How do I resolve "Missing host to link to! Please provide the :host parameter"? (RoR)

I'm following the RoR Tutorial and I'm stuck at Listing 9.15 I getting the following error after running 'bundle exec rspec spec/' : 1) Authentication authorization as wrong user submitting a PATCH request to the Users#update action Failure/Error: specify { expect(response).to redirect_to(root_url) } ArgumentError: Missing host to link to! Please provide the :host parameter, set default_url_option