Ensure rails_helper is not modified is pre-configured

test/generators/suspenders/factories_generator_test.rb

@@ -175,6 +175,20 @@ class FactoriesGenerator::RSpecTest < Rails::Generators::TestCase
         end
       end
 
+      test "does not modify rails_helper if it's configured to include support files" do
+        touch("spec/rails_helper.rb")
+        rails_helper = <<~RUBY
+          Dir[Rails.root.join("spec/support/**/*.rb")].sort.each { |file| require file }
+        RUBY
+        File.open(app_root("spec/rails_helper.rb"), "w") { _1.write rails_helper }
+
+        run_generator
+
+        assert_file app_root("spec/rails_helper.rb") do |file|
+          assert_equal rails_helper, file
+        end
+      end
+
       test "creates linting test" do
         factories_spec = <<~RUBY
           require "rails_helper"