Use policy to decide when deleted projects tab should be visible

Split the projects_submenu method into two so that it can be
easily extended for EE.

app/helpers/nav/top_nav_helper.rb

@@ -103,7 +103,7 @@ module Nav
           shortcut_href: dashboard_projects_path,
           **projects_menu_item_attrs
         )
-        builder.add_view(PROJECTS_VIEW, container_view_props(namespace: 'projects', current_item: current_item, submenu: projects_submenu(::Gitlab::Nav::TopNavMenuBuilder.new)))
+        builder.add_view(PROJECTS_VIEW, container_view_props(namespace: 'projects', current_item: current_item, submenu: projects_submenu))
       end
 
       if dashboard_nav_link?(:groups)
@@ -252,14 +252,19 @@ module Nav
       }
     end
 
-    def projects_submenu(builder, should_build = true)
+    def projects_submenu
+      builder = ::Gitlab::Nav::TopNavMenuBuilder.new
+      projects_submenu_items(builder: builder)
+      builder.build
+    end
+
+    def projects_submenu_items(builder:)
       # These project links come from `app/views/layouts/nav/projects_dropdown/_show.html.haml`
       builder.add_primary_menu_item(id: 'your', title: _('Your projects'), href: dashboard_projects_path)
       builder.add_primary_menu_item(id: 'starred', title: _('Starred projects'), href: starred_dashboard_projects_path)
       builder.add_primary_menu_item(id: 'explore', title: _('Explore projects'), href: explore_root_path)
       builder.add_primary_menu_item(id: 'topics', title: _('Explore topics'), href: topics_explore_projects_path)
       builder.add_secondary_menu_item(id: 'create', title: _('Create new project'), href: new_project_path)
-      builder.build if should_build
     end
 
     def groups_submenu

ee/app/controllers/ee/dashboard/projects_controller.rb

@@ -41,7 +41,7 @@ module EE
       end
 
       def check_adjourned_deletion_listing_availability
-        return render_404 unless License.feature_available?(:adjourned_deletion_for_projects_and_groups)
+        return render_404 unless can?(current_user, :list_removable_projects)
       end
 
       def finder_params_for_removed

ee/app/helpers/ee/nav/top_nav_helper.rb

@@ -51,15 +51,13 @@ module EE
         end
       end
 
-      override :projects_submenu
-      def projects_submenu(builder, should_build = true)
-        super(builder, false)
+      override :projects_submenu_items
+      def projects_submenu_items(builder:)
+        super
 
         if License.feature_available?(:adjourned_deletion_for_projects_and_groups)
           builder.add_primary_menu_item(id: 'deleted', title: _('Deleted projects'), href: removed_dashboard_projects_path)
         end
-
-        builder.build if should_build
       end
     end
   end

ee/app/policies/ee/global_policy.rb

@@ -13,6 +13,10 @@ module EE
         License.feature_available?(:pages_size_limit)
       end
 
+      condition(:adjourned_project_deletion_available) do
+        License.feature_available?(:adjourned_deletion_for_projects_and_groups)
+      end
+
       condition(:export_user_permissions_available) do
         ::License.feature_available?(:export_user_permissions)
       end
@@ -53,6 +57,10 @@ module EE
         prevent :create_group_with_default_branch_protection
       end
 
+      rule { adjourned_project_deletion_available }.policy do
+        enable :list_removable_projects
+      end
+
       rule { export_user_permissions_available & admin }.enable :export_user_permissions
 
       rule { can?(:create_group) }.enable :create_group_via_api

ee/app/views/dashboard/_removed_projects_tab.html.haml

-- if License.feature_available?(:adjourned_deletion_for_projects_and_groups)
+- if can?(current_user, :list_removable_projects)
   = gl_tab_link_to removed_dashboard_projects_path, { data: { placement: 'right' } } do
     = _("Pending deletion")
     = gl_tab_counter_badge(limited_counter_with_delimiter(removed_projects_count))

ee/app/views/shared/projects/_removed.html.haml

-- if License.feature_available?(:adjourned_deletion_for_projects_and_groups) && scheduled_for_deletion?(project)
+- if can?(current_user, :list_removable_projects) && scheduled_for_deletion?(project)
   .gl-display-flex.gl-align-items-center.gl-flex-wrap.project-title
     %span.small
       = _("Marked For Deletion At - %{deletion_time}") % { deletion_time: project.marked_for_deletion_at.strftime(Date::DATE_FORMATS[:medium]) }

ee/spec/policies/global_policy_spec.rb

@@ -199,6 +199,48 @@ RSpec.describe GlobalPolicy do
     end
   end
 
+  describe 'list_removable_projects' do
+    context 'when user is an admin', :enable_admin_mode do
+      let_it_be(:current_user) { admin }
+
+      before do
+        stub_licensed_features(adjourned_deletion_for_projects_and_groups: licensed?)
+      end
+
+      context 'when licensed feature is enabled' do
+        let(:licensed?) { true }
+
+        it { is_expected.to be_allowed(:list_removable_projects) }
+      end
+
+      context 'when licensed feature is not enabled' do
+        let(:licensed?) { false }
+
+        it { is_expected.to be_disallowed(:list_removable_projects) }
+      end
+    end
+
+    context 'when user is a normal user' do
+      let_it_be(:current_user) { create(:user) }
+
+      before do
+        stub_licensed_features(adjourned_deletion_for_projects_and_groups: licensed?)
+      end
+
+      context 'when licensed feature is enabled' do
+        let(:licensed?) { true }
+
+        it { is_expected.to be_allowed(:list_removable_projects) }
+      end
+
+      context 'when licensed feature is not enabled' do
+        let(:licensed?) { false }
+
+        it { is_expected.to be_disallowed(:list_removable_projects) }
+      end
+    end
+  end
+
   describe ':export_user_permissions', :enable_admin_mode do
     using RSpec::Parameterized::TableSyntax