Rails 5 default_url_options oddities

I have a pretty simple rails app that I'm working on upgrading from Rails 4 to Rails 5, but I'm noticing some weirdness with `default_url_options` In `config/environments/test.rb` I have: ``` Rails.application.routes.default_url_options[:host]= ENV["HTTP_HOST"] || "localhost" Rails.application.routes.default_url_options[:port]= ENV["PORT"] || 3000 ``` My application has a namespace called `api`. In my request specs, I'm seeing this: ``` [1] pry> api_v3_sample_url => "http://www.example.com:3000/api/v3/sample" [2] pry> Rails.application.routes.url_helpers.api_v3_sample_url => "http://localhost:3000/api/v3/sample" ``` What am I missing that is causing those URLs to be different? EDIT Per this thread I set ``` config.action_controller.default_url_options = { host: ENV['HTTP_HOST'] || 'localhost' } ``` in `config/environments/test.rb` but now I get this: ``` > Rails.application.routes.url_helpers.api_v3_sample_url ArgumentError: Missing host to link to! Please provide the :host parameter, set default_url_options[:host], or set :only_path to true > api_v3_sample_url => "http://www.example.com/api/v3/sample" ``` EDIT 2 Probably worth noting that these are request specs and not feature specs (not using capybara).