Add govuk_web_banners gem

- Add JS used by global banners, and banner dependencies
- Add global/emergency banner support in layouts
- Add initializer for emergency banner REDIS support
- Mock redis client in all tests (we're not explicitly
  testing emergency banner support here, since we assume
  that's tested adequately in the gem).

Gemfile

@@ -10,6 +10,7 @@ gem "gds-api-adapters"
 gem "govuk_app_config"
 gem "govuk_personalisation"
 gem "govuk_publishing_components"
+gem "govuk_web_banners"
 gem "jwt"
 gem "plek"
 gem "ratelimit"

Gemfile.lock

@@ -169,6 +169,11 @@ GEM
       capybara (>= 3.36)
       puma
       selenium-webdriver (>= 4.0)
+    govuk_web_banners (1.0.0)
+      govuk_app_config
+      govuk_publishing_components
+      rails (>= 7)
+      redis
     hashdiff (1.1.2)
     http-accept (1.7.0)
     http-cookie (1.0.8)
@@ -651,6 +656,7 @@ DEPENDENCIES
   govuk_publishing_components
   govuk_schemas
   govuk_test
+  govuk_web_banners
   jwt
   plek
   pry-byebug

app/assets/javascripts/application.js

@@ -3,4 +3,7 @@
 //= require govuk_publishing_components/components/error-summary
 //= require govuk_publishing_components/components/radio
 //= require govuk_publishing_components/components/feedback
+//= require govuk_publishing_components/components/global-banner
 //= require govuk_publishing_components/components/layout-super-navigation-header
+
+//= require govuk_web_banners/dependencies

app/views/layouts/account.html.erb

@@ -24,6 +24,8 @@
 <%= render "govuk_publishing_components/components/layout_for_public", {
   title: yield(:title),
   blue_bar: false,
+  emergency_banner: render("govuk_web_banners/emergency_banner"),
+  global_banner: render("govuk_web_banners/global_banner"),
   omit_feedback_form: true,
   omit_footer_border: true,
   omit_global_banner: true,

app/views/layouts/application.html.erb

@@ -27,6 +27,8 @@
 <%= render "govuk_publishing_components/components/layout_for_public", {
       title: yield(:title),
       show_explore_header: true,
+      emergency_banner: render("govuk_web_banners/emergency_banner"),
+      global_banner: render("govuk_web_banners/global_banner"),
   } do %>
   <%= yield :body %>
   <%= javascript_include_tag 'application', type: "module" %>

config/initializers/govuk_web_banners.rb

@@ -0,0 +1,4 @@
+Rails.application.config.emergency_banner_redis_client = Redis.new(
+  url: ENV["EMERGENCY_BANNER_REDIS_URL"],
+  reconnect_attempts: [0, 0.1, 0.25],
+)

spec/spec_helper.rb

@@ -30,5 +30,6 @@
   config.before :each do
     rate_limiter = instance_double(Ratelimit, add: nil, exceeded?: false)
     allow(Ratelimit).to receive(:new).and_return(rate_limiter)
+    Rails.application.config.emergency_banner_redis_client = instance_double(Redis, hgetall: {})
   end
 end