[NTP::SectionOrder] Make dismissed category penalty a variation param.

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
index 1956feac0b86c70d93951cd44bf86ecc2ba3fdc5..7c1901316ec776ac2ce82d5c150d3442c19b5a02 100644
--- a/components/ntp_snippets/category_rankers/click_based_category_ranker_unittest.cc
+++ b/components/ntp_snippets/category_rankers/click_based_category_ranker_unittest.cc
@@ -5,12 +5,16 @@
 #include "components/ntp_snippets/category_rankers/click_based_category_ranker.h"
 
 #include "base/memory/ptr_util.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/test/simple_test_clock.h"
 #include "base/time/default_clock.h"
 #include "base/time/time.h"
 #include "components/ntp_snippets/category.h"
 #include "components/ntp_snippets/category_rankers/constant_category_ranker.h"
+#include "components/ntp_snippets/features.h"
+#include "components/ntp_snippets/ntp_snippets_constants.h"
 #include "components/prefs/testing_pref_service.h"
+#include "components/variations/variations_params_manager.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -65,12 +69,21 @@ class ClickBasedCategoryRankerTest : public testing::Test {
     ranker()->OnCategoryDismissed(category);
   }
 
+  void SetDismissedCategoryPenaltyVariationParam(int value) {
+    variation_params_manager_.SetVariationParamsWithFeatureAssociations(
+        ntp_snippets::kStudyName,
+        {{"click_based_category_ranker-dismissed_category_penalty",
+          base::IntToString(value)}},
+        {kCategoryRanker.name});
+  }
+
   ClickBasedCategoryRanker* ranker() { return ranker_.get(); }
 
  private:
   std::unique_ptr<TestingPrefServiceSimple> pref_service_;
   int unused_remote_category_id_;
   std::unique_ptr<ClickBasedCategoryRanker> ranker_;
+  variations::testing::VariationParamsManager variation_params_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(ClickBasedCategoryRankerTest);
 };
@@ -324,6 +337,8 @@ TEST_F(ClickBasedCategoryRankerTest, ShouldPersistLastDecayTimeWhenRestarted) {
 }
 
 TEST_F(ClickBasedCategoryRankerTest, ShouldMoveCategoryDownWhenDismissed) {
+  SetDismissedCategoryPenaltyVariationParam(2);
+
   // Take top categories.
   std::vector<KnownCategories> default_order =
       ConstantCategoryRanker::GetKnownCategoriesDefaultOrder();
@@ -337,6 +352,8 @@ TEST_F(ClickBasedCategoryRankerTest, ShouldMoveCategoryDownWhenDismissed) {
 
 TEST_F(ClickBasedCategoryRankerTest,
        ShouldMoveSecondToLastCategoryDownWhenDismissed) {
+  SetDismissedCategoryPenaltyVariationParam(2);
+
   // Add categories to the bottom.
   Category first = AddUnusedRemoteCategory();
   Category second = AddUnusedRemoteCategory();
@@ -348,6 +365,8 @@ TEST_F(ClickBasedCategoryRankerTest,
 
 TEST_F(ClickBasedCategoryRankerTest,
        ShouldNotMoveCategoryTooMuchDownWhenDismissed) {
+  SetDismissedCategoryPenaltyVariationParam(2);
+
   // Add enough categories to the end.
   std::vector<Category> categories;
   const int penalty = ClickBasedCategoryRanker::GetDismissedCategoryPenalty();
@@ -377,6 +396,8 @@ TEST_F(ClickBasedCategoryRankerTest,
 
 TEST_F(ClickBasedCategoryRankerTest,
        ShouldNotChangeOrderOfOtherCategoriesWhenDismissed) {
+  SetDismissedCategoryPenaltyVariationParam(2);
+
   // Add enough categories to the end.
   std::vector<Category> categories;
   const int penalty = ClickBasedCategoryRanker::GetDismissedCategoryPenalty();
@@ -399,6 +420,8 @@ TEST_F(ClickBasedCategoryRankerTest,
 }
 
 TEST_F(ClickBasedCategoryRankerTest, ShouldNotMoveLastCategoryWhenDismissed) {
+  SetDismissedCategoryPenaltyVariationParam(2);
+
   Category first = AddUnusedRemoteCategory();
   Category second = AddUnusedRemoteCategory();
 
@@ -409,6 +432,8 @@ TEST_F(ClickBasedCategoryRankerTest, ShouldNotMoveLastCategoryWhenDismissed) {
 
 TEST_F(ClickBasedCategoryRankerTest,
        ShouldReduceLastCategoryClicksWhenDismissed) {
+  SetDismissedCategoryPenaltyVariationParam(2);
+
   Category first = AddUnusedRemoteCategory();
   Category second = AddUnusedRemoteCategory();
 
@@ -432,6 +457,46 @@ TEST_F(ClickBasedCategoryRankerTest,
   EXPECT_FALSE(CompareCategories(first, second));
 }
 
+TEST_F(ClickBasedCategoryRankerTest,
+       ShouldTakeVariationValueForDismissedCategoryPenalty) {
+  const int penalty = 10203;
+  SetDismissedCategoryPenaltyVariationParam(penalty);
+  EXPECT_EQ(penalty, ClickBasedCategoryRanker::GetDismissedCategoryPenalty());
+}
+
+TEST_F(ClickBasedCategoryRankerTest,
+       ShouldDoNothingWhenCategoryDismissedIfPenaltyIsZero) {
+  SetDismissedCategoryPenaltyVariationParam(0);
+
+  // 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();
+  Category third = AddUnusedRemoteCategory();
+
+  NotifyOnSuggestionOpened(
+      /*times=*/1, second);
+
+  // This should be ignored, because the penalty is set to 0.
+  NotifyOnCategoryDismissed(second);
+
+  // The second category should stay where it was.
+  EXPECT_TRUE(CompareCategories(first, second));
+  EXPECT_TRUE(CompareCategories(second, third));
+
+  // Try to move the second category up assuming that the previous click is
+  // still there.
+  NotifyOnSuggestionOpened(
+      /*times=*/ClickBasedCategoryRanker::GetPassingMargin() - 1, second);
+
+  // It should overtake the first category, because the dismissal should be
+  // ignored and the click should remain.
+  EXPECT_FALSE(CompareCategories(first, second));
+}
+
 TEST_F(ClickBasedCategoryRankerTest, ShouldRestoreDefaultOrderOnClearHistory) {
   std::vector<KnownCategories> default_order =
       ConstantCategoryRanker::GetKnownCategoriesDefaultOrder();