Simplify control data code, and add tests

For variants A and B, all browse pages will contain popular links.
For variants C and Z ie the control state, only business and benefits will
contain popular links. The other 14 will default to hiding popular tasks
entirely - as this is the default behaviour currently live on GOV.UK

This commit adds specs to highlight this, and simplifies the existing code. There
is no behavioural change.

app/helpers/browse_helper.rb

@@ -1,50 +1,32 @@
 module BrowseHelper
-  def variant_a_popular_links?(slug)
-    I18n.exists?("#{slug}.variant_a", scope: "browse.popular_links")
-  end
-
-  def variant_a_popular_links(slug)
-    I18n.t("#{slug}.variant_a", scope: "browse.popular_links")
-  end
-
-  def variant_b_popular_links?(slug)
-    I18n.exists?("#{slug}.variant_b", scope: "browse.popular_links")
-  end
-
-  def variant_b_popular_links(slug)
-    I18n.t("#{slug}.variant_b", scope: "browse.popular_links")
+  def display_popular_links_for_slug?(slug)
+    popular_links_data(slug).present?
   end
 
-  def control_popular_links?(slug)
+  def control_key_is_present?(slug)
     I18n.exists?("#{slug}.control", scope: "browse.popular_links")
   end
 
-  def control_popular_links(slug)
-    I18n.t("#{slug}.control", scope: "browse.popular_links")
-  end
-
-  def display_popular_links_for_slug?(slug)
-    if popular_tasks_variant_a_page?
-      variant_a_popular_links?(slug)
-    elsif popular_tasks_variant_b_page?
-      variant_b_popular_links?(slug)
+  def control_data(slug)
+    if control_key_is_present?(slug)
+      I18n.t("browse.popular_links.#{slug}.control")
     else
-      control_popular_links?(slug)
+      []
     end
   end
 
-  def variant_popular_links_for_slug(slug)
+  def popular_links_data(slug)
     if popular_tasks_variant_a_page?
-      variant_a_popular_links(slug)
+      I18n.t("browse.popular_links.#{slug}.variant_a")
     elsif popular_tasks_variant_b_page?
-      variant_b_popular_links(slug)
+      I18n.t("browse.popular_links.#{slug}.variant_b")
     else
-      control_popular_links(slug)
+      control_data(slug)
     end
   end
 
   def popular_links_for_slug(slug)
-    links = variant_popular_links_for_slug(slug)
+    links = popular_links_data(slug)
     count = links.length
     links.map.with_index(1) do |link, index|
       {

spec/features/mainstream_browsing_spec.rb

@@ -42,6 +42,74 @@
       end
     end
 
+    context "Control variants" do
+      scenario "when visiting business and benefits i.e. pages that originally had popular tasks" do
+        with_variant PopularTasks: "C" do
+          content_item["base_path"] = "/browse/business"
+          stub_content_store_has_item("/browse/business", content_item)
+          visit "/browse/business"
+          expect(page).to have_content("Popular tasks")
+
+          links = I18n.t("browse.popular_links.business.control")
+          links.each do |link|
+            expect(page).to have_link(link["title"])
+          end
+
+          content_item["base_path"] = "/browse/benefits"
+          stub_content_store_has_item("/browse/benefits", content_item)
+          visit "/browse/benefits"
+          expect(page).to have_content("Popular tasks")
+
+          links = I18n.t("browse.popular_links.benefits.control")
+          links.each do |link|
+            expect(page).to have_link(link["title"])
+          end
+        end
+
+        with_variant PopularTasks: "Z" do
+          content_item["base_path"] = "/browse/business"
+          stub_content_store_has_item("/browse/business", content_item)
+          visit "/browse/business"
+          expect(page).to have_content("Popular tasks")
+
+          links = I18n.t("browse.popular_links.business.control")
+          links.each do |link|
+            expect(page).to have_link(link["title"])
+          end
+
+          content_item["base_path"] = "/browse/benefits"
+          stub_content_store_has_item("/browse/benefits", content_item)
+          visit "/browse/benefits"
+          expect(page).to have_content("Popular tasks")
+
+          links = I18n.t("browse.popular_links.benefits.control")
+          links.each do |link|
+            expect(page).to have_link(link["title"])
+          end
+        end
+      end
+
+      scenario "when visiting pages that originally had no popular tasks" do
+        slugs_with_no_popular_tasks_originally = browse_slugs - %i[benefits business]
+
+        slugs_with_no_popular_tasks_originally.each do |browse_slug|
+          browse_path = "/browse/#{browse_slug}"
+          content_item["base_path"] = browse_path
+          stub_content_store_has_item(browse_path, content_item)
+
+          with_variant PopularTasks: "C" do
+            visit browse_path
+            expect(page).not_to have_content("Popular tasks")
+          end
+
+          with_variant PopularTasks: "Z" do
+            visit browse_path
+            expect(page).not_to have_content("Popular tasks")
+          end
+        end
+      end
+    end
+
     browse_slugs.each do |browse_slug|
       browse_path = "/browse/#{browse_slug}"