));
+  // Their order is changed.
+  NotifyOnSuggestionOpened(
+      /*times=*/ClickBasedCategoryRanker::GetPassingMargin(), second);
+  ASSERT_TRUE(CompareCategories(second, first));
+  ASSERT_FALSE(CompareCategories(first, second));
+
+  // Click on the lower category.
+  NotifyOnSuggestionOpened(/*times=*/1, first);
+
+  // Order should not change.
+  EXPECT_TRUE(CompareCategories(second, first));
+  EXPECT_FALSE(CompareCategories(first, second));
+}
+
+TEST_F(ClickBasedCategoryRankerTest,
+       ShouldNotMoveCategoryMoreThanOncePerClick) {
+  // Add dummy remote categories to ensure that the following categories are not
+  // in the top anymore.
+  AddUnusedRemoteCategories(
+      ClickBasedCategoryRanker::GetNumTopCategoriesWithExtraMargin());
+
+  // Non-top categories are added.
+  Category first = AddUnusedRemoteCategory();
+  Category second = AddUnusedRemoteCategory();
+  Category third = AddUnusedRemoteCategory();
+
+  // Move the third category up.
+  NotifyOnSuggestionOpened(
+      /*times=*/ClickBasedCategoryRanker::GetPassingMargin(), third);
+  EXPECT_TRUE(CompareCategories(third, second));
+  // But only on one position even though the first category has low counts.
+  EXPECT_TRUE(CompareCategories(first, third));
+  // However, another click must move it further.
+  NotifyOnSuggestionOpened(/*times=*/1, third);
+  EXPECT_TRUE(CompareCategories(third, first));
+}
+
+TEST_F(ClickBasedCategoryRankerTest,
+       ShouldNotMoveTopCategoryRightAfterThreshold) {
+  ASSERT_GE(ClickBasedCategoryRanker::GetNumTopCategoriesWithExtraMargin(), 1);
+
+  // At least one top category is added from the default order.
+  std::vector<KnownCategories> default_order =
+      ConstantCategoryRanker::GetKnownCategoriesDefaultOrder();
+  Category first = Category::FromKnownCategory(default_order[0]);
+  Category second = Category::FromKnownCategory(default_order[1]);
+
+  // Try to move the second category up as if the first category was non-top.
+  NotifyOnSuggestionOpened(
+      /*times=*/ClickBasedCategoryRanker::GetPassingMargin(), second);
+
+  // Nothing should change, because the first category is top.
+  EXPECT_TRUE(CompareCategories(first, second));
+}
+
+TEST_F(ClickBasedCategoryRankerTest, ShouldPersistOrderAndClicksWhenRestarted) {
+  // Add dummy remote categories to ensure that the following categories are not
+  // in the top anymore.
+  AddUnusedRemoteCategories(
+      ClickBasedCategoryRanker::GetNumTopCategoriesWithExtraMargin());
+
+  // Non-top categories are added.
+  Category first = AddUnusedRemoteCategory();
+  Category second = AddUnusedRemoteCategory();
+  Category third = AddUnusedRemoteCategory();
+
+  // Change the order.
+  NotifyOnSuggestionOpened(
+      /*times=*/ClickBasedCategoryRanker::GetPassingMargin(), third);
+  ASSERT_TRUE(CompareCategories(third, second));
+  ASSERT_TRUE(CompareCategories(first, third));
+
+  // Simulate Chrome restart.
+  ResetRanker();
+
+  // The old order must be preserved.
+  EXPECT_TRUE(CompareCategories(third, second));
+
+  // Clicks must be preserved as well.
+  NotifyOnSuggestionOpened(
+      /*times=*/1, third);
+  EXPECT_TRUE(CompareCategories(third, first));
+}
+
+}  // namespace ntp_snippets