add base feature specs

spec/system/api_settings_spec.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe 'API Settings' do
+  let!(:account) { create(:account) }
+  let!(:user) { create(:user, account:) }
+
+  before do
+    sign_in(user)
+    visit settings_api_index_path
+  end
+
+  it 'shows verify signed PDF page' do
+    expect(page).to have_content('API')
+    expect(page).to have_field('X-Auth-Token', with: user.access_token.token)
+  end
+end