Adding page view goal for experiments (#17696)

With comments, publishing articles, and reactions we had symmetry on two
goals:

- Create a _subject_ (e.g. Comment, Published Article, Reaction)
- Create four _subjects_ within a week.

For page views we only had "Create four _subjects_ within a week."  This
PR addes the "Create a _subject_".

To do this required adjusting some tests as they were too specific in
nature (looking at an expected count).

In addition, in consultation with Jennie, I've updated the experiment
order to better reflect some hierarchical importance.

**Rollback considerations:**

This also includes a feature flag that we can explicitly disable if we
overload the application with workers handling reaction goals.  Using
`FeatureFlag.accessible?(:field_test_event_single_create_pageview)`
returns `true` unless we explicitly disable this flag.

Related to forem/forem#17673
Related to forem/forem#17669
Closes forem/forem#17691

app/models/ab_experiment/goal_conversion_handler.rb

@@ -58,6 +58,11 @@ class AbExperiment
     end
 
     def convert_pageview_goal(experiment:, experiment_start_date:)
+      # TODO: Remove once we know that this test is not over-heating the application.  That would be a
+      # few days after the deploy to DEV of this change.
+      if FeatureFlag.accessible?(:field_test_event_single_create_pageview)
+        field_test_converted(experiment, participant: user, goal: goal) # base is someone viewed a page
+      end
       pageview_goal(experiment,
                     [7.days.ago, experiment_start_date].max,
                     "DATE(created_at)",

config/field_test.yml

@@ -12,18 +12,20 @@ experiments:
       - 80
       - 20
     goals:
+      - user_creates_pageview
+      - user_creates_article_reaction
       - user_creates_comment
-      - user_creates_comment_on_at_least_four_different_days_within_a_week
-      - user_views_pages_on_at_least_four_different_days_within_a_week
-      - user_views_pages_on_at_least_four_different_hours_within_a_day
-      - user_views_pages_on_at_least_nine_different_days_within_two_weeks
-      - user_views_pages_on_at_least_twelve_different_hours_within_five_days
       - user_publishes_post
+      - user_views_pages_on_at_least_four_different_days_within_a_week
+      - user_creates_article_reaction_on_four_different_days_within_a_week
+      - user_creates_comment_on_at_least_four_different_days_within_a_week
+      - user_publishes_post_on_four_different_days_within_a_week
+      # These are historical and may be userful
+      - user_views_pages_on_at_least_four_different_hours_within_a_day
+      - user_views_pages_on_at_least_twelve_different_hours_within_five_days
+      - user_views_pages_on_at_least_nine_different_days_within_two_weeks
       - user_publishes_post_at_least_two_times_within_week
       - user_publishes_post_at_least_two_times_within_two_weeks
-      - user_publishes_post_on_four_different_days_within_a_week
-      - user_creates_article_reaction
-      - user_creates_article_reaction_on_four_different_days_within_a_week
 exclude:
   bots: true
 

spec/models/ab_experiment/goal_conversion_handler_spec.rb

@@ -125,6 +125,14 @@ RSpec.describe AbExperiment::GoalConversionHandler do
         field_test(AbExperiment::CURRENT_FEED_STRATEGY_EXPERIMENT, participant: user)
       end
 
+      it "records a field test when user views a page", :aggregate_failures do
+        create(:page_view, user_id: user.id)
+        handler.call
+        expect(FieldTest::Event.last.field_test_membership.participant_id).to eq(user.id.to_s)
+        expect(FieldTest::Event.pluck(:name))
+          .to include(goal)
+      end
+
       it "records user_views_pages_on_at_least_four_different_days_within_a_week field test conversion",
          :aggregate_failures do
         7.times do |n|
@@ -164,7 +172,8 @@ RSpec.describe AbExperiment::GoalConversionHandler do
           create(:page_view, user_id: user.id, created_at: n.days.ago)
         end
         handler.call
-        expect(FieldTest::Event.all.size).to be(0)
+        expect(FieldTest::Event.pluck(:name))
+          .not_to include("user_views_pages_on_at_least_twelve_different_hours_within_five_days")
       end
 
       it "records user_views_pages_on_at_least_four_different_hours_within_a_day field test conversionn",
@@ -175,7 +184,7 @@ RSpec.describe AbExperiment::GoalConversionHandler do
         handler.call
         expect(FieldTest::Event.last.field_test_membership.participant_id).to eq(user.id.to_s)
         expect(FieldTest::Event.pluck(:name))
-          .to include("user_views_pages_on_at_least_four_different_hours_within_a_day")
+          .to eq([goal, "user_views_pages_on_at_least_four_different_hours_within_a_day"])
       end
 
       it "does not record user_views_article_four_hours_in_day field test conversion for non-qualifying activity" do
@@ -183,7 +192,8 @@ RSpec.describe AbExperiment::GoalConversionHandler do
           create(:page_view, user_id: user.id, created_at: n.hours.ago)
         end
         handler.call
-        expect(FieldTest::Event.all.size).to be(0)
+        expect(FieldTest::Event.pluck(:name))
+          .not_to include("user_views_pages_on_at_least_four_different_hours_within_a_day")
       end
     end