I've developed additional perspective on this issue - I have DNS settings in my hosts file that are what resolve the visits to localhost, but also preserve the subdomain in the request (this latter point is important because Rails path helpers care which subdomain is being requested) To sum up the scope of the problem as it stands now - I need a way within Heroku/Capybara system tests to both route requests to localhost, but also maintain the subdomain information of the request. I've been able to accomplish one or the other, but haven't found a configuration that provides both yet.

Unless you are the maintainer of lvh.me, you can not be sure it will not disappear or change its RRs for lvh.me. You can use localhost.localdomain instead of localhost, by adding the following lines in your hosts file: 127.0.0.1 localhost localhost.localdomain ::1 localhost localhost.localdomain This is better than using lvh.me because: you may not always have access to a DNS resolver, when developing