Specs for minimal CSP policy in Api:: controllers (#27845)

spec/requests/api/v1/csp_spec.rb

@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe 'API namespace minimal Content-Security-Policy' do
+  before { stub_tests_controller }
+
+  after { Rails.application.reload_routes! }
+
+  it 'returns the correct CSP headers' do
+    get '/api/v1/tests'
+
+    expect(response).to have_http_status(200)
+    expect(response.headers['Content-Security-Policy']).to eq(minimal_csp_headers)
+  end
+
+  private
+
+  def stub_tests_controller
+    stub_const('Api::V1::TestsController', api_tests_controller)
+
+    Rails.application.routes.draw do
+      get '/api/v1/tests', to: 'api/v1/tests#index'
+    end
+  end
+
+  def api_tests_controller
+    Class.new(Api::BaseController) do
+      def index
+        head 200
+      end
+
+      private
+
+      def user_signed_in? = false
+      def current_user = nil
+    end
+  end
+
+  def minimal_csp_headers
+    "default-src 'none'; frame-ancestors 'none'; form-action 'none'"
+  end
+end