added switch app menu item

Added test to verify switch app menu item

Updated code to include system test for switch app menu item

updated code in user helper to remove warning messages in test suite

app/views/layouts/application.html.erb

@@ -24,6 +24,10 @@
         href: root_path,
         active: current_page?(root_path),
       },
+      {
+        text: "Switch app",
+        href: Plek.external_url_for("signon"),
+      },
     ],
   } %>
 

spec/rails_helper.rb

@@ -24,4 +24,7 @@
   config.expose_dsl_globally = false
   config.infer_spec_type_from_file_location!
   config.use_transactional_fixtures = true
+  config.before(:each, type: :system) do
+    driven_by :rack_test
+  end
 end

spec/support/users_helper.rb

@@ -11,11 +11,11 @@ def as_other_department_user(&block)
 end
 
 def as_logged_in_user(permissions, organisation_slug, &_block)
-  allow(@controller).to receive(:authenticate_user!).and_return(true)
-  allow(@controller).to receive(:user_signed_in?).and_return(true)
-  allow(@controller).to receive(:current_user).and_return(User.new(permissions:, organisation_slug:))
+  allow_any_instance_of(ApplicationController).to receive(:authenticate_user!).and_return(true)
+  allow_any_instance_of(ApplicationController).to receive(:user_signed_in?).and_return(true)
+  allow_any_instance_of(ApplicationController).to receive(:current_user).and_return(User.new(permissions:, organisation_slug:))
   yield
-  allow(@controller).to receive(:authenticate_user!).and_call_original
-  allow(@controller).to receive(:user_signed_in?).and_call_original
-  allow(@controller).to receive(:current_user).and_call_original
+  allow_any_instance_of(ApplicationController).to receive(:authenticate_user!).and_call_original
+  allow_any_instance_of(ApplicationController).to receive(:user_signed_in?).and_call_original
+  allow_any_instance_of(ApplicationController).to receive(:current_user).and_call_original
 end

spec/system/main_menu_spec.rb

@@ -0,0 +1,16 @@
+require "rails_helper"
+
+RSpec.describe "Main menu" do
+  context "as a normal user" do
+    it "shows the Services/Switch app menu items and goes to signon when Switch app is clicked" do
+      as_gds_editor do
+        visit "/admin"
+
+        within(".govuk-header__container") do
+          expect(page).to have_link("Services")
+          expect(page).to have_link("Switch app")
+        end
+      end
+    end
+  end
+end