Merge pull request #3609 from alphagov/browse_ab_test

Set up AB test logic for NewBrowse

app/controllers/application_controller.rb

@@ -1,8 +1,10 @@
 class ApplicationController < ActionController::Base
   include Slimmer::Template
+  include NewBrowseAbTestable
 
-  helper_method :level_two_browse_variant
+  helper_method :new_browse_variant
   helper_method :content_item_h
+  helper_method :new_browse_page_under_test?
 
   protect_from_forgery with: :exception
 

app/controllers/browse_controller.rb

@@ -10,6 +10,8 @@ def index
   end
 
   def show
+    set_new_browse_response_header if new_browse_page_under_test?
+
     page = MainstreamBrowsePage.find("/browse/#{params[:top_level_slug]}")
     setup_content_item_and_navigation_helpers(page)
 

app/controllers/new_browse_ab_testable.rb

@@ -0,0 +1,31 @@
+module NewBrowseAbTestable
+  # placeholder custom dimension
+  CUSTOM_DIMENSION = 67
+
+  ALLOWED_VARIANTS = %w[A B Z].freeze
+
+  def new_browse_test
+    @new_browse_test ||= GovukAbTesting::AbTest.new(
+      "NewBrowse",
+      dimension: CUSTOM_DIMENSION,
+      allowed_variants: ALLOWED_VARIANTS,
+      control_variant: "Z",
+    )
+  end
+
+  def new_browse_variant
+    new_browse_test.requested_variant(request.headers)
+  end
+
+  def set_new_browse_response_header
+    new_browse_variant.configure_response(response)
+  end
+
+  def new_browse_variant_b?
+    page_under_test? && new_browse_variant.variant?("B")
+  end
+
+  def new_browse_page_under_test?
+    request.path.starts_with?("/browse")
+  end
+end

app/views/layouts/application.html.erb

@@ -39,6 +39,7 @@
   <%= javascript_include_tag "application" %>
   <%= csrf_meta_tags %>
   <%= yield :meta_tags %>
+  <%= new_browse_variant.analytics_meta_tag.html_safe if new_browse_page_under_test? %>
   <%= render 'govuk_publishing_components/components/meta_tags', content_item: content_item_h %>
   <%=
     render_component_stylesheets

spec/controllers/browse_controller_spec.rb

@@ -16,6 +16,10 @@
 
       expect(response.headers["Cache-Control"]).to eq("max-age=300, public")
     end
+
+    it "is not included in the newbrowse AB test" do
+      assert_response_not_modified_for_ab_test("NewBrowse")
+    end
   end
 
   describe "GET top_level_browse_page" do
@@ -42,6 +46,18 @@
         expect(response.content_type).to eq "text/html; charset=utf-8"
         expect(response).to render_template(partial: "_cards")
       end
+
+      context "NewBrowse AB test" do
+        subject { get :show, params: { top_level_slug: "benefits" } }
+
+        %w[A B Z].each do |variant|
+          it "with variant #{variant}" do
+            with_variant NewBrowse: variant do
+              expect(subject).to render_template(:show)
+            end
+          end
+        end
+      end
     end
 
     it "404 if the browse page does not exist" do