Add admin notifications for new Mastodon versions (#26582)

spec/features/admin/software_updates_spec.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe 'finding software updates through the admin interface' do
+  before do
+    Fabricate(:software_update, version: '99.99.99', type: 'major', urgent: true, release_notes: 'https://github.com/mastodon/mastodon/releases/v99')
+
+    sign_in Fabricate(:user, role: UserRole.find_by(name: 'Owner')), scope: :user
+  end
+
+  it 'shows a link to the software updates page, which links to release notes' do
+    visit settings_profile_path
+    click_on I18n.t('admin.critical_update_pending')
+
+    expect(page).to have_title(I18n.t('admin.software_updates.title'))
+
+    expect(page).to have_content('99.99.99')
+
+    click_on I18n.t('admin.software_updates.release_notes')
+    expect(page).to have_current_path('https://github.com/mastodon/mastodon/releases/v99', url: true)
+  end
+end