Does this really test the functionality? Wouldn't [this](http://stackoverflow.com/a/9329795) be more appropriate?

```ruby
let(:url)     { "http://api.domain.com"     }
let(:bad_url) { "http://bad_url.domain.com" }

it "does allow creation of sign ups" do
  {:post => "#{url}/sign_ups"}.should route_to(
   :controller => "sign_ups",
   :action => "create",
  )
end

it "should not route" do
  {:post => "#{bad_url}/sign_ups"}.should_not route_to(
   :controller => "sign_ups",
   :action => "create",
  )
end
```