Assert template snippets don't get layout

test/integration/templates/non_layout_templates_test.rb

@@ -0,0 +1,21 @@
+require_relative "../../integration_test_helper"
+
+class NonLayoutTemplatesTest < ActionDispatch::IntegrationTest
+  def template_file(name)
+    Rails.root.join("app", "views", "root", "#{name}.html.erb")
+  end
+
+  %w(
+    beta_notice
+    campaign
+    proposition_menu
+    related.raw
+    report_a_problem.raw
+  ).each do |template|
+    should "not add a layout to the #{template} snippet" do
+      get "/templates/#{template}.html.erb"
+
+      refute_match '<html', last_response.body
+    end
+  end
+end