Setup Appraisal

spec/dummy/config/application.rb

@@ -8,7 +8,7 @@ Bundler.require(*Rails.groups)
 module Dummy
   class Application < Rails::Application
     # Initialize configuration defaults for originally generated Rails version.
-    config.load_defaults 6.0
+    config.load_defaults 6.0 if Rails::VERSION::MAJOR == 6
 
     # Settings in config/environments/* take precedence over those specified here.
     # Application configuration can go into files in config/initializers
@@ -16,4 +16,3 @@ module Dummy
     # the framework and any gems in your application.
   end
 end
-