Add cookieless A/A test

This commit adds the cookieless A/A test to government-frontend, which fires on every request. The purpose of the cookieless A/A test is to test an approach with our CDN which does not use cookies for A/B testing, and is something that we intend to use to A/B test the cookie consent banner should the A/A test be successful; as the cookie consent banner is presented up until users either consent to or decline cookies, we need to be able to understand which variant a user falls in before they have consented to cookies. The data involved in this is the variant of the test only - no other data is being sent to analytics, and data that is generally sent by default has been masked by hardcoding the various properties.

This test has been approved by IA on the basis set out above, for collecting only variant data.

In terms of the changes in this commit, there is _some_ duplication with the cookieless-tracker.js file, which has been largely copied from _Static_ but scoped only to send the data that we need to send. This approach has been verified with @DilwoarH.

app/assets/javascripts/modules/cookieless-tracker.js

@@ -0,0 +1,116 @@
+window.GOVUK = window.GOVUK || {}
+window.GOVUK.Modules = window.GOVUK.Modules || {};
+
+(function (Modules) {
+  var CookielessTracker = function (trackingId, fieldsObject) {
+    var trackerName = fieldsObject.name + '.'
+
+    function configureProfile () {
+      // https://developers.google.com/analytics/devguides/collection/analyticsjs/command-queue-reference#create
+      sendToGa('create', trackingId, fieldsObject)
+    }
+
+    function anonymizeIp () {
+      // https://developers.google.com/analytics/devguides/collection/analyticsjs/advanced#anonymizeip
+      sendToGa(trackerName + 'set', 'anonymizeIp', true)
+    }
+
+    function disableAdFeatures () {
+      // https://developers.google.com/analytics/devguides/collection/analyticsjs/field-reference#allowAdFeatures
+      sendToGa(trackerName + 'set', 'allowAdFeatures', false)
+    }
+
+    function stripTitlePII () {
+      sendToGa(trackerName + 'set', 'title', '')
+    }
+
+    function stripLocationPII () {
+      sendToGa(trackerName + 'set', 'location', '')
+    }
+
+    function load () {
+      /* eslint-disable */
+      (function (i, s, o, g, r, a, m) { i['GoogleAnalyticsObject'] = r; i[r] = i[r] || function () {
+        (i[r].q = i[r].q || []).push(arguments) }, i[r].l = 1 * new Date(); a = s.createElement(o),
+        m = s.getElementsByTagName(o)[0]; a.async = 1; a.src = g; m.parentNode.insertBefore(a, m)
+      })(window, document, 'script', 'https://www.google-analytics.com/analytics.js', 'ga')
+      /* eslint-enable */
+    }
+
+    // Support legacy cookieDomain param
+    if (typeof fieldsObject === 'string') {
+      fieldsObject = { cookieDomain: fieldsObject }
+    }
+
+    load()
+    configureProfile()
+    anonymizeIp()
+    disableAdFeatures()
+    stripTitlePII()
+    stripLocationPII()
+  }
+
+  CookielessTracker.load = function () {
+    /* eslint-disable */
+    (function (i, s, o, g, r, a, m) { i['GoogleAnalyticsObject'] = r; i[r] = i[r] || function () {
+      (i[r].q = i[r].q || []).push(arguments) }, i[r].l = 1 * new Date(); a = s.createElement(o),
+      m = s.getElementsByTagName(o)[0]; a.async = 1; a.src = g; m.parentNode.insertBefore(a, m)
+    })(window, document, 'script', 'https://www.google-analytics.com/analytics.js', 'ga')
+    /* eslint-enable */
+  }
+
+  // https://developers.google.com/analytics/devguides/collection/analyticsjs/events
+  CookielessTracker.prototype.trackEvent = function (category, action, options) {
+    options = options || {}
+    var value
+    var trackerName = ''
+    var evt = {
+      hitType: 'event',
+      eventCategory: category,
+      eventAction: action
+    }
+
+    // Label is optional
+    if (typeof options.label === 'string') {
+      evt.eventLabel = options.label
+      delete options.label
+    }
+
+    // Value is optional, but when used must be an
+    // integer, otherwise the event will be invalid
+    // and not logged
+    if (options.value || options.value === 0) {
+      value = parseInt(options.value, 10)
+      if (typeof value === 'number' && !isNaN(value)) {
+        options.eventValue = value
+      }
+      delete options.value
+    }
+
+    // trackerName is optional
+    if (typeof options.trackerName === 'string') {
+      trackerName = options.trackerName + '.'
+      delete options.trackerName
+    }
+
+    // Prevents an event from affecting bounce rate
+    // https://developers.google.com/analytics/devguides/collection/analyticsjs/events#implementation
+    if (options.nonInteraction) {
+      options.nonInteraction = 1
+    }
+
+    if (typeof options === 'object') {
+      $.extend(evt, options)
+    }
+
+    sendToGa(trackerName + 'send', evt)
+  }
+
+  function sendToGa () {
+    if (typeof window.ga === 'function') {
+      window.ga.apply(window, arguments)
+    }
+  }
+
+  Modules.CookielessTracker = CookielessTracker
+})(window.GOVUK.Modules)

app/assets/javascripts/modules/track-variant.js

@@ -0,0 +1,32 @@
+window.GOVUK.Modules = window.GOVUK.Modules || {};
+
+(function (Modules) {
+  'use strict'
+
+  Modules.TrackVariant = function () {
+    this.start = function ($element) {
+      var element = $element[0]
+
+      if (window.GOVUK.cookie('cookies_preferences_set') !== 'true') {
+        var variant = element.getAttribute('content')
+
+        if (variant === undefined) {
+          return
+        }
+
+        var cookielessTracker = new GOVUK.Modules.CookielessTracker('UA-26179049-29', {
+          name: 'CookielessTracker',
+          storage: 'none',
+          clientId: '0'
+        })
+
+        cookielessTracker.trackEvent('cookieless', 'hit', {
+          trackerName: 'CookielessTracker',
+          label: variant,
+          javaEnabled: false,
+          language: ''
+        })
+      }
+    }
+  }
+})(window.GOVUK.Modules)

app/controllers/application_controller.rb

@@ -3,6 +3,8 @@ class ApplicationController < ActionController::Base
   # For APIs, you may want to use :null_session instead.
   protect_from_forgery except: :service_sign_in_options
 
+  include CookielessTestable
+
   if ENV["BASIC_AUTH_USERNAME"]
     http_basic_authenticate_with(
       name: ENV.fetch("BASIC_AUTH_USERNAME"),

app/controllers/concerns/cookieless_testable.rb

@@ -0,0 +1,31 @@
+module CookielessTestable
+  extend ActiveSupport::Concern
+
+  CUSTOM_DIMENSION = 49
+
+  def self.included(base)
+    base.helper_method(
+      :cookieless_variant,
+    )
+    base.after_action :set_test_response_header
+  end
+
+  def cookieless_variant
+    @cookieless_variant ||= cookieless_test.requested_variant(request.headers)
+  end
+
+private
+
+  def cookieless_test
+    @cookieless_test ||= GovukAbTesting::AbTest.new(
+      "CookielessAATest",
+      dimension: CUSTOM_DIMENSION,
+      allowed_variants: %w[A B Z],
+      control_variant: "Z",
+    )
+  end
+
+  def set_test_response_header
+    cookieless_variant.configure_response(response)
+  end
+end

app/views/layouts/application.html.erb

@@ -26,6 +26,11 @@
   <% if @content_item.description %>
     <meta name="description" content="<%= strip_tags(@content_item.description) %>" />
   <% end %>
+  
+  <%= cookieless_variant.analytics_meta_tag.html_safe %>
+  <% unless cookieless_variant.variant?('Z') %>
+    <meta name="Cookieless-Variant" content="<%= cookieless_variant.variant_name %>" data-module="track-variant">
+  <% end %>
 
   <%= yield :extra_head_content %>
 </head>

spec/javascripts/track-variant-spec.js

@@ -0,0 +1,61 @@
+describe('Test variant tracker', function () {
+  'use strict'
+
+  var tracker,
+    element,
+    FakeCookielessTracker,
+    gaSpy
+
+  beforeEach(function () {
+    GOVUK.cookie('cookies_preferences_set', null)
+    gaSpy = jasmine.createSpyObj('initGa', ['send'])
+
+    FakeCookielessTracker = function (trackingId, fieldsObject) {}
+    FakeCookielessTracker.prototype.trackEvent = function (category, action, options) {
+      gaSpy.send(category, action, options)
+    }
+
+    GOVUK.Modules.CookielessTracker = FakeCookielessTracker
+
+    tracker = new GOVUK.Modules.TrackVariant()
+  })
+
+  afterEach(function () {
+    GOVUK.Modules.CookielessTracker = null
+  })
+
+  it('tracks A variant', function () {
+    element = $('<meta name="Cookieless-Variant" content="A" data-module="track-variant">')
+
+    tracker.start(element)
+
+    expect(gaSpy.send).toHaveBeenCalledWith('cookieless', 'hit', {
+      trackerName: 'CookielessTracker',
+      label: 'A',
+      javaEnabled: false,
+      language: ''
+    })
+  })
+
+  it('tracks B variant', function () {
+    element = $('<meta name="Cookieless-Variant" content="B" data-module="track-variant">')
+
+    tracker.start(element)
+
+    expect(gaSpy.send).toHaveBeenCalledWith('cookieless', 'hit', {
+      trackerName: 'CookielessTracker',
+      label: 'B',
+      javaEnabled: false,
+      language: ''
+    })
+  })
+
+  it('does not track variant if cookie is set', function () {
+    GOVUK.cookie('cookies_preferences_set', true)
+    element = $('<meta name="Cookieless-Variant" content="Z" data-module="track-variant">')
+
+    tracker.start(element)
+
+    expect(gaSpy.send).not.toHaveBeenCalled()
+  })
+})

test/controllers/content_items_controller_test.rb

@@ -385,6 +385,26 @@ class ContentItemsControllerTest < ActionController::TestCase
     assert_select ".gem-c-contextual-footer", false
   end
 
+  %w[A B].each do |test_variant|
+    test "record cookieless hit when in variant #{test_variant}" do
+      with_variant CookielessAATest: test_variant.to_s do
+        content_item = content_store_has_schema_example("case_study", "case_study")
+
+        get :show, params: { path: path_for(content_item) }
+        assert_select "meta[data-module=track-variant][content=#{test_variant}]"
+      end
+    end
+  end
+
+  test "not record cookieless hit when in variant Z" do
+    with_variant CookielessAATest: "Z" do
+      content_item = content_store_has_schema_example("case_study", "case_study")
+
+      get :show, params: { path: path_for(content_item) }
+      assert_select "meta[data-module=track-variant]", false
+    end
+  end
+
   def path_for(content_item, locale = nil)
     base_path = content_item["base_path"].sub(/^\//, "")
     base_path.gsub!(/\.#{locale}$/, "") if locale