If you want to have routes that are only available in tests (e.g. for testing obscure redirects), you can use the with_routing helper – but that one destroys existing routes which may break a specs that require them to work.
To keep both "regular" and test routes, do this:
class MyApplicationController < ActionController::Base
render text: 'Welcome to my application'
test_routes = Proc...
Custom matchers are a useful RSpec feature which you can use to DRY up repetitive expectations in your specs. Unfortunately the default directory structure generated by rspec-rails has no obvious place to put custom matchers or other support code.
You can define methods in any example group using Ruby's def keyword or define_method method. These helper methods are exposed to examples in the group in which they are defined and groups nested within that group, but not parent or sibling groups.