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

components/ntp_snippets/category_unittest.cc

+// 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.h"
+
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace ntp_snippets {
+
+TEST(CategoryTest, FromKnownCategoryShouldReturnSameCategoryForSameInput) {
+  const KnownCategories known_category = KnownCategories::BOOKMARKS;
+  Category first = Category::FromKnownCategory(known_category);
+  Category second = Category::FromKnownCategory(known_category);
+  EXPECT_EQ(first, second);
+}
+
+TEST(CategoryFactoryTest,
+     FromRemoteCategoryShouldReturnSameCategoryForSameInput) {
+  const int remote_category_id = 123;
+  Category first = Category::FromRemoteCategory(remote_category_id);
+  Category second = Category::FromRemoteCategory(remote_category_id);
+  EXPECT_EQ(first, second);
+}
+
+TEST(CategoryFactoryTest, FromIDValueShouldReturnSameKnownCategory) {
+  Category known_category =
+      Category::FromKnownCategory(KnownCategories::BOOKMARKS);
+  Category known_category_by_id = Category::FromIDValue(known_category.id());
+  EXPECT_EQ(known_category, known_category_by_id);
+}
+
+TEST(CategoryFactoryTest, FromIDValueShouldReturnSameRemoteCategory) {
+  const int remote_category_id = 123;
+  Category remote_category = Category::FromRemoteCategory(remote_category_id);
+  Category remote_category_by_id = Category::FromIDValue(remote_category.id());
+  EXPECT_EQ(remote_category, remote_category_by_id);
+}
+
+}  // namespace ntp_snippets