Mongoid::Errors::DocumentNotFound: 
message:
  Document not found for class UserBilling with attributes {:user_id=>950961012}.
summary:
  When calling UserBilling.find_by with a hash of attributes, all attributes provided must match a document in the database or this error will be raised.
resolution:
  Search for attributes that are in the database or set the Mongoid.raise_not_found_error configuration option to false, which will cause nil to be returned instead of raising this error.
    test/integration/billing_address_test.rb:51:in `block in <class:BillingAddressTest>'