[NTP::SectionOrder] Replace CategoryFactory with a category ranker.

components/ntp_snippets/category_rankers/constant_category_ranker_unittest.cc

Index: components/ntp_snippets/category_rankers/constant_category_ranker_unittest.cc
diff --git a/components/ntp_snippets/category_rankers/constant_category_ranker_unittest.cc b/components/ntp_snippets/category_rankers/constant_category_ranker_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e0286d49715dc88b98dc417b50ba20123b9b195d
--- /dev/null
+++ b/components/ntp_snippets/category_rankers/constant_category_ranker_unittest.cc
@@ -0,0 +1,124 @@
+// 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/constant_category_ranker.h"
+
+#include "components/ntp_snippets/category.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace ntp_snippets {
+
+class ConstantCategoryRankerTest : public testing::Test {
+ public:
+  ConstantCategoryRankerTest()
+      : unused_remote_category_id_(
+            static_cast<int>(KnownCategories::LAST_KNOWN_REMOTE_CATEGORY) + 1) {
+  }
+
+  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();
+    }
+  }
+
+  ConstantCategoryRanker* ranker() { return &ranker_; }
+
+ private:
+  ConstantCategoryRanker ranker_;
+  int unused_remote_category_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(ConstantCategoryRankerTest);
+};
+
+TEST_F(ConstantCategoryRankerTest, 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(ConstantCategoryRankerTest, 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(ConstantCategoryRankerTest, 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(ConstantCategoryRankerTest,
+       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(ConstantCategoryRankerTest,
+       AddingSameCategoryTwiceShouldNotChangeOrder) {
+  Category first = AddUnusedRemoteCategory();
+  Category second = AddUnusedRemoteCategory();
+
+  ASSERT_TRUE(CompareCategories(first, second));
+  ASSERT_FALSE(CompareCategories(second, first));
+
+  ranker()->AppendCategoryIfNecessary(first);
+
+  EXPECT_TRUE(CompareCategories(first, second));
+  EXPECT_FALSE(CompareCategories(second, first));
+}
+
+TEST_F(ConstantCategoryRankerTest, ShouldSortNonConsequtiveRemoteCategories) {
+  AddUnusedRemoteCategories(3);
+
+  Category first = AddUnusedRemoteCategory();
+
+  AddUnusedRemoteCategories(3);
+
+  Category second = AddUnusedRemoteCategory();
+
+  AddUnusedRemoteCategories(3);
+
+  EXPECT_TRUE(CompareCategories(first, second));
+  EXPECT_FALSE(CompareCategories(second, first));
+}
+
+}  // namespace ntp_snippets