Keep all session tests in the same file

railties/test/application/middleware/session_test.rb

@@ -345,5 +345,33 @@ def read_raw_cookie
       get '/foo/read_raw_cookie'
       assert_equal 2, verifier.verify(last_response.body)['foo']
     end
+
+    test 'calling reset_session on request does not trigger an error for API apps' do
+      add_to_config 'config.api_only = true'
+
+      controller :test, <<-RUBY
+        class TestController < ApplicationController
+          def dump_flash
+            request.reset_session
+            render plain: 'It worked!'
+          end
+        end
+      RUBY
+
+      app_file 'config/routes.rb', <<-RUBY
+        Rails.application.routes.draw do
+          get '/dump_flash' => "test#dump_flash"
+        end
+      RUBY
+
+      require "#{app_path}/config/environment"
+
+      get '/dump_flash'
+
+      assert_equal 200, last_response.status
+      assert_equal 'It worked!', last_response.body
+
+      refute Rails.application.middleware.include?(ActionDispatch::Flash)
+    end
   end
 end